Consequences of multilingualism for neural architecture

Sayuri Hayakawa; Viorica Marian

doi:10.1186/s12993-019-0157-z

Consequences of multilingualism for neural architecture

Hayakawa, Sayuri; Marian, Viorica 2019-03-25 00:00:00 Language has the power to shape cognition, behavior, and even the form and function of the brain. Technological and scientific developments have recently yielded an increasingly diverse set of tools with which to study the way language changes neural structures and processes. Here, we review research investigating the consequences of mul- tilingualism as revealed by brain imaging. A key feature of multilingual cognition is that two or more languages can become activated at the same time, requiring mechanisms to control interference. Consequently, extensive experi- ence managing multiple languages can influence cognitive processes as well as their neural correlates. We begin with a brief discussion of how bilinguals activate language, and of the brain regions implicated in resolving language conflict. We then review evidence for the pervasive impact of bilingual experience on the function and structure of neural networks that support linguistic and non-linguistic cognitive control, speech processing and production, and language learning. We conclude that even seemingly distinct effects of language on cognitive operations likely arise from interdependent functions, and that future work directly exploring the interactions between multiple levels of processing could offer a more comprehensive view of how language molds the mind. Keywords: Bilingualism, Multilingualism, Neuroplasticity, Experience-dependent plasticity, Language experience, Cognitive function, Executive control, Language learning, Speech processing cortex after just 7 days of learning to juggle [5]. Here, we Background discuss the neurofunctional and neurostructural con There are nomadic children off the coast of Thailand - who can “see like dolphins” [1]. These sea nomads of the sequences of a different type of juggling—namely, the Moken tribe spend considerable time diving for food, experience of juggling multiple languages within a single and have consequently learned to adjust their pupils to cognitive system. improve their vision underwater [2]. Such differences Language processing ranks among the most ubiqui- among people of different backgrounds and expertise tous, yet cognitively complex tasks that we engage in on a illustrate the powerful influence that experience can have daily basis. But unlike the effort put into activities such as on the function and physiology of our bodies. What may practicing the piano or training for a marathon, the per- be more surprising is that experience can change the vasiveness of language in almost every facet of our lives brain. There is now substantial evidence of neuroplastic makes it easy to overlook as a form of intense exercise. changes associated with expertise, ranging from enlarged This is especially the case for bilinguals, who may appear hippocampi among London taxi drivers [3] to greater to function effortlessly in a single language, while cov - volume in insular subregions of expert action video ertly managing multiple linguistic systems that may be game players [4]. Even brief periods of training have been competing with each other for activation. Early models shown to elicit structural changes, such as in the case of of bilingual cognition posited that one language could be increased gray matter density in the occipito-temporal independently activated without the other, either through a single “language switch” mechanism (i.e., Penfield and Roberts’ “one switch” model [6]), or through independ- *Correspondence: v-marian@northwestern.edu ent switches for output (controlled by the speaker) and Department of Communication Sciences and Disorders, Northwestern input (controlled by the environment) (i.e., Macnamara’s University, 2240 Campus Drive, Evanston, IL 60208, USA © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat iveco mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creat iveco mmons .org/ publi cdoma in/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 2 of 24 “two switch” model [7]). Since then, research has led to the basal ganglia and their constituent regions includ- a more integrated view of bilingual cognition, although ing the putamen and caudate nucleus, which are associ- the strength of activation for each language can indeed ated with functions involved in procedural memory, skill be selectively influenced by both top-down (e.g., expec - learning, planning, and coordination [38, 40–42]. The tations [8, 9]) and bottom-up inputs (e.g., language-spe- repeated engagement of these neural networks to man- cific acoustic cues [10, 11]). In fact, research utilizing age language conflict has both functional and structural numerous techniques ranging from eye-tracking [12– consequences. In some cases, bilingual experience affects 20] to electroencephalography (EEG) [21–26] has pro- neural activity in the absence of behavioral changes, vided ample evidence that multiple languages can be, while in others, it has been associated with a number and often are, activated in parallel. Using eye-tracking of language-specific and domain-general advantages and the visual world paradigm [27, 28], Spivey and Mar- relative to monolinguals. In the following sections, we ian [12] observed that when Russian-English bilinguals review some examples of how bilingual experience can were asked to pick up a particular object from an array, affect both the function and structure of neural regions they made eye movements towards other objects with underlying different components of language processing. phonologically similar labels. Critically, bilinguals fix - Given that managing language conflict is among the most ated on both within- and between-language competi- essential functions for bilingual language processing, tors, such that an instruction to pick up the “marker” we begin with neuroplastic changes to networks associ- in English would elicit eye movements towards a stamp ated with linguistic and non-linguistic cognitive control. (“marka” in Russian). This demonstrates that bilinguals We then provide evidence that bilingual experience can may consider lexical candidates from both languages influence some of the earliest stages of language process - during speech comprehension. Utilizing EEG, Thierry ing by altering how people encode and attend to sounds, and Wu [26] observed that when Chinese-English bilin- resulting in behavioral consequences for speech percep- guals were asked to judge the semantic relatedness of two tion and production. Lastly, we consider how changes to words in English, their brain potentials indicated activa- both high-level executive functions and low-level percep- tion of their Chinese translations. Specifically, there was tion can impact the ability to learn additional languages a reduction in the N400 component (an index of seman- (e.g., L3, L4, …) (see Fig. 1 for a visual schematic of the tic integration) both when participants judged words that processes and neural regions affected by bilingual experi - were related in the target language (English), as well as ence). We broadly organize our discussions around these those that shared a character in the non-target language three topics, not to describe distinct phenomena, but (Chinese). Evidence of co-activation has been observed rather to illustrate the ways in which seemingly disparate across phonological [12], orthographic [29], lexical [21], consequences of bilingual experience may be intertwined and morphosyntactic [30] levels of representation, which through overlapping networks and functions. We there- raises the question of how bilinguals are able to operate fore conclude by stressing the importance of examining in a single-language mode without intrusions from the the relationships among the various effects of bilingual unintended language. experience on the brain in order to fully appreciate the The precise mechanisms that allow for the successful widespread and interconnected consequences of living as control of multiple languages have yet to be definitely a multilingual. established. Some have posited that the non-target lan- guage is inhibited, others that the target language is facil- Linguistic and non‑linguistic cognitive control itated, yet others that the target language is selected (see Functional brain activity [31] for a review). Models such as Green and Abutalebi’s A key feature of bilingual cognition is the parallel acti- Adaptive Control Hypothesis [32] posit a more complex vation of multiple languages, and the subsequent need system that includes various functions such as monitor- to prevent interference from the non-target language. ing, inhibition, task engagement and disengagement, Because language interference appears to be managed which are employed to varying degrees depending on using similar neural networks recruited for general cog- the context. It has also been suggested that bilingual nitive control, there may be a bilingual advantage for language control may recruit many of the same neural tasks that require ignoring irrelevant information (see regions utilized for domain-general cognitive control [43] for review). Such behavioral differences are most [33, 34]. These include the prefrontal cortex, which is readily observed in children and older adults, while the associated with goal maintenance and conflict resolution bilingual advantage appears to be less robust for young [34–36], the anterior cingulate cortex and neighboring adults who generally have a higher capacity for cogni- pre-supplementary motor area, associated with con- tive control [44]. Yet, even when no behavioral differ - flict-monitoring and attention regulation [37–39], and ences are observed, there is evidence that bilinguals may Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 3 of 24 Fig. 1 Multilingual experience has widespread consequences for functions ranging from cognitive control to speech processing to language learning. Practice juggling multiple languages leads to functional and structural changes to the brain, such as to the prefrontal cortex (PFC), anterior cingulate cortex (ACC), caudate nucleus (CN), cerebellum, brainstem, Heschel’s gyrus (HG), putamen, superior temporal gyrus (STG), inferior frontal gyrus (IFG), anterior temporal lobe (ATL), and supramarginal gyrus (SMG) in the inferior parietal cortex (IPC) be utilizing more efficient control processes. Marian greater activation in any regions when resolving within- et al. [45] investigated the neural correlates of linguistic language competition relative to the control condition. control during lexical competition using fMRI and the The frequent practice managing competition not only visual world paradigm described earlier. When monolin- within, but also between languages may make bilinguals guals were asked to select a target among a display that more efficient at resolving linguistic conflicts, leading included a phonologically similar competitor, there was to less reliance on networks associated with cognitive significant activation of executive control regions such control. as the anterior cingulate cortex (ACC) and the superior Evidence of more efficient processing has been found temporal gyrus (STG) relative to trials without a com- during non-linguistic tasks as well. Both Abutalebi petitor. Critically, bilinguals did not have significantly et al. [46] and Garbin et al. [47] observed that bilinguals Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 4 of 24 not only outperformed monolinguals during a non-lin- Potentially in line with the latter hypothesis, Kousaie guistic executive control task, but also had less activity and Phillips observed group differences even for trials in the ACC, consistent with Marian et al.’s [45] find - without conflicting stimuli (i.e., congruent trials), indi - ings. Bilingual experience can additionally influence the cating that bilingualism may confer a global processing functional connectivity between different brain areas. advantage (often referred to as the bilingual executive Becker et al. [48] collected fMRI data from bilinguals processing advantage, or BEPA [60]). Coderre and van and monolinguals as they completed a task requiring Heuven [61] similarly observed that bilinguals had both the application of continuously changing rules. Using faster reaction times and reduced conflict-related ERP Dynamic Causal Modeling, the authors constructed amplitudes compared to monolinguals during non- three models depicting the connectivity of three areas linguistic, non-conflict trials of a modified Stroop task. known to be associated with cognitive flexibility (ACC, Group differences in ERP amplitude were even observed striatum, and dorsolateral prefrontal cortex, or DLPFC) before the potentially conflicting target stimulus was and compared them to the obtained neural data. They presented, suggesting that bilinguals may be engaging in observed that for both bilinguals and monolinguals, the more proactive management of incoming information in ACC was the driving force, influencing activity in the the absence of a conflict. However, there is also evidence striatum and DLPFC to accomplish tasks involving cog- indicative of greater neural efficiency more specific to nitive flexibility. However, while increased ACC activity active inhibitory control (often described as the bilingual resulted in a modest increase in DLPFC and striatum inhibitory control advantage, or BICA [60]). Heidlmayr activity for bilinguals, greater ACC activity prompted et al. [62] found that bilinguals using their L2 showed a significant decreases in activity in both regions for smaller N400 conflict effect during a Stroop task (i.e., the monolinguals. The relatively mild influence of the ACC difference between incongruent and congruent trials) on other regions for bilinguals may be interpreted as compared to monolinguals. Using a flanker task, Dong a reduced response to conflict, potentially consistent and Zhong [49] observed ERP activity consistent with with Abutalebi et al.’s [46] finding. In one case, ACC both BEPA and BICA. Relative to bilingual interpret- activity is directly modulated, while in the other, the ers with less interpreting experience, those with greater influence of ACC on other neural structures is reduced. experience showed a global processing advantage for Studies utilizing EEG have yielded additional evidence conflict monitoring, as indexed by the earlier N2 com - that may be indicative of greater neural efficiency among ponent (i.e., both congruent and incongruent trials), and bilinguals [49–52], though with somewhat variable find - more efficient inhibitory control for the later P3 compo - ings depending on the population and task. One com- nent (i.e., a smaller conflict effect). monly examined ERP measure is the N2 component, Differences in neural efficiency are primarily attributed which is thought to index conflict monitoring [53] or to experience managing linguistic interference, as men- inhibition [54]. The N2 is typically larger when there is a tioned earlier. However, the need to resolve lexical com- conflict (e.g., incongruent trials of a Simon task) [55], and petition is not exclusive to bilinguals, as selecting words is correlated with ACC activity [56]. A number of studies within a language also requires the inhibition of semanti- have revealed larger N2 amplitudes for bilinguals on con- cally and phonologically similar competitors. So why is it flict trials during Go/No-Go [57, 58] and AX-CPT tasks that practice resolving lexical conflicts appears to have a [52], leading some researchers to conjecture that bilin- more significant impact on domain-general processes for guals may be engaging in greater conflict monitoring or bilinguals than monolinguals? Part of the reason is likely inhibition. On the other hand, Kousaie and Phillips [51, due to the fact that bilinguals experience competition 59] observed that bilinguals elicited smaller [51] and ear- both within and across languages. However, another rea- lier [59] N2s during a Stroop task compared to monolin- son may be because bilinguals utilize more overlapping guals. While the smaller N2 amplitude among bilinguals networks for language processing and domain-general differs from the aforementioned findings, it is consistent cognitive control relative to monolinguals [47, 63–65]. In with the results from fMRI studies observing less bilin- one study by Coderre et al. [64], neural activity was meas- gual activation of the ACC, which may reflect a reduced ured while participants completed semantic tasks involv- need for active conflict monitoring (despite equivalent ing non-linguistic competition, linguistic competition, or [51] or even superior [59] performance). It may therefore language processing without competition. The authors be the case that depending on the task and population, observed that while bilinguals recruited similar neural bilinguals either engage in greater inhibition/monitoring regions for all three tasks (e.g., the left inferior frontal (resulting in larger N2s), or else more efficient general gyrus; L IFG), monolinguals utilized different regions processing, thereby reducing the need for active moni- depending on the task. As such, not only do bilinguals toring (resulting in smaller N2s). have more practice managing linguistic conflict relative Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 5 of 24 to monolinguals, but the impact of such practice on gen- experience can result in greater and more flexible coordi - eral cognitive control is likely greater as well. nation of different neural regions and networks. While the exact nature of the mechanisms underlying Next, we review evidence that the effects of bilingual greater efficiency are still under investigation, some mod - experience extend beyond functional changes in neuro- els such as the bilingual anterior to posterior and sub- logical activity to the actual structures that support them. cortical shift (BAPSS) model [66] posit that, over time, bilinguals may begin to recruit different regions to man - Structural brain matter age competition. Specifically, while bilinguals may rely Bilingual experience has been found to increase gray on the typical frontotemporal executive control regions matter density in regions implicated in executive control, during earlier stages, they may begin to recruit more including the DLPFC [75], left caudate nucleus (LCN; [40, automatic posterior perceptual/motor areas as they gain 76, 77]) and the ACC [78]. As noted previously, the pre- greater expertise. Data consistent with this hypothesis frontal cortex, and the DLPFC in particular, is believed to include the aforementioned findings that bilinguals rely play an important role for domain-general cognitive con- less on the ACC compared to monolinguals, as well as trol [79], as well as language control [35, 80]. Increased studies observing greater recruitment of perceptual and gray matter density in regions associated with cognitive motor regions such as the basal ganglia with bilingual control may partly account for the finding that bilingual - experience [67–69]. Luk et al. [70] provide converging ism can delay the onset of dementia [81, 82]. Consist- evidence by looking at resting-state functional connec- ent with this notion, Abutalebi et al. [78] observed that tivity (assessed by examining the correlations in brain while both monolinguals and bilinguals experienced age- activity between a chosen brain area, the IFG in this case, related gray matter reductions in the DLPFC, reduced and all other regions). The bilateral IFG were chosen as gray matter was only correlated with executive control the “seeds,” or sources of comparison, because bilinguals for monolinguals. In other words, while the groups had in their study had greater white matter integrity in these similar age-related effects at the anatomical level, there regions and because the IFG are known to be associated were greater negative consequences for monolinguals’ with both language and cognitive control [64]. While behavioral performance as a result of reduced gray mat- monolinguals had stronger associations between the ter. Though no structural differences of the DLPFC were seeds and other frontal regions, bilinguals had stronger found between the older bilinguals and monolinguals associations between the seeds and occipitoparietal in Abutalebi et al.’s study, Olulade et al. [75] did observe regions, supporting the idea that bilingualism may pro- greater gray matter volume among younger, Spanish– mote the use of more distributed networks involving English bilinguals compared to monolinguals. However, both frontal and perceptual/motor regions. no such increase was observed for English-ASL bimodal In addition to recruiting different networks, bilinguals bilinguals. The authors propose that because bimodal may have generally greater functional connectivity within bilinguals are able to utilize their two languages simulta- and across networks relevant to executive control. Grady neously, language conflict, and subsequent recruitment et al. [71] found that resting-state functional connec- of the DLPFC, is reduced. Interestingly, bimodal bilin- tivity was enhanced for bilinguals in the Default Mode gualism has been associated with increased gray matter Network (DMN; which includes the posterior cingulate, in the LCN, another region associated with language con- ventromedial prefrontal cortex, angular gyri and para- trol [40]. The authors observed that, among bilinguals, hippocampal gyri), and the frontoparietal control net- there was a positive correlation between gray matter den- work (FPC). Activity in the DMN is strongest during rest sity and LCN activation associated with language switch- and reduced during externally driven tasks [72]. Greater ing, providing further support for the involvement of the functional connectivity within the DMN has been shown LCN in bilingual language control. Greater gray mat- to promote deactivation during tasks, which in turn facil- ter density for bilinguals compared to monolinguals has itates performance [73]. Better executive control is thus additionally been found in the ACC [78], which is asso- predicted by the negative correlation between the DMN ciated with conflict monitoring [83, 84]. Abutalebi et al. and the FPC, the latter of which has highly flexible func - [46] observed a positive correlation between gray matter tional connectivity patterns and facilitates task-specific in the ACC and both behavioral and functional indices recruitment of neural regions [74]. In addition to greater of general cognitive control for bilinguals. Interestingly, functional connectivity within networks, Grady et al. no such relationship between gray matter density and observed that functional connectivity was more cor- functional activation/behavior was observed for mono- related across networks for bilinguals relative to mono- linguals. This latter result once again suggests that bilin - linguals. In other words, there is evidence that bilingual gualism can influence both the physical characteristics of Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 6 of 24 neuroanatomical structures, as well as the ways they are indirect measure of white matter integrity, in the cor- utilized. pus callosum (CC; see also [90, 91]), extending to bilat- Potentially related to the issue of processing efficiency, eral superior longitudinal fasciculi (SLF; see also [91]), a number of experiments have found a negative rela- and the right inferior fronto-occipital fasciculus (IFOF; tionship between gray matter in the LCN and language see also [91–93]). The CC is a thick tract connecting the exposure/expertise. DeLuca et al. [85] observed that LCN left and right hemispheres, and is associated with high- gray matter density of sequential bilinguals was reduced level cognitive processes such as executive function [94, after 3 years of immersion in an L2 context, and Pliatsi- 95]). The SLF is a long-range tract connecting the frontal kas et al. [86] observed differences in the LCN of mono - lobe to posterior parietal and temporal cortices, which linguals and bilinguals with less, but not more immersive along with the arcuate fasciculus (AF) is often classi- experience. Similarly, Elmer et al. [87] found that highly fied as the dorsal stream of the language network (espe - trained simultaneous interpreters had less gray matter cially implicated in speech perception and production volume in several language control regions compared to [96]). The IFOF connects frontal, occipital, and parietal multilingual non-interpreters, and that gray matter in the cortices, and has been proposed as the ventral stream of bilateral caudate nucleus was negatively correlated with language processing (associated with semantic process- the number of interpreting hours. At first glance, these ing [97]). Bilinguals with greater white matter integrity results seem at odds with the general observation that have also demonstrated greater functional connectivity gray matter increases with greater language competence between frontal and posterior cortical regions [70]. In (e.g., Hervais-Adelman et al. [76] who observed a positive other words, bilingual experience can facilitate more dis- relationship between gray matter in the caudate nucleus tributed functional connectivity, likely supported by the and a composite index of multilingual experience). How- integrity of white matter structures connecting the fron- ever, as speculated by Elmer et al. [87], reductions in tal lobe with more distant brain areas. gray matter may reflect cortical pruning associated with While a number of studies have reported greater white greater specialization and efficiency. In other words, gray matter integrity for bilinguals compared to monolinguals, matter density in particular regions (such as the LCN) particularly in the IFOF [91–93], there is also evidence of may initially increase as bilinguals gain greater mastery the opposite pattern [98–100]. For instance, Gold et al. over their languages, but then decrease as they become [99] observed that compared to age-matched monolin- more efficient at carrying out necessary functions (such guals, older bilinguals had less white matter integrity in as reducing interference from unwanted languages). This a number of tracts, including the IFOF, CC, and fornix greater efficiency could result from a number of differ - (which originates in the hippocampus and is associ- ent mechanisms, including increased specialization of ated with memory function [101]). Despite the apparent a particular region (such as the ACC as suggested by inconsistency with Luk et al’s findings [70], the authors Abutalebi et al. [46]) or else reliance on regions associ- point out that the bilinguals’ cognitive functioning did ated with different, potentially more procedural, func - not differ from monolinguals despite lower white mat - tions (consistent with the previously discussed BAPSS ter integrity. In fact, behavioral and fMRI data from the model [66]). For instance, DeLuca et al. [85] observed same subjects showed that the bilinguals were faster at that the same population of bilinguals who experienced task-switching despite less activation in frontal execu- a reduction in the LCN had significantly increased gray tive control regions [99]. The authors thus propose that matter volume in the cerebellum. Increased gray matter bilinguals may be efficiently compensating for reduced in the cerebellum has been associated with the ability to integrity in some tracts through the use of different path - control interference from a non-target language [88], as ways and neural regions (such as the relatively intact SLF well as grammatical processing in bilinguals [89]. DeLuca connecting frontal and subcortical areas in the executive et al. propose that their pattern of results may reflect a network). shift in neural networks as a result of more automated L2 Practice learning and managing multiple linguistic sys- processing. tems thus influences how individuals resolve conflict, in As noted previously, neuroimaging and electrophysio- some cases, leading to what appears to be more efficient logical evidence suggest that bilinguals may rely on more cognitive control. Table 1 provides a summary of stud- distributed networks compared to monolinguals [47, ies of language effects for tasks and regions relevant to 65]—a conclusion further supported by studies examin- linguistic and non-linguistic cognitive control. As can ing the integrity of white matter tracts connecting differ - be seen, bilinguals often have less activation of cortical ent areas of the brain. When comparing older bilingual regions traditionally associated with cognitive control and monolingual adults, Luk et al. [70] found that bilin- (such as the ACC and the PFC) when managing conflict. guals had higher fractional anisotropy (FA) values, an On the other hand, in addition to greater gray matter Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 7 of 24 Table 1 Consequences of bilingualism for linguistic and non‑linguistic cognitive control Type Region Effect Task Study ACC Functional ACC Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch for mono only) ACC Mono ≠ bi (greater activa- Visual world (phonological Marian et al. [45] tion for competitor than competition) control, mono only) ACC Mono > bi (activation Flanker Abutalebi et al. [46] associated with conflict effect) ACC Mono > bi (activation Stroop Waldie et al. [69] associated with conflict effect) Structural ACC Mono ≠ bi (− correlation: Flanker Abutalebi et al. [46] gray matter/conflict effect, bi only) ACC Bi > mono (gray matter) Flanker Abutalebi et al. [78, 179] ACC Multilingual con- Elmer et al. [87] trols > interpreters (gray matter); controls ≠ inter- preters (− correlation: gray matter/interpreting hours; interpreters only) Frontal cortex/gyrus Functional L IFG Mono ≠ bi (overlapping Linguistic/non-linguistic Coderre et al. [64] activation across tasks, flanker; semantic cat - bi only) egorization L IFG Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non-switch, bi only) R IFG Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch, mono only) SFG Mono ≠ bi (greater activa- Visual world (phonological Marian et al. [45] tion for competitor than competition) control, mono only) SFG, MFG, IFG Mono > bi (activation Stroop Waldie et al. [69] associated with conflict effect) R SFG/R MFG Between > within- Visual world (phonological Marian et al. [67] language (activation competition) associated with conflict effect) R SFG/R MFG/R IFG Dominant > non-dominant Visual world (phonological Marian et al. [67] language competition competition) (activation associated with conflict effect) Structural DLPFC Mono ≠ bi (− correlation: Flanker Abutalebi et al. [78, 179] gray matter/conflict effect, mono only) SFG Bi > mono (gray matter) Language switching Zou et al. [40] MFG, IFG, R SFG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) IFG Multilingual con- Elmer et al. [87] trols > interpreters (gray matter); controls ≠ inter- preters (− correlation: gray matter/interpreting hours; interpreters only) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 8 of 24 Table 1 (continued) Type Region Effect Task Study Temporal cortex/gyrus Functional MTG, STS Visual world (phonological Marian et al. [45] Mono ≠ bi (greater activa- competition) tion for competitor than control, mono only) Structural R MTG, R ITG, Mono > bi (gray matter) Olulade et al. [75] (experi- ment 1) R STG, L MTG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) L ITG Bi > mono (gray matter) Language switching Zou et al. [40] Parietal cortex/gyrus Functional L IPL Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch for mono only) Structural R IPL Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) L SMG Multilingual con- Elmer et al. [87] trols > interpreters (gray matter) Occipital cortex/gyrus Functional Bi > mono (EEG complex- Non-verbal task switching Grundy et al. [66, 68] ity); mono ≠ bi (− cor- relation: complexity/ conflict effect, bi only) Structural L SOG, L IOG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) Subcortical Functional L CN Bi > mono (activation Stroop Waldie et al. [69] associated with conflict effect) L CN Bi only: more LCN activa- Language switching Zou et al. [40] tion when language switching than when not L CN/L putamen Bi only : between > within- Visual world (phonological Marian et al. [67] language (activation competition) associated with conflict effect) Structural L CN Bi > mono (gray matter) Language switching Zou et al. [40] L CN More > less multilingual Hervais-Adelman et al. [76] experience (gray matter) Striatum Non-verbal task switching Garbin et al. [47] Mono ≠ bi (+ correla- tion: gray matter/faster switching, bi only) CN Controls ≠ interpreters Elmer et al. [87] (− correlation: gray mat- ter/interpreting hours; interpreters only) L CN/Hip/Amg Less > more immersion Deluca et al. [85] (gray matter contraction) L Cb More > less immersion Deluca et al. [85] (gray matter) Cb Mono > bi (gray matter) Olulade et al. [75] (experi- ment 1) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 9 of 24 Table 1 (continued) Type Region Effect Task Study Multiple/other Functional ACC, PFC, striatum Rapid instructed task Becker et al. [48] Bi ≠ mono (− correlation: learning ACC/PFC and striatum for monos; + correlation: ACC/PFC and striatum for bis) e.g., ACC, PFC, CN, puta- Bi > mono (overlapping Verbal/non-verbal switch- Anderson et al. [63] men activation across tasks) ing Bi > mono (overlapping Verbal/non-verbal task Timmer et al. [65] activation across tasks) switching Bi < mono (amplitude of Stroop, Simon, and Eriksen Kousaie and Phillips [51] N2 in Stroop), mono > bi tasks (amplitude of P3 in Simon), bi ≠ mono (longer delay in P3 latency in Eriksen in monos) Bi < mono (N positivity Stroop Coderre and van Heuven Inc post-target onset) [61] Bi > mono (N negativity Inc pre-target onset) Bi < mono (N400 conflict Stroop/negative priming Heidlmayr et al. [62] effect for Stroop) Bi > mono (CRN and ERN LANT Kałamała et al. [50] negativity) More > less interpreting Flanker Dong and Zhong [49] experience (N1/N2 amplitude); less > more interpreting experience (P3 amplitude for incon- gruent trials only) Bi > mono (N2 on NoGo) Go/NoGo Fernandez et al. [57] Bi > mono (N2 and late Go/NoGo Moreno et al. [58] positivity wave on NoGo) Bi > mono (N2 and P3 to AX-CPT Morales et al. [52] AY ) DMN, FPC Bi > mono (resting-state Grady et al. [71] connectivity within and between networks) Frontal, occipital, parietal Bi > mono (frontal-occip- Luk et al. [70] regions itopartietal resting-state connectivity) Bi < mono (frontal resting- state connectivity) Structural SLF, IFOF Bi > mono (white matter) Luk et al. [70] ILF/IFOF, fornix, CC Mono > bi (white matter) Gold et al. [99] volume in these same frontal regions, bilinguals often Summary of functional and structural effects of bilin - have stronger activation of control-relevant subcortical gual experience for tasks and neural regions associated areas (e.g., LCN), which is likely facilitated by more wide- with linguistic and non-linguistic cognitive control. spread and flexible functional and structural connectiv - Given the pervasive involvement of cognitive control in ity. These patterns reflect two possible ways in which a wide variety of tasks (e.g., [102–104]), an effect of bilin - bilingual experience may support executive function—by gualism on this central function could initiate a chain of enhancing the robustness of the underlying neural struc- consequences across multiple domains and stages of pro- tures, as well as by potentially recruiting more efficient cessing. We illustrate the potentially vast impact of bilin- networks to accomplish the same cognitive control task. gual effects on the brain by considering one of the earliest Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 10 of 24 stages of language processing: the perception and pro- than a dozen languages [115]. Moreover, despite the fact duction of speech sounds. that monolingual speakers of tone languages such as Cantonese and Mandarin have been shown to have highly Speech perception and production robust brainstem responses [117, 120], bilingual speak- Functional brain activity ers of two tone languages exhibit even stronger encoding Studies utilizing EEG have provided evidence that bilin- [114]. This additive effect of language experience aligns gual experience can enhance attention to speech stimuli with the finding that the consistency and strength of f0 [105–107]. For instance, both bilingual toddlers and encoding among children is positively associated with the bilingual adults are quicker than monolinguals at detect- amount of bilingual experience [112]. ing language switches [105, 106]. Further evidence comes A recent study by Zhao and Kuhl [121] confirmed the from a study in which children were presented with pic- link between brainstem encoding and conscious speech tures followed by words that were either related or unre- perception. Building on the well-established finding that lated. While ERPs did not vary between language groups the perception of speech sounds varies as a function of at later stages of semantic processing, only bilinguals had native language background (e.g., sensitivity to phone- ERPs indicating attention to unexpected phonemes dur- mic contrasts of the native language [122]), the authors ing early stages [107]. In addition to earlier responses to observed that differences in how sounds were perceived speech stimuli, Chinese–English bilinguals have been correlated with different patterns of encoding at the found to attend more globally to entire words as com- brainstem. It is possible that more robust and consistent pared to English monolinguals who focus the most on encoding among bilinguals could additionally facilitate word onsets, as indexed by the relative amplitude of the discrimination of non-native contrasts, as has been found N1 component, which is associated with attention [108]. for individuals with musical expertise [123]. Early in The authors suggest that because the segments of words development, infants are sensitive to phonetic contrasts that are most critical for word identification may vary of all languages, but eventually become tuned to their across different languages, it may be more efficient to dis - native language. However, it has been suggested that tribute attention across all segments rather than switch bilingual experience may prolong the period of universal strategies depending on which language is being used. discriminability (i.e., “the perceptual wedge hypothesis”). In other words, bilingual experience leads to changes in Petitto et al. [124] found that while 10 to 12-month-old both the time course and distribution of attentional allo- monolingual infants were no longer sensitive to non- cation, and has been found to enhance attentional con- native contrasts, activity in the LIFC indicated that bilin- trol when processing non-speech stimuli as well (e.g., gual infants were sensitive to phonetic contrasts of both tones [109]). native and non-native languages. Findings from a recent Enhanced attentional control among bilinguals has MEG study additionally suggest that 10 to 12-month- even been associated with changes to how robustly old bilinguals may analyze speech sounds based on speech sounds are encoded at the level of the brainstem acoustic (as opposed to phonetic) properties to a greater [110–115]. Auditory brainstem responses (ABR) are a extent than monolinguals [125]. This prolonged period measure of encoding strength, and encoding of the fun- of acoustic analysis may be adaptive for dealing with the damental frequency (f0) in particular has been found to increased variability associated with multiple phonemic be both experience-dependent [116, 117] and predictive systems and may help bilinguals retain the ability to dis- of speech perception ability [118, 119]. Krizman et al. criminate non-native contrasts. Indeed, bilingual infants [111] observed that encoding of the f0 was more robust as old as 18–20 months were found to be sensitive to the for bilinguals than monolinguals when listening to speech phonemic contrasts of a novel language (Ndebele clicks), stimuli such as/da/, and that this enhancement was corre- while monolinguals were not [126]. lated with attentional control. This finding highlights the While enhanced bilingual discrimination of non-native potential interconnectivity of bilingual effects on execu - contrasts does not appear to persist into adulthood at tive function and speech-sound processing. Furthermore, initial exposure [127, 128], there is evidence suggesting the relationship between the consistency of ABRs and that bilinguals may be better at learning non-native con- attentional control has been found to be stronger among trasts relative to monolinguals after training [127, 129, bilinguals compared to monolinguals, likely as a result of 130]. In addition to better discrimination of non-native the greater demands associated with communicating in contrasts during comprehension, bilingualism may con- multiple languages [110]. Recent work has revealed that fer advantages for the production of novel sounds. For the effect of bilingualism on neural encoding is remark - example, Spinu et al. [131] recently found that after train- ably consistent, with similar effects regardless of socio - ing, bilinguals were better able to reproduce a non-native economic status [113], and for bilingual speakers of more Sussex English accent (as measured by the glottal-stop Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 11 of 24 rate) compared to monolinguals. The authors conjecture foreign accents were associated with a reduction in the that this bilingual advantage for phonological acquisition surface area of the STG and MFG [142], though balanced may be related to their more robust encoding of speech bilingual children had relatively less cortical thickness in sounds at the level of the brainstem. Specifically, they these regions. Rodriguez et al. [143] similarly found that propose that stronger subcortical encoding of sounds cortical thickness of the anterior insula was negatively may translate to richer acoustic signals in auditory sen- correlated with the ability to learn foreign phonological sory memory, eventually leading to more efficient pro - contrasts among bilinguals. These latter results may orig - cessing of speech. inate from similar processes as the previously-discussed As with executive control, speech perception and reduction in gray matter volume for expert interpreters production are influenced not only by the efficiency [87]. Specifically, it may be the case that initial training of particular neural regions, but also by the functional enhances cortical volume/thickness while greater exper- connectivity across brain areas. For instance, Ventura- tise and efficiency will eventually lead to cortical pruning. Campos et al. [132] discovered that resting-state func- Consistent with this notion, Elmer et al. [144] found that tional connectivity between inferior frontal (left frontal interpreters had significantly reduced white matter rela - operculum/anterior insula) and parietal regions (left tive to controls in regions associated with sensory-motor superior parietal lobule) predicted how well individu- coupling and speech articulation (e.g., L anterior insula, als were able to learn non-native contrasts after train- R IPL, and upper cortico-spinal tract), as well as with ing. As noted previously, bilingualism has been shown to executive function (e.g., R CN, CC). enhance resting-state functional connectivity in the fron- One region that has been found to be larger for bal- tal–parietal network [71]. Additionally, it has been found anced bilingual children is the putamen [142], consist- that early bilinguals have greater functional connectivity ent with a number of other studies finding greater gray in language networks relevant to phonological process- matter density in this region for bilinguals compared to ing (as well as semantic processing) relative to late bilin- monolinguals [41, 86, 145]. The putamen has been impli - guals with comparable proficiency [133]. Berken et al. cated in language production and articulation [146, 147], [134] similarly observed that early bilinguals had greater dramatically evinced by the fact that lesions to the area connectivity between the IFG and a number of language can disrupt a speaker’s ability to produce phonemes of processing and executive control regions including the their native language, resulting in speech that appears cerebellum, which is associated with processes underly- to be foreign accented (i.e., Foreign-Accent Syndrome ing speech perception and production [135], as well as [148]). Greater gray matter density in the putamen of language control [88]. bilinguals compared to monolinguals is likely to result from the more complex articulatory repertoire associated Structural brain matter with learning and utilizing multiple languages. Among Bilingual experience has been associated with struc- bilinguals, lower proficiency has been associated with tural changes to brain regions supporting both auditory greater putamen activity, possibly reflecting increased processing and speech production. Ressel et al. [136] articulatory effort [41, 146, 149]. Additionally, Berken observed a relationship between early bilingual experi- et al. [150] observed that among sequential bilinguals, ence and increased gray and white matter volumes in there was a positive correlation between more native-like Heschel’s gyrus (HG), a part of the temporal lobe that accents and gray matter density in the left putamen (as contains the primary auditory cortex. Faster [137] and well as a number of other regions implicated in speech- more successful [138] identification of foreign speech motor control). Together, these findings may suggest that sounds has been linked to greater white and gray matter gray matter density in the left putamen underlies native- volumes, respectively. Enhanced volume in this region like articulation ability, and that speakers experiencing among bilinguals thus coincides with the aforemen- difficulty may compensate by activating this region to a tioned advantages for learning non-native phonemic con- greater degree (potentially inducing structural changes as trasts [127, 129, 130]. Mårtensson et al. [139] observed they improve). that compared to controls, bilingual interpreters had Lastly, and as noted previously in our discussion of increased cortical thickness in the superior temporal cognitive control, bilingual experience has been shown gyrus (STG), a region consistently activated during acous- to enhance white matter integrity in the SLF [70, 77, 91], tic–phonetic processing [140]. The authors additionally as well as the IFOF [91–93], representing the dorsal and found greater cortical thickness among interpreters in ventral streams of language processing, respectively. The the middle frontal gyrus (MFG), part of the articulatory SLF, and the AF in particular, are associated with phono- network that contributes to pronunciation aptitude [141]. logical processing and articulation [151]. Among bilin- A recent study with bilingual children found that stronger guals, a number of variables have been shown to affect Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 12 of 24 white matter integrity in the SLF/AF. Higher proficiency at native language competitors relative to bilinguals. [152] and greater immersive L2 experience [100, 153] are In addition to vocabulary acquisition, there is evidence predictive of enhanced structural integrity, while find - that bilingualism may facilitate learning of novel syntax ings for age of L2 acquisition are mixed [152, 154]. While [162, 163], though the findings are somewhat mixed. In Nichols and Joannis [152] found a positive association a recent EEG study, Grey et al. [164] observed no behav- between age of acquisition and white matter in the AF, ioral difference between bilinguals and monolinguals Hämäläinen et al. [154] observed greater white matter for learning an artificial language. However, there were dis - early compared to late bilinguals. tinct ERP patterns associated with their grammatical- Table 2 summarizes recent research on the functional ity judgments. At high proficiency, both monolinguals and structural effects of multilingual experience on oper - and bilinguals showed native-like ERPs (a P600 compo- ations and brain regions relevant to speech perception nent associated with syntactic processing), whereas at and production. There is reliable evidence that bilingual low proficiency, only bilinguals showed this pattern. In experience can enhance attention to speech stimuli and other words, even when no behavioral differences are result in more consistent and robust encoding of sound observed, bilinguals show more native-like processing at in the brainstem, suggesting that bilingual experience has early stages of acquiring a novel language. The authors (often beneficial) effects on the neural functions under - suggest that enhanced cognitive control could once again lying both cognitive control and speech processing. Fur- play a role, as bilinguals may be better able to reduce thermore, the consequences of bilingual experience on interference from the syntax of known languages. As speech processing may partly originate from changes to noted previously, this greater efficiency may be achieved cognitive control. Bilingualism has also been found to through the recruitment of different neural networks to affect the structure of regions underlying both functions, control interference from a non-target language. Evi- though in some cases, it is not yet clear how specific ana - dence of such a process during language learning comes tomical characteristics align with behavioral expertise from Bradley, King, and Hernandez [165] who found and outcomes. In the final section, we extend the poten - that after just 2 h of exposure to a new language, bilin- tial “chain of bilingual consequences” one step further by guals were not only faster at making semantic judgments exploring how enhanced cognitive control and speech in response to novel words compared to monolinguals, processing may translate to a greater capacity for learn- but also recruited different neural networks. Specifically, ing new languages. monolinguals relied more on regions typically associated Summary of functional and structural effects of bilin - with executive control such as the DLPFC, ACC, SMA, gual experience for tasks and neural regions associated and LCN, while bilinguals only showed increased activa- with speech perception and production. tion in the putamen. Given that the putamen is associated with phonologi- Language learning cal processing and articulation [166, 167], the bilingual Functional brain activity advantages for language learning may be connected to the Evidence suggests that bilingual experience may con- effects of language experience on speech processing, in fer benefits for learning new languages beyond the two addition to cognitive control. Consistent with this notion, that are already known, in part, as a result of changes Kaushanskaya and Marian [157] found that bilinguals to executive function [155–160] (see [161] for review). outperformed monolinguals when learning novel words, For example, Kaushanskaya and Marian [159] observed and that better performance was correlated with phono- that bilinguals were better able to learn novel words logical working memory among early bilinguals, but not that had letter-to-sound mappings that diverged from late bilinguals or monolinguals. This was despite the fact those of their known languages. Participants were asked that phonological working memory has been previously to recall words after hearing a novel word from an arti- linked to word learning for monolinguals [168, 169]. The ficial language either with or without its written form. authors propose that because the novel words were pho- In cases where participants read a word with orthogra- nologically dissimilar to the native language (English), phy that conflicted with letter-to-sound mappings of monolinguals and late bilinguals may not have been able known languages, bilinguals were significantly better at to efficiently utilize their phonological working memory inhibiting interference from letter-to-sound mappings to learn them. Early bilinguals, on the other hand, may be of their native tongue, thereby outperforming monolin- able to utilize phonological working memory resources guals. Similarly, Bartolotti and Marian [155] observed more efficiently to learn even non-native-like words. that when participants completed a visual world task and Recall that Spinu and colleagues [131] proposed a simi- were asked to select novel words with phonological over- lar hypothesis, suggesting that more robust subcortical lap with a known language, monolinguals looked more sound encoding could increase the availability of acoustic Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 13 of 24 Table 2 Consequences of bilingualism for speech perception and production Type Region Effect Task Study ACC Functional ACC/SMA Lower > higher proficiency (activation Single word reading Meschyan and Hernandez [149] associated with reading) Frontal cortex/gyrus Functional Speech perception Astheimer et al. [108] Mono ≠ bi (N1 amplitude; largest at word onset, mono only) Mono ≠ bi (P2 positivity in response to Picture-word relatedness (matching vs. Kuipers and Thierry [105] language change, bi only; P2 positivity mismatching) greater for matching than mismatching stimuli, bi only) L IFC Bi > mono (activation) Speech perception Petitto et al. [124] Structural R DLPFC Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter) MFG/IFG Interpreters > control (cortical thickness Proficiency test Mårtensson et al. [139] after training). interpreters ≠ control (+ correlation MFG cortical thickness/ effort; interpreters only) L MFG/L IFG Unbalanced > balanced (cortical thick- Proficiency test Archila-Suerte et al. [142] ness); unbalanced ≠ balanced (− corre- lation foreign accent/MFG surface area) Temporal cortex/gyrus Structural L STG Unbalanced > balanced (cortical thick- Proficiency test Archila-Suerte et al. [142] ness); unbalanced ≠ balanced (− corre- lation foreign accent/STS surface area) STG Interpreters > control (cortical thickness Proficiency test Mårtensson et al. [139] after training). interpreters ≠ control (+ correlation STG cortical thickness/ proficiency; interpreters only) HG Bi > mono (HG volume, gray matter) Ressel et al. [136] Parietal cortex/gyrus Structural R IPL Interpreters < control (white matter) Elmer et al. [87] Occipital cortex/gyrus Structural L MOG/R LOC Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 14 of 24 Table 2 (continued) Type Region Effect Task Study Subcortical Functional Brainstem Sustained selective attention/speech Krizman et al. [111] Bi > mono (ABR consistency); mono ≠ bi perception (+ correlation: ABR/selective attention, bi only) Brainstem Bi > mono (ABR consistency); mono ≠ bi Attentional control/speech perception Krizman et al. [110] (+ correlation: ABR/attentional control and proficiency, bi only) Brainstem Bi > mono (ABR consistency) Speech perception Krizman et al. [113] Brainstem Bi > mono (FFR) Speech perception Skoe et al. [115] Brainstem Bi > mono (FFR) Speech perception Maggu et al. [114] Brainstem Simultaneous > sequential bilinguals (ABR Speech perception Krizman et al. [112] consistency; + correlation bilingual experience/ABR) L putamen L3 > L2 (activation associated with picture Picture naming Abutalebi et al. [41] naming) Putamen Greater > lower proficiency (activation) Single word reading Meschyan and Hernandez [149] Structural Putamen, thalamus, R CN, L globus Bi > mono (gray matter expansion) Burgaleta et al. [145] pallidus putamen Balanced > unbalanced (volume) Proficiency test Archila-Suerte et al. [142] L putamen Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter); simultaneous ≠ sequen- tial bilinguals (+ correlation: gray mat- ter/native-like accent; sequential only). L putamen Bi > mono (gray matter); bi ≠ mono Picture naming Abutalebi et al. [41] (+ correlation: gray matter/L3 profi- ciency; bi only) R Hip Interpreters > control (volume after Proficiency test Mårtensson et al. [139] training). interpreters ≠ control (+ correlation Hip volume/proficiency; interpreters only) Upper corticospinal tract, R CN Interpreters < control (white matter) Elmer et al. [144] Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 15 of 24 Table 2 (continued) Type Region Effect Task Study Multiple/other Functional Bi > mono (ERP amplitude) Selective attention to tones Rämä et al. [109] Bi > mono (early MEG activity showing Oddball paradigm (sound perception) Ferjan Ramírez et al. [125] more acoustic processing of speech stimuli) Bi > mono (bilinguals faster at differentiat - Oddball paradigm (picture-word pairs) Kuipers and Thierry [106] ing languages, as indicated by ERP) Mono ≠ bi (early ERP positivity for Oddball paradigm (picture-word pairs) Kuipers and Thierry [107] semantically matching pictures/words, bi only) IFG, DLPFC, IPL, cerebellum Early bi > late bi (resting functional con- Speech production task Berken et al. [134, 150] nectivity); + correlation (AoA and con- nectivity between L/R IFG for late bi) semantic module (seed: L SMG); phono- Early bi > late bi (resting functional con- Liu et al. [133] logical module (seed: L IFG ) nectivity in both modules) pt Structural CC, IFOF, uncinate fasciculi (UF), SLF Bi > mono (white matter) Pliatsikas et al. [91] SLF, L IFOF, L UF + Correlation (L2 listening experience Kuhl et al. [100] and white matter in UF and anterior IFOF); + correlation (L2 speaking expe- rience and white matter in posterior SLF and IFOF); bi only; mono > bi (white matter) CC, cingulum, AF, L IFOF Bi > mono (white matter); + correlation Rahmani et al. [153] (immersion time and white matter in all but cingulum; bi only) ILF, CC, AF + Correlation (AoA with L IFL, anterior CC, Picture-word matching Nichols and Joanisse [152] AF); + correlation (proficiency with L ILF, R AF, forceps minor of CC) AF Early bi > late bi (white matter) Hämäläinen et al. [154] CC, L anterior insula Interpreters < control (white matter) Elmer et al. [144] Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 16 of 24 signals in auditory sensory memory. This could in turn the IFG, SFG, and STG, which have been associated with allow for more effective recruitment of phonological managing phonological, syntactic, and semantic interfer- working memory, facilitating discrimination of unfamil- ence between languages. Greater functional connectiv- iar phonetic contrasts, and potentially, the acquisition of ity among similar regions (as well as the DMN) has been novel vocabulary. shown to predict how well individuals are able to learn novel words [183]. Given that bilinguals were found to Structural brain matter have greater connectivity within the DMN as well [71], Bilingual experience has been shown to elicit structural structural and functional changes associated with know- changes in regions that support language processing ing multiple languages could potentially facilitate the and acquisition. The first discovery of neurostructural acquisition of additional languages. changes as a result of bilingual experience was reported As previously discussed, one of the most consist- by Mechelli et al. [170], who observed increased gray ently observed effects of bilingualism on white matter matter density in the posterior supramarginal gyrus integrity is in the IFOF [70, 92, 93, 152, 154], the ventral (pSMG; located in the LIPC) for bilinguals compared to stream of the language processing network implicated in monolinguals. The LIPC has been associated with a num - the semantic processing of language [184]. Nichols and ber of functions relevant to language learning, including Joanisse [152] found that, among bilinguals, age of acqui- the maintenance of mental representations, verbal and sition and proficiency were independently correlated phonological working memory, the integration of seman- with FA values in different tracts. While age of acquisi - tic and phonological information, and cognitive con- tion was uniquely and positively associated with bilateral trol [171–176]. Extending Mechelli et al.’s [170] finding, inferior longitudinal fasciculi (ILF) and otherwise pri- Grogan et al. [177] observed increased gray matter in the marily left-lateralized regions, such as of the CC and the pSMG for multilinguals of three or more languages rela- AF, proficiency was uniquely and positively associated tive to bilinguals, indicating that experience-dependent with corresponding right-lateralized regions. The authors changes to this region can vary by the degree of multi- conjecture that the former may reflect the increased lingualism in addition to categorical differences between effort of utilizing an L2 learned later in life, while the lat - monolinguals and bilinguals. Indeed, gray matter density ter may indicate greater efficiency resulting from mas - in the LIPC has been shown to be negatively correlated tery over the language. They additionally point out that with age of acquisition and positively correlated with lan- the relationship between white matter integrity and pro- guage competence among bilinguals [170, 178]. Further- ficiency may either be causally related (such that greater more, Della Rosa et al. [178] observed that the amount proficiency leads to the development of more robust of gray matter was positively associated with cognitive white matter tracts), or else that certain individuals control, as assessed by an Attentional Network Task. may be predisposed to both greater proficiency and the Consistent with the previously discussed neuroprotec- development of higher white matter integrity. Similarly tive function of bilingualism, Abutalebi et al. [179] found ambiguous is whether there is indeed a causal relation- that while monolinguals displayed age-related gray mat- ship between the effects of bilingual experience on struc - ter reductions in the right inferior parietal lobule, no age- tural changes and the ability to acquire new languages related decline was observed for bilinguals. (e.g., L3, L4). Determining the nature of this relationship There is also evidence of greater gray matter volume is particularly difficult when comparing life-long bilin - for older bilinguals compared to monolinguals in the guals and monolinguals, as the two groups naturally vary temporal pole [180], which for bilinguals, is positively in a number of ways other than language experience and correlated with the ability to name pictures in L2 [181]. neural structures. Establishing the causal links between Grogan et al. [177] similarly observed a positive correla- (1) language experience and changes to neural structures, tion between gray matter density in the LIFG and lexical and (2) neural structures and language learning will likely efficiency (as assessed by a lexical decision task), as well require more longitudinal research, as well as controlled as a negative correlation between gray matter and age of experiments that explicitly manipulate language experi- acquisition. While language is generally associated with ence and track outcomes for later learning. left-lateralized regions, Hosoda et al. [77] found that L2 While few studies have employed true random assign- vocabulary size was positively correlated with gray mat- ment to manipulate language experience coupled with ter density in the right IFG, as well as greater white mat- assessments of later language learning, there are several ter integrity in a number of language-related networks. longitudinal studies examining pre- and post-training García-Pentón et al. [182] similarly observed that bilin- correlates of language ability [77, 139, 185]. Stein et al. guals have greater structural connectivity in a number [185] tested English-speaking exchange students learn- of networks that support language processing, including ing German on day 1 of their stay in Switzerland as well Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 17 of 24 Table 3 Consequences of bilingualism for language learning Type Region Effect Task Study ACC Functional ACC/SMA Mono > bi (activation) L2 word learning Bradley et al. [165] Structural ACC + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) Frontal cortex/gyrus Functional R DLPFC Mono > bi (activation) L2 word learning Bradley et al. [165] Structural IFG + Correlation: gray & white English vocabulary test Hosoda et al. [77] matter/L2 vocabulary size (non-training & training) training > control (gray & white matter) Frontal lobe Bi > mono (white matter) Olsen et al. [180] L IFG Bi only: + correlation: gray L2 proficiency Stein et al. [185] matter/improvement of L2 proficiency IFG; L MFG Interpreters > control (C T L2 proficiency Mårtensson et al. [139] change from T1 to T2) Temporal cortex/gyrus Structural STG/R MTG + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) L temporal lobule Bi > mono (gray matter); Picture naming Abutalebi et al. [181] mono ≠ bi (− correlation: bilingualism/effects of aging) Temporal pole Mono ≠ bi (− correlation: Olsen et al. [180] cortical thickness/aging; mono only) Temporal lobe Bi > mono (white matter) Olsen et al. [180] STG Interpreters > control (C T L2 proficiency Mårtensson et al. [139] change from T1 to T2) Parietal cortex/gyrus Functional L IPL Bi only: + correlation gray ANT, language compe- Della Rosa et al. [178] matter/linguistic compe- tence test tence & cognitive control Structural IPL Bi > mono (gray matter); Vocabulary/linguistic back- Abutalebi et al. [78, 179] mono ≠ bi (− correla- ground measures tion: RIPL gray mat- ter/age, mono only); higher > lower profi- ciency (LIPL gray matter); greater > less exposure (RIPL gray matter) pSMG Multi > bi (gray matter Lexical decision Grogan et al. [177] density) pSMG Bi > mono (gray matter); bi L2 proficiency Mechelli et al. [170] only: (+ correlation: gray matter/L2 proficiency) Subcortical Functional Putamen Bi ≠ mono (bi right puta- Proficiency tests Cherodath et al. [166] men, mono both) Putamen Bi > mono (activation) L2 word learning Bradley et al. [165] L CN Mono > bi (activation) L2 word learning Bradley et al. [165] Structural CN + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) Putamen, thalamas, globus Bi > mono (expansion), cor- Proficiency test Pliatsikas et al. [86] pallidus relation between immer- sion L2 and structure, not proficiency, in sequential bilinguals Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 18 of 24 Table 3 (continued) Type Region Effect Task Study Multiple/other Functional Learning Brocanto2 Grey et al. [164] Bi ≠ mono (bis showed language native-like EEG responses at low proficiency of artificial language when monos did not, bis better RT and accuracy, reached proficiency sooner than monos) Structural Frontal/temporal/parietal Bi > mono (write matter García-Pentón et al. [182] and occipital/temporal/ connectivity in sub- parietal networks) L IFOF, AC-OL Simultaneous bi > mono & Mohades et al. [92] sequential bi (white mat- ter; IFOF) Simultaneous bi < mono (white mater, AC-OL) R IFG/caudate + Correlation: white matter English vocabulary test Hosoda et al. [77] connectivity/L2 vocabu- lary size (non-training and training) training > control L IFOF Simultaneous bi > monolin- Mohades et al. [93] guals (white matter) R IFOF, anterior thalamic Mono > bi (white matter) Reading test Cummine and Boliek [98] radiation Hippocampus Interpreters > control L2 proficiency Mårtensson et al. [139] (volume change from T1 to T2) as 5 months later when proficiency was significantly systematically consider the interactions among linguis- increased. They observed a significant positive correla - tic, contextual, and neurocognitive factors in order to tion between proficiency and gray matter density in the understand how language acquisition shapes the brain IFG, but no relationship between the absolute values and how particular structures support further learning. of density and proficiency at either time point. Hosoda Table 3 provides an overview of studies on the effects et al. [77] similarly observed training-induced increases of bilingualism on language learning and associated in gray and white matter in the right IFG as well as neural regions. increased white matter in the IFG-caudate tract, which Summary of functional and structural effects of bilin - correlated with improvements in proficiency com - gual experience for tasks and neural regions associated pared to a control group. However, as with Stein et al. with language learning. no correlation between pre-training gray/white matter In sum, bilingual experience can lead to a num- and later proficiency gains was observed. These stud - ber of structural changes to language-related brain ies provide strong evidence that language training can areas, including the LIPC, LIFG, and LATL, as well induce neuroplastic changes, though they did not pro- as white matter tracts connecting language-relevant vide evidence that existing neural structures predicted regions. While it is yet unclear whether such changes subsequent language learning abilities. In contrast, a can account for bilinguals’ improved language learn- number of studies have identified neural predictors of ing, people with multilingual experience often develop enhanced learning, including greater volume in the HG neural characteristics associated with better language [138] and greater frontal–parietal connectivity [132], ability in general. Similarly, bilingual experience can both of which have been shown to increase with mul- enhance cognitive functions that support language tilingual experience [70, 136]. It should be noted that acquisition, such as phonological working memory in addition to different findings across studies, there and the ability to inhibit interference from known lan- were differences in methodology (e.g., training peri - guages. It is therefore possible that the greater capacity ods ranging from 1 day to 5 months) and conceptual to learn new languages brings the effects of bilingualism scope (e.g., assessments of syntactic versus linguistic full circle: the need to manage greater linguistic compe- pitch learning). This variability highlights the need to tition is likely at the origin of numerous neurocognitive Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 19 of 24 inferior occipital gyrus; IPC: inferior parietal cortex; IPL: inferior parietal lobe; changes that may ultimately make it easier for bilin- ITG: inferior temporal gyrus; L: left; L2: second language; L3: third language; guals to acquire and control more competitors. LOC: lateral occipital cortex; MEG: magnetoencephalography; MFG: middle frontal gyrus; MOG: middle occipital gyrus; MTG: middle temporal gyrus; PFC: prefrontal cortex; pSMG: posterior supramarginal gyrus; R: right; SMA: sup- Conclusion plementary motor area; SFG: superior frontal gyrus; SLF: superior longitudinal A lifetime of managing multiple linguistic systems can fasciculi; SOG: superior occipital gyrus; STG: superior temporal gyrus; STS: superior temporal sulcus; UF: uncinate fasciculi; WM: white matter. have dramatic effects on both the function and structure of the bilingual neural architecture. Perhaps most sur- Authors’ contributions prising is the discovery that such changes can develop Both authors contributed to the preparation of the manuscript. Both authors read and approved the final manuscript. with relatively brief amounts of exposure to another lan- guage, highlighting the incredible plasticity of the human brain even into adulthood. The increased demands of Acknowledgements We thank Bennett Nicholas Magliato for assistance with preparing the tables controlling competition from candidates of multiple lan- and the members of the Bilingualism and Psycholinguistics Research Group for guages have been shown to alter how bilinguals engage in their helpful comments. high-level processes such as executive control as well as Competing interests low-level perceptual encoding of sound, including in the The authors declare that they have no competing interests. brainstem. Furthermore, we provide evidence that these effects are likely related, such that top-down attentional Availability of data and materials Not applicable. control may in fact contribute to how lower-level sensory functions operate. These often-beneficial changes at vari - Consent for publication ous levels of processing may, in turn, confer advantages Not applicable. for language learning. Ethics approval and consent to participate The human brain is comprised of highly interactive Not applicable. networks that adapt to serve multiple functions. It would Funding therefore be useful to consider the neural consequences Preparation of this manuscript was supported in part by the National Institute of language experience in a similarly interrelated and of Child Health and Human Development (Grant 2R01 HD059858) to VM. comprehensive manner by studying the reciprocal rela- tionships between different language inputs and levels Publisher’s Note of processing. Given that multilingualism is increasingly Springer Nature remains neutral with regard to jurisdictional claims in pub- lished maps and institutional affiliations. the norm rather than the exception, any model of our linguistic capacity would be incomplete without account- Received: 3 January 2019 Accepted: 16 March 2019 ing for how the brain accommodates multiple languages and the subsequent changes that ripple throughout the neurocognitive system. While a number of studies have investigated the effects of bilingualism on one, or at most, References 1. Thomson H. The “sea-nomad” children who see like dolphins. BBC; two functions at a time (for example, cognitive control 2016. http://www.bbc.com/futur e/story /20160 229-the-sea-nomad and speech perception, or cognitive control and language -child ren-who-see-like-dolph ins. Accessed 28 Nov 2018. learning), even greater integration of tasks tapping into 2. Gislén A, Dacke M, Kröger RH, Abrahamsson M, Nilsson D-E, Warrant EJ. Superior underwater vision in a human population of sea gypsies. Curr different processes could offer a more unified view. By Biol. 2003;13:833–6. https ://doi.org/10.1016/S0960 -9822(03)00290 -2. examining the impact of multilingualism at multiple lev- 3. Maguire EA, Gadian DG, Johnsrude IS, Good CD, Ashburner J, Frackow- els of processing, future work may further illuminate the iak RSJ, et al. Navigation-related structural change in the hippocampi of taxi drivers. PNAS. 2000;97:4398–403. https ://doi.org/10.1073/ interconnected and cascading effects of language experi - pnas.07003 9597. ence that result in widespread consequences for cogni- 4. Gong D, He H, Liu D, Ma W, Dong L, Luo C, et al. Enhanced functional tion and the brain. connectivity and increased gray matter volume of insula related to action video game playing. Sci Rep. 2015;5:9763. https ://doi. org/10.1038/srep0 9763. 5. Driemeyer J, Boyke J, Gaser C, Büchel C, May A. Changes in gray matter Abbreviations induced by learning—revisited. PLoS ONE. 2008;3:e2669. https ://doi. ABR: auditory brainstem response; ACC : anterior cingulate cortex; AC-OL: org/10.1371/journ al.pone.00026 69. anterior third of corpus callosum; AF: arcuate fasciculi; Amg: amygdala; ATL: 6. Penfield W, Roberts L. Speech and brain mechanisms. Princeton: Prince - anterior temporal lobe; BAPSS: bilingual anterior to posterior and subcortical ton University Press; 1959. shift; BEPA: bilingual executive processing advantage; BICA: bilingual inhibitory 7. Macnamara J. The bilingual’s linguistic performance—a psy- control advantage; Cb: cerebellum; CC: corpus callosum; CN: caudate nucleus; chological overview. J Soc Issues. 1967;23:58–77. https ://doi. CRN: correct response negativity; DLPFC: dorsolateral prefrontal cortex; EEG: org/10.1111/j.1540-4560.1967.tb005 76.x. electroencephalogram; ERN: error-related negativity; ERP: event-related poten- 8. Gonzales K, Byers-Heinlein K, Lotto AJ. How bilinguals perceive speech tial; FFR: frequency following response; fMRI: functional magnetic resonance depends on which language they think they’re hearing. Cognition. imaging; HG: Heschel’s gyrus; Hip: hippocampus; IFG: inferior frontal gyrus; 2019;182:318–30. https ://doi.org/10.1016/j.cogni tion.2018.08.021. IFOF: inferior frontal-occipital fasciculi; ILF: inferior longitudinal fasciculi; IOG: Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 20 of 24 9. Molnar M, Ibáñez-Molina A, Carreiras M. Interlocutor identity affects 30. Morales L, Paolieri D, Dussias PE, Kroff JRV, Gerfen C, Bajo MT. The language activation in bilinguals. J Mem Lang. 2015;81:91–104. https :// gender congruency effect during bilingual spoken-word recognition. doi.org/10.1016/j.jml.2015.01.002. Bilingualism. 2016;19:294–310. https ://doi.org/10.1017/S1366 72891 10. Quam C, Creel SC. Mandarin-English bilinguals process lexical tones in 50001 76. newly learned words in accordance with the language context. PLoS 31. Kroll JF, Bobb SC, Misra M, Guo T. Language selection in bilingual ONE. 2017;12:e0169001. https ://doi.org/10.1371/journ al.pone.01690 01. speech: Evidence for inhibitory processes. Acta Psychol (Amst). 11. Shook A, Marian V. The influence of native-language tones on lexical 2008;128:416–30. https ://doi.org/10.1016/j.actps y.2008.02.001. access in the second language. J Acoust Soc Am. 2016;139:3102–9. 32. Green DW, Abutalebi J. Language control in bilinguals: The adap- https ://doi.org/10.1121/1.49536 92. tive control hypothesis. J Cogn Psychol. 2013;25:515–30. https ://doi. 12. Spivey MJ, Marian V. Cross talk between native and second languages: org/10.1080/20445 911.2013.79637 7. partial activation of an irrelevant lexicon. Psychol Sci. 1999;10:281– 33. Abutalebi J, Green DW. Neuroimaging of language control in bilinguals: 4. https ://doi.org/10.1111/1467-9280.00151 . neural adaptation and reserve. Bilingualism. 2016;19:689–98. https :// 13. Shook A, Marian V. Bimodal bilinguals co-activate both languages dur-doi.org/10.1017/S1366 72891 60002 25. ing spoken comprehension. Cognition. 2012;124:314–24. https ://doi. 34. Branzi FM, Calabria M, Boscarino ML, Costa A. On the overlap between org/10.1016/j.cogni tion.2012.05.014. bilingual language control and domain-general executive control. 14. Weber A, Cutler A. Lexical competition in non-native spoken-word Acta Psychol (Amst). 2016;166:21–30. https ://doi.org/10.1016/j.actps recognition. J Mem Lang. 2004;50:1–25. https ://doi.org/10.1016/S0749 y.2016.03.001. -596X(03)00105 -0. 35. Hernandez AE, Martinez A, Kohnert K. In search of the language switch: 15. Blumenfeld HK, Marian V. Constraints on parallel activation in bilingual an fMRI study of picture naming in Spanish-English bilinguals. Brain spoken language processing: Examining proficiency and lexical status Lang. 2000;73:421–31. https ://doi.org/10.1006/brln.1999.2278. using eye-tracking. Lang Cogn Process. 2007;22:633–60. https ://doi. 36. Hernandez AE. Language switching in the bilingual brain: what’s org/10.1080/01690 96060 10007 46. next? Brain Lang. 2009;109:133–40. https ://doi.org/10.1016/j.bandl 16. Marian V, Spivey M, Hirsch J. Shared and separate systems in bilingual .2008.12.005. language processing: converging evidence from eyetracking and brain 37. Garbin G, Costa A, Sanjuan A, Forn C, Rodriguez-Pujadas A, Ventura N, imaging. Brain Lang. 2003;86:70–82. https ://doi.org/10.1016/S0093 et al. Neural bases of language switching in high and early proficient -934X(02)00535 -7. bilinguals. Brain Lang. 2011;119:129–35. https ://doi.org/10.1016/j.bandl 17. Marian V, Spivey M. Bilingual and monolingual processing of compet- .2011.03.011. ing lexical items. Appl Psycholinguist. 2003;24:173–93. https ://doi. 38. Seo R, Stocco A, Prat CS. The bilingual language network: differential org/10.1017/S0142 71640 30000 92. involvement of anterior cingulate, basal ganglia and prefrontal cortex in 18. Ju M, Luce PA. Falling on sensitive ears: Constraints on bilingual preparation, monitoring, and execution. Neuroimage. 2018;174:44–56. lexical activation. Psychol Sci. 2004;15:314–8. https ://doi.org/10.111https ://doi.org/10.1016/j.neuro image .2018.02.010. 1/j.0956-7976.2004.00675 .x. 39. Abutalebi J, Green DW. Control mechanisms in bilingual language pro- 19. Cutler A, Weber A, Otake T. Asymmetric mapping from phonetic to lexi- duction: neural evidence from language switching studies. Lang Cogn cal representations in second-language listening. J Phon. 2006;34:269– Process. 2008;23:557–82. https ://doi.org/10.1080/01690 96080 19206 02. 84. https ://doi.org/10.1016/j.wocn.2005.06.002. 40. Zou L, Ding G, Abutalebi J, Shu H, Peng D. Structural plasticity of the left 20. Giezen MR, Blumenfeld HK, Shook A, Marian V, Emmorey K. Parallel caudate in bimodal bilinguals. Cortex. 2012;48:1197–206. https ://doi. language activation and inhibitory control in bimodal bilinguals. Cogni-org/10.1016/j.corte x.2011.05.022. tion. 2015;141:9–25. https ://doi.org/10.1016/j.cogni tion.2015.04.009. 41. Abutalebi J, Della Rosa PA, Castro Gonzaga AK, Keim R, Costa A, Perani 21. Thierry G, Wu YJ. Electrophysiological evidence for language interfer- D. The role of the left putamen in multilingual language produc- ence in late bilinguals. Neuroreport. 2004;15:1555–8. https ://doi. tion. Brain Lang. 2013;125:307–15. https ://doi.org/10.1016/j.bandl org/10.1097/01.wnr.00001 34214 .57469 .c2. .2012.03.009. 22. Hoshino N, Thierry G. Do Spanish-English bilinguals have their fingers 42. Stocco A, Lebiere C, Anderson JR. Conditional routing of information to in two pies—or is it their toes? An electrophysiological investigation the cortex: a model of the basal ganglia’s role in cognitive coordination. of semantic access in bilinguals. Front Psychol. 2012;3:9. https ://doi. Psychol Rev. 2010;117:541–74. https ://doi.org/10.1037/a0019 077. org/10.3389/fpsyg .2012.00009 . 43. Bialystok E, Craik FIM, Luk G. Bilingualism: consequences for mind 23. Chen P, Bobb SC, Hoshino N, Marian V. Neural signatures of language and brain. Trends Cogn Sci. 2012;16:240–50. https ://doi.org/10.1016/j. co-activation and control in bilingual spoken word comprehen- tics.2012.03.001. sion. Brain Res. 2017;1665:50–64. https ://doi.org/10.1016/j.brain 44. Bialystok E, Martin MM, Viswanathan M. Bilingualism across the lifespan: res.2017.03.023. The rise and fall of inhibitory control. Int J Biling. 2005;9:109–19. https :// 24. Carrasco-Ortiz H, Midgley KJ, Frenck-Mestre C. Are phonological repre-doi.org/10.1177/13670 06905 00900 10701 . sentations in bilinguals language specific? An ERP study on interlingual 45. Marian V, Chabal S, Bartolotti J, Bradley K, Hernandez AE. Differential homophones. Psychophysiology. 2012;49:531–43. https ://doi.org/10.11 recruitment of executive control regions during phonological competi- 11/j.1469-8986.2011.01333 .x. tion in monolinguals and bilinguals. Brain Lang. 2014;139:108–17. https 25. Guo T, Peng D. Event-related potential evidence for parallel activa-://doi.org/10.1016/j.bandl .2014.10.005. tion of two languages in bilingual speech production. Neuroreport. 46. Abutalebi J, Della Rosa PA, Green DW, Hernandez M, Scifo P, Keim R, 2006;17:1757–60. https ://doi.org/10.1097/01.wnr.00002 46327 .89308 .a5. et al. Bilingualism tunes the anterior cingulate cortex for conflict moni- 26. Thierry G, Wu YJ. Brain potentials reveal unconscious translation during toring. Cereb Cortex. 2012;22:2076–86. https ://doi.org/10.1093/cerco r/ foreign-language comprehension. Proc Natl Acad Sci. 2007;104:12530–bhr28 7. 5. https ://doi.org/10.1073/pnas.06099 27104 . 47. Garbin G, Sanjuan A, Forn C, Bustamante JC, Rodriguez-Pujadas A, Bel- 27. Allopenna PD, Magnuson JS, Tanenhaus MK. Tracking the time course loch V, et al. Bridging language and attention: brain basis of the impact of spoken word recognition using eye movements: Evidence for of bilingualism on cognitive control. Neuroimage. 2010;53:1272–8. continuous mapping models. J Mem Lang. 1998;38:419–39. https ://doi.https ://doi.org/10.1016/j.neuro image .2010.05.078. org/10.1006/jmla.1997.2558. 48. Becker TM, Prat CS, Stocco A. A network-level analysis of cognitive 28. Huettig F, Rommers J, Meyer AS. Using the visual world paradigm flexibility reveals a differential influence of the anterior cingulate cortex to study language processing: A review and critical evaluation. Acta in bilinguals versus monolinguals. Neuropsychologia. 2016;85:62–73. Psychol (Amst). 2011;137:151–71. https ://doi.org/10.1016/j.actps https ://doi.org/10.1016/j.neuro psych ologi a.2016.01.020. y.2010.11.003. 49. Dong Y, Zhong F. Interpreting experience enhances early attentional 29. Macizo P, Bajo T, Cruz Martín M. Inhibitory processes in bilingual processing, conflict monitoring and interference suppression along the language comprehension: Evidence from Spanish-English interlexical time course of processing. Neuropsychologia. 2017;95:193–203. https :// homographs. J Mem Lang. 2010;63:232–44. https ://doi.org/10.1016/j.doi.org/10.1016/j.neuro psych ologi a.2016.12.007. jml.2010.04.002. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 21 of 24 50. Kałamała P, Drożdżowicz A, Szewczyk J, Marzecová A, Wodniecka Z. 69. Waldie KE, Badzakova-Trajkov G, Miliivojevic B, Kirk IJ. Neural activ- Task strategy may contribute to performance differences between ity during Stroop colour-word task performance in late proficient monolinguals and bilinguals in cognitive control tasks: ERP evidence. bilinguals: a functional Magnetic Resonance Imaging study. Psychol J Neurolinguistics. 2018;46:78–92. https ://doi.org/10.1016/j.jneur oling Neurosci. 2009;2:125–36. https ://doi.org/10.3922/j.psns.2009.2.004. .2017.12.013. 70. Luk G, Bialystok E, Craik FIM, Grady CL. Lifelong bilingualism maintains 51. Kousaie S, Phillips NA. Conflict monitoring and resolution: Are two white matter integrity in older adults. J Neurosci. 2011;31:16808– languages better than one? Evidence from reaction time and event- 13. https ://doi.org/10.1523/JNEUR OSCI.4563-11.2011. related brain potentials. Brain Res. 2012;1446:71–90. https ://doi. 71. Grady CL, Luk G, Craik FIM, Bialystok E. Brain network activity in mono- org/10.1016/j.brain res.2012.01.052. lingual and bilingual older adults. Neuropsychologia. 2015;66:170– 52. Morales J, Yudes C, Gómez-Ariza CJ, Bajo MT. Bilingualism modulates 81. https ://doi.org/10.1016/j.neuro psych ologi a.2014.10.042. dual mechanisms of cognitive control: evidence from ERPs. Neuropsy- 72. Buckner RL, Sepulcre J, Talukdar T, Krienen FM, Liu H, Hedden T, et al. chologia. 2015;66:157–69. https ://doi.org/10.1016/j.neuro psych ologi Neurobiology of disease cortical hubs revealed by intrinsic functional a.2014.11.014. connectivity: mapping, assessment of stability, and relation to Alzhei- 53. Nieuwenhuis S, Yeung N, van den Wildenberg W, Ridderinkhof KR. Elec- mer’s disease. J Neurosci. 2009;29:1860–73. https ://doi.org/10.1523/ trophysiological correlates of anterior cingulate function in a go/no-go JNEUR OSCI.5062-08.2009. task: effects of response conflict and trial type frequency. Cogn Aec ff t 73. Dang LC, O’Neil JP, Jagust WJ. Genetic effects on behavior are mediated Behav Neurosci. 2003;3:17–26. https ://doi.org/10.3758/CABN.3.1.17. by neurotransmitters and large-scale neural networks. Neuroimage. 54. Falkenstein M, Hoormann J, Hohnsbein J. Inhibition-related 2013;66:203–14. https ://doi.org/10.1016/j.neuro image .2012.10.090. ERP components: Variation with modality, age, and time-on- 74. Cole MW, Reynolds JR, Power JD, Repovs G, Anticevic A, Braver TS. Multi- task. EBSCOhost. J Psychophysiol. 2002;16:167–75. https ://doi. task connectivity reveals flexible hubs for adaptive task control. Nat org/10.1027//0269-8803.16.3.167. Neurosci. 2013;16:1348–55. https ://doi.org/10.1038/nn.3470. 55. Melara RD, Wang H, Vu KPL, Proctor RW. Attentional origins of the 75. Olulade OA, Jamal NI, Koo DS, Perfetti CA, LaSasso C, Eden GF. Neu- Simon effect: Behavioral and electrophysiological evidence. Brain Res. roanatomical evidence in support of the bilingual advantage theory. 2008;1215:147–59. https ://doi.org/10.1016/j.brain res.2008.03.026. Cereb Cortex. 2016;26:3196–204. https ://doi.org/10.1093/cerco r/bhv15 56. Mathalon DH, Whitfield SL, Ford JM. Anatomy of an error: ERP and 2. fMRI. Biol Psychol. 2003;64:119–41. https ://doi.org/10.1016/S0301 76. Hervais-Adelman A, Egorova N, Golestani N. Beyond bilingualism: mul- -0511(03)00105 -4. tilingual experience correlates with caudate volume. Brain Struct Funct. 57. Fernandez M, Tartar JL, Padron D, Acosta J. Neurophysiological marker 2018;223:3495–502. https ://doi.org/10.1007/s0042 9-018-1695-0. of inhibition distinguishes language groups on a non-linguistic execu- 77. Hosoda C, Tanaka K, Nariai T, Honda M, Hanakawa T. Dynamic neural tive function test. Brain Cogn. 2013;83:330–6. https ://doi.org/10.1016/j. network reorganization associated with second language vocabulary bandc .2013.09.010. acquisition: a multimodal imaging study. J Neurosci. 2013;33:13663–72. 58. Moreno S, Wodniecka Z, Tays W, Alain C, Bialystok E. Inhibitory control https ://doi.org/10.1523/JNEUR OSCI.0410-13.2013. in bilinguals and musicians: event related potential (ERP) evidence 78. Abutalebi J, Guidi L, Borsa V, Canini M, Della Rosa PA, Parris BA, et al. for experience-specific effects. PLoS ONE. 2014;9:e94169. https ://doi. Bilingualism provides a neural reserve for aging populations. Neuropsy- org/10.1371/journ al.pone.00941 69. chologia. 2015;69:201–10. https ://doi.org/10.1016/j.neuro psych ologi 59. Kousaie S, Phillips NA. A behavioural and electrophysiological inves- a.2015.01.040. tigation of the effect of bilingualism on aging and cognitive control. 79. Miller EK, Cohen JD. An integrative theory of prefrontal cortex function. Neuropsychologia. 2017;94:23–35. https ://doi.org/10.1016/j.neuro psych Annu Rev Neurosci. 2001;24:167–202. https ://doi.org/10.1146/annur ologi a.2016.11.013.ev.neuro .24.1.167. 60. Hilchey MD, Klein RM. Are there bilingual advantages on nonlinguistic 80. Hernandez AE, Dapretto M, Mazziotta J, Bookheimer S. Language interference tasks? Implications for the plasticity of executive control switching and language representation in Spanish-English bilinguals: processes. Psychon Bull Rev. 2011;18:625–58. https ://doi.org/10.3758/ an fMRI study. Neuroimage. 2001;14:510–20. https ://doi.org/10.1006/ s1342 3-011-0116-7. nimg.2001.0810. 61. Coderre EL, van Heuven WJB. Electrophysiological explorations of 81. Alladi S, Bak TH, Duggirala V, Surampudi B, Shailaja M, Shukla AK, et al. the bilingual advantage: evidence from a stroop task. PLoS ONE. Bilingualism delays age at onset of dementia, independent of educa- 2014;9:e103424. https ://doi.org/10.1371/journ al.pone.01034 24. tion and immigration status. Neurology. 2013;81:1938–44. https ://doi. 62. Heidlmayr K, Hemforth B, Moutier S, Isel F. Neurodynamics of executive org/10.1212/01.wnl.00004 36620 .33155 .a4. control processes in bilinguals: evidence from ERP and source recon- 82. Bialystok E, Craik FIM, Freedman M. Bilingualism as a protection against struction analyses. Front Psychol. 2015;6:821. https ://doi.org/10.3389/ the onset of symptoms of dementia. Neuropsychologia. 2007;45:459– fpsyg .2015.00821 /abstr act. 64. https ://doi.org/10.1016/j.neuro psych ologi a.2006.10.009. 63. Anderson JAE, Chung-Fat-Yim A, Bellana B, Luk G, Bialystok E. Language 83. Botvinick M, Nystrom LE, Fissell K, Carter CS, Cohen JD. Conflict moni- and cognitive control networks in bilinguals and monolinguals. Neu- toring versus selection-for-action in anterior cingulate cortex. Nature. ropsychologia. 2018;117:352–63. https ://doi.org/10.1016/j.neuro psych 1999;402:179–81. https ://doi.org/10.1038/46035 . ologi a.2018.06.023. 84. Wang Y, Xue G, Chen C, Xue F, Dong Q. Neural bases of asymmetric 64. Coderre EL, Smith JF, Van Heuven WJB, Horwitz B. The functional language switching in second-language learners: An ER-fMRI study. overlap of executive control and language processing in bilinguals. Neuroimage. 2007;35:862–70. https ://doi.org/10.1016/j.neuro image Bilingualism. 2016;19:471–88. https ://doi.org/10.1017/S1366 72891 .2006.09.054. 50001 88. 85. Deluca V, Rothman J, Pliatsikas C. Linguistic immersion and structural 65. Timmer K, Grundy JG, Bialystok E. Earlier and more distributed neural effects on the bilingual brain: a longitudinal study. Biling Lang Cogn. networks for bilinguals than monolinguals during switching. Neuropsy- 2018. https ://doi.org/10.1017/S1366 72891 80008 83. chologia. 2017;106:245–60. https ://doi.org/10.1016/j.neuro psych ologi 86. Pliatsikas C, DeLuca V, Moschopoulou E, Saddy JD. Immersive bilingual- a.2017.09.017. ism reshapes the core of the brain. Brain Struct Funct. 2017;222:1785– 66. Grundy JG, Anderson JAE, Bialystok E. Neural correlates of cogni- 95. https ://doi.org/10.1007/s0042 9-016-1307-9. tive processing in monolinguals and bilinguals. Ann N Y Acad Sci. 87. Elmer S, Hänggi J, Jäncke L. Processing demands upon cognitive, 2017;1396:183–201. https ://doi.org/10.1111/nyas.13333 . linguistic, and articulatory functions promote grey matter plasticity in 67. Marian V, Bartolotti J, Rochanavibhata S, Bradley K, Hernandez AE. Bilin- the adult multilingual brain: insights from simultaneous interpreters. gual cortical control of between- and within-language competition. Sci Cortex. 2014;54:179–89. https ://doi.org/10.1016/j.corte x.2014.02.014. Rep. 2017;7:11763. https ://doi.org/10.1038/s4159 8-017-12116 -w. 88. Filippi R, Richardson FM, Dick F, Leech R, Green DW, Thomas MSC, et al. 68. Grundy JG, Anderson JAE, Bialystok E. Bilinguals have more complex The right posterior paravermis and the control of language interfer- EEG brain signals in occipital regions than monolinguals. Neuroimage. ence. J Neurosci. 2011;31:10732–40. https ://doi.org/10.1523/JNEUR 2017;159:280–8. https ://doi.org/10.1016/j.neuro image .2017.07.063. OSCI.1783-11.2011. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 22 of 24 89. Pliatsikas C, Johnstone T, Marinis T. Grey matter volume in the cerebel- 109. Rämä P, Leminen A, Koskenoja-Vainikka S, Leminen M, Alho K, Kujala T. lum is related to the processing of grammatical rules in a second Eec ff t of language experience on selective auditory attention: an event- language: a structural voxel-based morphometry study. Cerebellum. related potential study. Int J Psychophysiol. 2018;127:38–45. https ://doi. 2014;13:55–63. https ://doi.org/10.1007/s1231 1-013-0515-6.org/10.1016/j.ijpsy cho.2018.03.007. 90. Schlegel AA, Rudelson JJ, Tse PU. White matter structure changes as 110. Krizman J, Skoe E, Marian V, Kraus N. Bilingualism increases neural adults learn a second language. J Cogn Neurosci. 2012;24:1664–70. response consistency and attentional control: evidence for sensory https ://doi.org/10.1162/jocn_a_00240 . and cognitive coupling. Brain Lang. 2014;128:34–40. https ://doi. 91. Pliatsikas C, Moschopoulou E, Saddy JD. The effects of bilingualism on org/10.1016/j.bandl .2013.11.006. the white matter structure of the brain. PNAS. 2015;112:1334–7. https :// 111. Krizman J, Marian V, Shook A, Skoe E, Kraus N. Subcortical encoding doi.org/10.1073/pnas.14141 83112 . of sound is enhanced in bilinguals and relates to executive func- 92. Mohades SG, Struys E, Van Schuerbeek P, Mondt K, Van De Craen P, tion advantages. Proc Natl Acad Sci. 2012;109:7877–81. https ://doi. Luypaert R. DTI reveals structural differences in white matter tracts org/10.1073/pnas.12015 75109 . between bilingual and monolingual children. Brain Res. 2012;1435:72– 112. Krizman J, Slater J, Skoe E, Marian V, Kraus N. Neural processing of 80. https ://doi.org/10.1016/j.brain res.2011.12.005. speech in children is influenced by extent of bilingual experience. Neu- 93. Mohades SG, Van Schuerbeek P, Rosseel Y, Van De Craen P, Luypaert rosci Lett. 2015;585:48–53. https ://doi.org/10.1016/j.neule t.2014.11.011. R, Baeken C. White-matter development is different in bilingual 113. Krizman J, Skoe E, Kraus N. Bilingual enhancements have no socioeco- and monolingual children: a longitudinal DTI study. PLoS ONE. nomic boundaries. Dev Sci. 2016;19:881–91. https ://doi.org/10.1111/ 2015;10:e0117968. https ://doi.org/10.1371/journ al.pone.01179 68. desc.12347 . 94. Zhang J, Zhu X, Wang X, Gao J, Shi H, Huang B, et al. Increased structural 114. Maggu AR, Zong W, Law V, Wong PCM. Learning two tone languages connectivity in corpus callosum in adolescent males with conduct enhances the brainstem encoding of lexical tones. Proc Interspeech. disorder. J Am Acad Child Adolesc Psychiatry. 2014;53(466.e1):475.e1. 2018;2018:1437–41. https ://doi.org/10.21437 /Inter speec h.2018-2130. https ://doi.org/10.1016/j.jaac.2013.12.015. 115. Skoe E, Burakiewicz E, Figueiredo M, Hardin M. Basic neural processing 95. Just MA, Cherkassky VL, Keller TA, Kana RK, Minshew NJ. Functional and of sound in adults is influenced by bilingual experience. Neuroscience. anatomical cortical underconnectivity in autism: evidence from an fMRI 2017;349:278–90. https ://doi.org/10.1016/j.neuro scien ce.2017.02.049. study of an executive function task and corpus callosum morphometry. 116. Song JH, Skoe E, Wong PCM, Kraus N. Plasticity in the adult human Cereb Cortex. 2007;17:951–61. https ://doi.org/10.1093/cerco r/bhl00 6. auditory brainstem following short-term linguistic training. J Cogn 96. Duffau H. The anatomo-functional connectivity of language revisited: Neurosci. 2008;20:1892–902. https ://doi.org/10.1162/jocn.2008.20131 . New insights provided by electrostimulation and tractography. Neu- 117. Krishnan A, Xu Y, Gandour J, Cariani P. Encoding of pitch in the human ropsychologia. 2008;46:927–34. https ://doi.org/10.1016/j.neuro psych brainstem is sensitive to language experience. Cogn Brain Res. ologi a.2007.10.025. 2005;25:161–8. https ://doi.org/10.1016/j.cogbr ainre s.2005.05.004. 97. Almairac F, Herbet G, Moritz-Gasser S, de Champfleur NM, Duffau H. The 118. Anderson S, Skoe E, Chandrasekaran B, Zecker S, Kraus N. Brainstem left inferior fronto-occipital fasciculus subserves language semantics: correlates of speech-in-noise perception in children. Hear Res. a multilevel lesion study. Brain Struct Funct. 2015;220:1983–95. https :// 2010;270:151–7. https ://doi.org/10.1016/j.heare s.2010.08.001. doi.org/10.1007/s0042 9-014-0773-1. 119. Song JH, Skoe E, Banai K, Kraus N. Perception of speech in noise: Neural 98. Cummine J, Boliek CA. Understanding white matter integrity stability correlates. J Cogn Neurosci. 2011;23:2268–79. https ://doi.org/10.1162/ for bilinguals on language status and reading performance. Brain Struct jocn.2010.21556 . Funct. 2013;218:595–601. https ://doi.org/10.1007/s0042 9-012-0466-6. 120. Krishnan A, Gandour JT, Bidelman GM. The effects of tone language 99. Gold BT, Johnson NF, Powell DK. Lifelong bilingualism contributes to experience on pitch processing in the brainstem. J Neurolinguistics. cognitive reserve against white matter integrity declines in aging. Neu- 2010;23:81–95. https ://doi.org/10.1016/j.jneur oling .2009.09.001. ropsychologia. 2013;51:2841–6. https ://doi.org/10.1016/j.neuro psych 121. Zhao TC, Kuhl PK. Linguistic effect on speech perception observed at ologi a.2013.09.037. the brainstem. Proc Natl Acad Sci. 2018;115:201800186. https ://doi. 100. Kuhl PK, Stevenson J, Corrigan NM, van den Bosch JJF, Can DD, Richards org/10.1073/pnas.18001 86115 . T. Neuroimaging of the bilingual brain: structural brain correlates of 122. Strange W, Jenkins JJ. Role of linguistic experience in the per- listening and speaking in a second language. Brain Lang. 2016;162:1–9. ception of speech. Perception Exp. 1978;1:129–69. https ://doi. https ://doi.org/10.1016/j.bandl .2016.07.004. org/10.1007/978-1-4684-2619-9_5. 101. Douet V, Chang L. Fornix as an imaging marker for episodic memory 123. Bidelman GM, Gandour JT, Krishnan A. Cross-domain effects of music deficits in healthy aging and in various neurological disorders. Front and language experience on the representation of pitch in the human Aging Neurosci. 2015;6:343. https ://doi.org/10.3389/fnagi .2014.00343 / auditory brainstem. J Cogn Neurosci. 2011;23:425–34. https ://doi. abstr act. org/10.1162/jocn.2009.21362 . 102. Ye Z, Zhou X. Executive control in language processing. Neurosci 124. Petitto LA, Berens MS, Kovelman I, Dubins MH, Jasinska K, Shalinsky M. Biobehav Rev. 2009;33:1168–77. https ://doi.org/10.1016/j.neubi The “Perceptual Wedge Hypothesis” as the basis for bilingual babies’ orev.2009.03.003. phonetic processing advantage: new insights from fNIRS brain imag- 103. Anderson MC, Green C. Suppressing unwanted memories by executive ing. Brain Lang. 2012;121:130–43. https ://doi.org/10.1016/j.bandl control. Nature. 2014;410:366–9. https ://doi.org/10.1038/35066 572. .2011.05.003. 104. Wardlow L. Individual differences in speakers’ perspective taking: the 125. Ferjan Ramírez N, Ramírez RR, Clarke M, Taulu S, Kuhl PK. Speech roles of executive control and working memory. Psychon Bull Rev. discrimination in 11-month-old bilingual and monolingual infants: a 2013;20:766–72. https ://doi.org/10.3758/s1342 3-013-0396-1. magnetoencephalography study. Dev Sci. 2017;20:e12427. https ://doi. 105. Kuipers J-R, Thierry G. Event-related brain potentials reveal the time- org/10.1111/desc.12427. course of language change detection in early bilinguals. Neuroimage. 126. Singh L. Bilingual infants demonstrate advantages in learning words in 2010;50:1633–8. https ://doi.org/10.1016/j.neuro image .2010.01.076. a third language. Child Dev. 2018;89:e397–413. https ://doi.org/10.1111/ 106. Kuipers JR, Thierry G. Event-related potential correlates of language cdev.12852. change detection in bilingual toddlers. Dev Cogn Neurosci. 2012;2:97– 127. Tremblay M-C, Sabourin L. Comparing behavioral discrimination and 102. https ://doi.org/10.1016/j.dcn.2011.08.002. learning abilities in monolinguals, bilinguals and multilinguals. J Acoust 107. Kuipers JR, Thierry G. Bilingualism and increased attention to speech: Soc Am. 2012;132:3465–74. https ://doi.org/10.1121/1.47569 55. evidence from event-related potentials. Brain Lang. 2015;149:27–32. 128. Werker JF. The effect of multilingualism on phonetic perceptual flexibil- https ://doi.org/10.1016/j.bandl .2015.07.004. ity. Appl Psycholinguist. 1986;7:141–55. https ://doi.org/10.1017/S0142 108. Astheimer LB, Berkes M, Bialystok E. Differential allocation of atten-71640 00073 60. tion during speech perception in monolingual and bilingual listeners. 129. Antoniou M, Liang E, Ettlinger M, Wong PCM. The bilingual advan- Lang Cogn Neurosci. 2016;31:196–205. https ://doi.org/10.1080/23273 tage in phonetic learning. Bilingualism. 2015;18:683–95. https ://doi. 798.2015.10831 14.org/10.1017/S1366 72891 40007 77. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 23 of 24 130. Wang T, Saffran JR. Statistical learning of a tonal language: the influ- Neuroimage. 2006;29:1135–40. https ://doi.org/10.1016/j.neuro image ence of bilingualism and previous linguistic experience. Front Psychol. .2005.08.055. 2014;5:1–9. https ://doi.org/10.3389/fpsyg .2014.00953 . 150. Berken JA, Gracco VL, Chen JK, Klein D. The timing of language learning 131. Spinu LE, Hwang J, Lohmann R. Is there a bilingual advantage in shapes brain structure associated with articulation. Brain Struct Funct. phonetic and phonological acquisition? The initial learning of word- 2016;221:3591–600. https ://doi.org/10.1007/s0042 9-015-1121-9. final coronal stop realization in a novel accent of English. Int J Biling. 151. Dick AS, Tremblay P. Beyond the arcuate fasciculus: consensus 2018;22:350–70. https ://doi.org/10.1177/13670 06916 68108 0. and controversy in the connectional anatomy of language. Brain. 132. Ventura-Campos N, Sanjuán A, González J, Ngeles Palomar-García M-A, 2012;135:3529–50. https ://doi.org/10.1093/brain /aws22 2. Rodríguez-Pujadas A, Sebastián-Gallés N, et al. Spontaneous brain activ- 152. Nichols ES, Joanisse MF. Functional activity and white matter micro- ity predicts learning ability of foreign sounds. J Neurosci. 2013;33:9295– structure reveal the independent effects of age of acquisition and pro - 305. https ://doi.org/10.1523/JNEUR OSCI.4655-12.2013. ficiency on second-language learning. Neuroimage. 2016;143:15–25. 133. Liu X, Tu L, Wang J, Jiang B, Gao W, Pan X, et al. Onset age of L2 acquisi-https ://doi.org/10.1016/j.neuro image .2016.08.053. tion influences language network in early and late Cantonese-Man- 153. Rahmani F, Sobhani S, Aarabi MH. Sequential language learning and darin bilinguals. Brain Lang. 2017;174:16–28. https ://doi.org/10.1016/j. language immersion in bilingualism: diffusion MRI connectometry bandl .2017.07.003. reveals microstructural evidence. Exp Brain Res. 2017;235:2935–45. 134. Berken JA, Chai X, Chen J-K, Gracco VL, Klein D. Eec ff ts of Early and https ://doi.org/10.1007/s0022 1-017-5029-x. Late Bilingualism on Resting-State Functional Connectivity. J Neurosci. 154. Hämäläinen S, Sairanen V, Leminen A, Lehtonen M. Bilingualism 2016;36:1165–72. https ://doi.org/10.1523/JNEUR OSCI.1960-15.2016. modulates the white matter structure of language-related pathways. 135. Callan DE, Kawato M, Parsons L, Turner R. Speech and song: the Neuroimage. 2017;152:249–57. https ://doi.org/10.1016/j.neuro image role of the cerebellum. Cerebellum. 2007;6:321–7. https ://doi. .2017.02.081. org/10.1080/14734 22060 11877 33. 155. Bartolotti J, Marian V. Language learning and control in monolinguals 136. Ressel V, Pallier C, Ventura-Campos N, Diaz B, Roessler A, Avila C, and bilinguals. Cogn Sci. 2012;36:1129–47. https ://doi.org/10.111 et al. An effect of bilingualism on the auditory cortex. J Neurosci. 1/j.1551-6709.2012.01243 .x. 2012;32:16597–601. https ://doi.org/10.1523/JNEUR OSCI.1996-12.2012. 156. Bartolotti J, Marian V, Schroeder SR, Shook A. Bilingualism and inhibitory 137. Golestani N, Molko N, Dehaene S, LeBihan D, Pallier C. Brain struc- control influence statistical learning of novel word forms. Front Psychol. ture predicts the learning of foreign speech sounds. Cereb Cortex. 2011;2:1–10. https ://doi.org/10.3389/fpsyg .2011.00324 . 2007;17:575–82. https ://doi.org/10.1093/cerco r/bhk00 1. 157. Kaushanskaya M, Marian V. Age-of-acquisition effects in the develop - 138. Wong PCM, Warrier CM, Penhune VB, Roy AK, Sadehh A, Parrish TB, et al. ment of a bilingual advantage for word learning. In: Proceedings of the Volume of left Heschl’s gyrus and linguistic pitch learning. Cereb Cortex. 32nd annual Boston University conference on language development; 2008;18:828–36. https ://doi.org/10.1093/cerco r/bhm11 5. 2007. p. 213–24. https ://pdfs.seman ticsc holar .org/c880/0a8f1 cf5e1 139. Mårtensson J, Eriksson J, Bodammer NC, Lindgren M, Johansson 038b3 af377 2821f d8b33 4785f 0.pdf. Accessed 20 Nov 2018. M, Nyberg L, et al. Growth of language-related brain areas after 158. Kaushanskaya M, Marian V. The bilingual advantage in novel word foreign language learning. Neuroimage. 2012;63:240–4. https ://doi. learning. Psychon Bull Rev. 2009;16:705–10. https ://doi.org/10.3758/ org/10.1016/j.neuro image .2012.06.043. PBR.16.4.705. 140. Price CJ. The anatomy of language: a review of 100 fMRI studies pub- 159. Kaushanskaya M, Marian V. Bilingualism reduces native-language inter- lished in 2009. Ann NY Acad Sci. 2010;1191:62–88. https ://doi.org/10.11 ference during novel-word learning. J Exp Psychol Learn Mem Cogn. 11/j.1749-6632.2010.05444 .x. 2009;35:829–35. https ://doi.org/10.1037/a0015 275. 141. Hu X, Ackermann H, Martin JA, Erb M, Winkler S, Reiterer SM. Language 160. Keshavarz MH, Astaneh H. The impact of bilinguality on the learning of aptitude for pronunciation in advanced second language (L2) learners: English vocabulary as a foreign language (L3). Int J Biling Educ Biling. behavioural predictors and neural substrates. Brain Lang. 2013;127:366– 2004;7:295–302. https ://doi.org/10.1080/13670 05040 86678 14. 76. https ://doi.org/10.1016/j.bandl .2012.11.006. 161. Hirosh Z, Degani T. Direct and indirect effects of multilingualism on 142. Archila-Suerte P, Woods EA, Chiarello C, Hernandez AE. Neuroanatomi- novel language learning: an integrative review. Psychon Bull Rev. cal profiles of bilingual children. Dev Sci. 2018;21:e12654. https ://doi. 2018;25:892–916. https ://doi.org/10.3758/s1342 3-017-1315-7. org/10.1111/desc.12654 . 162. Cox JG. Explicit instruction, bilingualism, and the older adult learner. 143. Rodriguez SM, Archila-Suerte P, Vaughn KA, Chiarello C, Hernandez Stud Second Lang Acquis. 2017;39:29–58. https ://doi.org/10.1017/ AE. Anterior insular thickness predicts speech sound learning ability S0272 26311 50003 64. in bilinguals. Neuroimage. 2018;165:278–84. https ://doi.org/10.1016/j. 163. Nation R, Mclaughlin B. Novices and experts: an information processing neuro image .2017.10.038. approach to the “good language learner” problem. Appl Psycholinguist. 144. Elmer S, Rgen Hänggi J, Meyer M, Jäncke L. Differential language 1986;7:41–55. https ://doi.org/10.1017/S0142 71640 00071 77. expertise related to white matter architecture in regions subserving 164. Grey S, Sanz C, Morgan-Short K, Ullman MT. Bilingual and monolingual sensory-motor coupling, articulation, and interhemispheric transfer. adults learning an additional language: ERPs reveal differences in Hum Brain Mapp. 2011;32:2064–74. https ://doi.org/10.1002/hbm.21169 syntactic processing. Biling Lang Cogn. 2018;21:970–94. https ://doi. .org/10.1017/S1366 72891 70004 26. 145. Burgaleta M, Sanjuán A, Ventura-Campos N, Sebastian-Galles N, Ávila 165. Bradley KAL, King KE, Hernandez AE. Language experience differenti- C. Bilingualism at the core of the brain. Structural differences between ates prefrontal and subcortical activation of the cognitive control bilinguals and monolinguals revealed by subcortical shape analysis. network in novel word learning. Neuroimage. 2013;67:101–10. https :// Neuroimage. 2016;125:437–45. https ://doi.org/10.1016/j.neuro image doi.org/10.1016/j.neuro image .2012.11.018. .2015.09.073. 166. Cherodath S, Rao C, Midha R, Sumathi TA, Singh NC. A role for putamen 146. Klein D, Zatorre RJ, Milner B, Meyer E, Evans AC. Left putaminal activa- in phonological processing in children. Biling Lang Cogn. 2017;20:318– tion when speaking a second language. Neuroreport. 1994;5:2295–7. 26. https ://doi.org/10.1017/S1366 72891 60006 14. https ://doi.org/10.1097/00001 756-19941 1000-00022 . 167. Tettamanti M, Moro A, Messa C, Moresco RM, Rizzo G, Carpinelli A, et al. 147. Robles SG, Gatignol P, Capelle L, Mitchell MC, Duffau H. The role of Basal ganglia and language: phonology modulates dopaminergic dominant striatum in language: a study using intraoperative electrical release. NeuroReport. 2005;16:397–401. https ://doi.org/10.1097/00001 stimulations. J Neurol Neurosurg Psychiatry. 2005;76:940–6. https ://doi.756-20050 3150-00018 . org/10.1136/jnnp.2004.04594 8. 168. Masoura EV, Gathercole SE. Phonological short-term memory and 148. Gurd JM, Bessell NJ, Bladon RAW, Bamford JM. A case of foreign foreign language learning. Int J Psychol. 1999;34:383–8. https ://doi. accent syndrome, with follow-up clinical, Neuropsychological and org/10.1080/00207 59993 99738 . phonetic descriptions. Neuropsychologia. 1988;26:237–51. https ://doi. 169. Papagno C, Valentine T, Baddeley A. Phonological short-term memory org/10.1016/0028-3932(88)90077 -2. and foreign-language vocabulary learning. J Mem Lang. 1991;30:331– 149. Meschyan G, Hernandez AE. Impact of language proficiency and ortho - 47. https ://doi.org/10.1016/0749-596X(91)90040 -Q. graphic transparency on bilingual word reading: an fMRI investigation. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 24 of 24 170. Mechelli A, Crinion JT, Noppeney U, O’Doherty J, Ashburner J, Frackow- 179. Abutalebi J, Canini M, Della Rosa PA, Green DW, Weekes BS. The neu- iak RS, et al. Neurolinguistics: structural plasticity in the bilingual brain. roprotective effects of bilingualism upon the inferior parietal lobule: a Nature. 2004;431:757. https ://doi.org/10.1038/43175 7a. structural neuroimaging study in aging chinese bilinguals. J Neurolin- 171. Abutalebi J, Green D. Bilingual language production: The neurocog- guistics. 2015;33:3–13. https ://doi.org/10.1016/j.jneur oling .2014.09.008. nition of language representation and control. J Neurolinguistics. 180. Olsen RK, Pangelinan MM, Bogulski C, Chakravarty MM, Luk G, Grady 2007;20:242–75. https ://doi.org/10.1016/j.jneur oling .2006.10.003. CL, et al. The effect of lifelong bilingualism on regional grey and white 172. Baddeley A. Working memory: looking back and looking forward. Nat matter volume. Brain Res. 2015;1612:128–39. https ://doi.org/10.1016/j. Rev Neurosci. 2003;4:829–39. https ://doi.org/10.1038/nrn12 01.brain res.2015.02.034. 173. Bunge SA, Hazeltine E, Scanlon MD, Rosen AC, Gabrieli JDE. Disso- 181. Abutalebi J, Canini M, Della Rosa PA, Sheung LP, Green DW, Weekes ciable contributions of prefrontal and parietal cortices to response BS. Bilingualism protects anterior temporal lobe integrity in aging. selection. Neuroimage. 2002;17:1562–71. https ://doi.org/10.1006/ Neurobiol Aging. 2014;35:2126–33. https ://doi.org/10.1016/j.neuro biola nimg.2002.1252. ging.2014.03.010. 174. Lee H, Devlin JT, Shakeshaft C, Stewart LH, Brennan A, Glensman J, 182. García-Pentón L, Pérez Fernández A, Iturria-Medina Y, Gillon-Dowens et al. Anatomical traces of vocabulary acquisition in the adolescent M, Carreiras M. Anatomical connectivity changes in the bilingual brain. brain. J Neurosci. 2007;27:1184–9. https ://doi.org/10.1523/JNEUR Neuroimage. 2014;84:495–504. https ://doi.org/10.1016/j.neuro image OSCI.4442-06.2007. .2013.08.064. 175. Price CJ, Green DW, von Studnitz R. A functional imaging study of 183. Veroude K, Norris D, Shumskaya E, Gullberg M, Indefrey P. Functional translation and language switching. Brain. 1999;122:2221–35. https :// connectivity between brain regions involved in learning words of a doi.org/10.1093/brain /122.12.2221. new language. Brain Lang. 2010;113:21–7. https ://doi.org/10.1016/j. 176. Vigneau M, Beaucousin V, Hervé PY, Duffau H, Crivello F, Houdé O, et al. bandl .2009.12.005. Meta-analyzing left hemisphere language areas: phonology, semantics, 184. Mandonnet E, Nouet A, Gatignol P, Capelle L, Duffau H. Does the left and sentence processing. Neuroimage. 2006;30:1414–32. https ://doi. inferior longitudinal fasciculus play a role in language? A brain stimula- org/10.1016/j.neuro image .2005.11.002. tion study. Brain. 2007;130:623–9. https ://doi.org/10.1093/brain /awl36 1. 177. Grogan AO, Parker Jones T, Ali N, Crinion J, Orabona S, Mechias ML, et al. 185. Stein M, Federspiel A, Koenig T, Wirth M, Strik W, Wiest R, et al. Structural Structural correlates for lexical efficiency and number of languages in plasticity in the language system related to increased second language non-native speakers of English. Neuropsychologia. 2012;50:1347–52. proficiency. Cortex. 2012;48:458–65. https ://doi.org/10.1016/j.corte https ://doi.org/10.1016/j.neuro psych ologi a.2012.02.019. x.2010.10.007. 178. Della Rosa PA, Videsott G, Borsa VM, Canini M, Weekes BS, Franceschini R, et al. A neural interactive location for multilingual talent. 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References (197)

J. Abutalebi, D. Green (2016)
Neuroimaging of language control in bilinguals: neural adaptation and reserve
Bilingualism: Language and Cognition, 19
J. Driemeyer, J. Boyke, Christian Gaser, C. Büchel, A. May (2008)
Changes in Gray Matter Induced by Learning—Revisited
PLoS ONE, 3
Gabrielle Garbin, A. Sanjuán, C. Forn, J. Bustamante, A. Rodríguez-Pujadas, V. Belloch, M. Hernández, Albert Costa, C. Ávila (2010)
Bridging language and attention: Brain basis of the impact of bilingualism on cognitive control
NeuroImage, 53
P. Wong, C. Warrier, V. Penhune, Anil Roy, Abdulmalek Sadehh, T. Parrish, R. Zatorre (2008)
Volume of left Heschl's Gyrus and linguistic pitch learning.
Cerebral cortex, 18 4
G. Thierry, Y. Wu (2004)
Electrophysiological evidence for language interference in late bilinguals
NeuroReport, 15
John Anderson, Ashley Chung-Fat-Yim, Buddhika Bellana, G. Luk, E. Bialystok (2018)
Language and cognitive control networks in bilinguals and monolinguals
Neuropsychologia, 117
M. Burgaleta, A. Sanjuán, N. Ventura‐Campos, N. Sebastián-Gallés, C. Ávila (2016)
Bilingualism at the core of the brain. Structural differences between bilinguals and monolinguals revealed by subcortical shape analysis
NeuroImage, 125
Noriko Hoshino, G. Thierry (2012)
Do Spanish–English Bilinguals have Their Fingers in Two Pies – or is It Their Toes? An Electrophysiological Investigation of Semantic Access in Bilinguals
Frontiers in Psychology, 3
Gayane Meschyan, Arturo Hernandez (2006)
Impact of language proficiency and orthographic transparency on bilingual word reading: An fMRI investigation
NeuroImage, 29
Haydée Carrasco-Ortíz, Katherine Midgley, C. Frenck-Mestre (2012)
Are phonological representations in bilinguals language specific? An ERP study on interlingual homophones.
Psychophysiology, 49 4
Jessica Cox (2015)
EXPLICIT INSTRUCTION, BILINGUALISM, AND THE OLDER ADULT LEARNER
Studies in Second Language Acquisition, 39
D. Callan, M. Kawato, L. Parsons, R. Turner (2008)
Speech and song: The role of the cerebellum
The Cerebellum, 6
Anna Gislén, M. Dacke, R. Kröger, M. Abrahamsson, D. Nilsson, E. Warrant (2003)
Superior Underwater Vision in a Human Population of Sea Gypsies
Current Biology, 13
R. Nation, B. Mclaughlin (1986)
Novices and experts: An information processing approach to the “good language learner” problem
Applied Psycholinguistics, 7
James Bartolotti, Viorica Marian, Scott Schroeder, Anthony Shook (2011)
Bilingualism and Inhibitory Control Influence Statistical Learning of Novel Word Forms
Frontiers in Psychology, 2
Jennifer Krizman, J. Slater, E. Skoe, Viorica Marian, N. Kraus (2015)
Neural processing of speech in children is influenced by extent of bilingual experience
Neuroscience Letters, 585
N. Ventura‐Campos, A. Sanjuán, Julio González, María-Ángeles Palomar-García, A. Rodríguez-Pujadas, N. Sebastián-Gallés, G. Deco, C. Ávila (2013)
Spontaneous Brain Activity Predicts Learning Ability of Foreign Sounds
The Journal of Neuroscience, 33
K. Timmer, J. Grundy, E. Bialystok (2017)
Earlier and more distributed neural networks for bilinguals than monolinguals during switching
Neuropsychologia, 106
Lijuan Zou, Guosheng Ding, J. Abutalebi, H. Shu, D. Peng (2012)
Structural plasticity of the left caudate in bimodal bilinguals
Cortex, 48
A. Dick, Pascale Tremblay (2012)
Beyond the arcuate fasciculus: consensus and controversy in the connectional anatomy of language.
Brain : a journal of neurology, 135 Pt 12
Arturo Hernandez (2009)
Language switching in the bilingual brain: What’s next?
Brain and Language, 109
J. Abutalebi, D. Green (2008)
Control mechanisms in bilingual language production: Neural evidence from language switching studies
Language and Cognitive Processes, 23
Hweeling Lee, J. Devlin, Clare Shakeshaft, L. Stewart, A. Brennan, Jen Glensman, Katherine Pitcher, J. Crinion, A. Mechelli, R. Frackowiak, D. Green, C. Price (2007)
Anatomical Traces of Vocabulary Acquisition in the Adolescent Brain
The Journal of Neuroscience, 27
Benjamin Young, Andreas Keller, D. Rosenthal (2014)
Quality-space theory in olfaction
Frontiers in Psychology, 5
R. Melara, Huijun Wang, K. Vu, R. Proctor (2008)
Attentional origins of the Simon effect: Behavioral and electrophysiological evidence
Brain Research, 1215
C. Pliatsikas, Elisavet Moschopoulou, J. Saddy (2015)
The effects of bilingualism on the white matter structure of the brain
Proceedings of the National Academy of Sciences, 112
S. Robles, P. Gatignol, L. Capelle, M-C Mitchell, H. Duffau (2005)
The role of dominant striatum in language: a study using intraoperative electrical stimulations
Journal of Neurology, Neurosurgery & Psychiatry, 76
M Ju, PA Luce (2004)
Falling on sensitive ears: Constraints on bilingual lexical activation
Psychol Sci., 15
S. Elmer, J. Hänggi, M. Meyer, L. Jäncke (2011)
Differential language expertise related to white matter architecture in regions subserving sensory‐motor coupling, articulation, and interhemispheric transfer
Human Brain Mapping, 32
M. Molnar, A. Ibáñez-Molina, M. Carreiras (2015)
Interlocutor identity affects language activation in bilinguals
Journal of Memory and Language, 81
J. Kuipers, G. Thierry (2015)
Bilingualism and increased attention to speech: Evidence from event-related potentials
Brain and Language, 149
J. Morales, Carolina Yudes, Carlos Gomez-Ariza, M. Bajo (2015)
Bilingualism modulates dual mechanisms of cognitive control: Evidence from ERPs
Neuropsychologia, 66
Leher Singh (2018)
Bilingual Infants Demonstrate Advantages in Learning Words in a Third Language.
Child development, 89 4
Xiaochen Hu, H. Ackermann, J. Martin, M. Erb, S. Winkler, S. Reiterer (2013)
Language aptitude for pronunciation in advanced second language (L2) Learners: Behavioural predictors and neural substrates
Brain and Language, 127
M. Vigneau, V. Beaucousin, P. Hervé, H. Duffau, F. Crivello, O. Houdé, B. Mazoyer, B. Mazoyer, N. Tzourio-Mazoyer (2006)
Meta-analyzing left hemisphere language areas: Phonology, semantics, and sentence processing
NeuroImage, 30
RL Buckner, J Sepulcre, T Talukdar, FM Krienen, H Liu, T Hedden (2009)
Neurobiology of disease cortical hubs revealed by intrinsic functional connectivity: mapping, assessment of stability, and relation to Alzheimer’s disease
J Neurosci, 29
G. Luk, E. Bialystok, F. Craik, C. Grady (2011)
Lifelong Bilingualism Maintains White Matter Integrity in Older Adults
The Journal of Neuroscience, 31
Sylvain Moreno, Z. Wodniecka, William Tays, Claude Alain, E. Bialystok (2014)
Inhibitory Control in Bilinguals and Musicians: Event Related Potential (ERP) Evidence for Experience-Specific Effects
PLoS ONE, 9
Anthony Shook, Viorica Marian (2012)
Bimodal bilinguals co-activate both languages during spoken comprehension
Cognition, 124
Farzaneh Rahmani, S. Sobhani, M. Aarabi (2017)
Sequential language learning and language immersion in bilingualism: diffusion MRI connectometry reveals microstructural evidence
Experimental Brain Research, 235
Francesca Branzi, M. Calabria, Maria Boscarino, Albert Costa (2016)
On the overlap between bilingual language control and domain-general executive control.
Acta psychologica, 166
R. Olsen, Melissa Pangelinan, C. Bogulski, M. Chakravarty, G. Luk, C. Grady, E. Bialystok (2015)
The effect of lifelong bilingualism on regional grey and white matter volume
Brain Research, 1612
E. Nichols, M. Joanisse (2016)
Functional activity and white matter microstructure reveal the independent effects of age of acquisition and proficiency on second-language learning
NeuroImage, 143
G. Garbin, Albert Costa, A. Sanjuán, Cristina Forn, A. Rodríguez-Pujadas, Noelia Ventura, V. Belloch, Mireia Hernández, César Ávila (2011)
Neural bases of language switching in high and early proficient bilinguals
Brain and Language, 119
J. Grundy, John Anderson, E. Bialystok (2017)
Bilinguals have more complex EEG brain signals in occipital regions than monolinguals
NeuroImage, 159
A. Mechelli, J. Crinion, U. Noppeney, J. O’Doherty, J. Ashburner, Richard Frackowiak, C. Price (2004)
Neurolinguistics: Structural plasticity in the bilingual brain
Nature, 431
J. Grundy, John Anderson, E. Bialystok (2017)
Neural correlates of cognitive processing in monolinguals and bilinguals
Annals of the New York Academy of Sciences, 1396
J. Kuipers, G. Thierry (2010)
Event-related brain potentials reveal the time-course of language change detection in early bilinguals
NeuroImage, 50
A. Baddeley (2003)
Working memory: looking back and looking forward
Nature Reviews Neuroscience, 4
M. Botvinick, L. Nystrom, K. Fissell, C. Carter, J. Cohen (1999)
Conflict monitoring versus selection-for-action in anterior cingulate cortex
Nature, 402
E. Bialystok, F. Craik, M. Freedman (2007)
Bilingualism as a protection against the onset of symptoms of dementia
Neuropsychologia, 45
Alexis Hervais-Adelman, N. Egorova, N. Golestani (2017)
Beyond bilingualism: multilingual experience correlates with caudate volume
Brain Structure and Function, 223
Roy Seo, Andrea Stocco, C. Prat (2018)
The bilingual language network: Differential involvement of anterior cingulate, basal ganglia and prefrontal cortex in preparation, monitoring, and execution
NeuroImage, 174
J. Abutalebi, M. Canini, P. Rosa, D. Green, B. Weekes (2015)
The neuroprotective effects of bilingualism upon the inferior parietal lobule: A Structural Neuroimaging Study in Aging Chinese Bilinguals
Journal of Neurolinguistics, 33
Judy Song, E. Skoe, K. Banai, N. Kraus (2011)
Perception of Speech in Noise: Neural Correlates
Journal of Cognitive Neuroscience, 23
T. Becker, C. Prat, Andrea Stocco (2016)
A network-level analysis of cognitive flexibility reveals a differential influence of the anterior cingulate cortex in bilinguals versus monolinguals
Neuropsychologia, 85
Yapeng Wang, G. Xue, Chuansheng Chen, Feng Xue, Q. Dong (2007)
Neural bases of asymmetric language switching in second-language learners: An ER-fMRI study
NeuroImage, 35
Margarita Kaushanskaya, Viorica Marian (2007)
Age-of-acquisition effects in the development of a bilingual advantage for word learning
A Krishnan, Y Xu, J Gandour, P Cariani (2005)
Encoding of pitch in the human brainstem is sensitive to language experience
Cogn Brain Res., 25
James Bartolotti, Viorica Marian (2012)
Language Learning and Control in Monolinguals and Bilinguals
Cognitive science, 36 6
L. Petitto, M. Berens, M. Berens, I. Kovelman, M. Dubins, K. Jasińska, Mark Shalinsky (2012)
The “Perceptual Wedge Hypothesis” as the basis for bilingual babies’ phonetic processing advantage: New insights from fNIRS brain imaging
Brain and Language, 121
J. Abutalebi, P. Rosa, Anna Gonzaga, Roland Keim, Albert Costa, D. Perani (2013)
The role of the left putamen in multilingual language production
Brain and Language, 125
Jennifer Krizman, Viorica Marian, Anthony Shook, E. Skoe, N. Kraus (2012)
Subcortical encoding of sound is enhanced in bilinguals and relates to executive function advantages
Proceedings of the National Academy of Sciences, 109
M. Antoniou, Eric Liang, M. Ettlinger, P. Wong (2014)
The bilingual advantage in phonetic learning*
Bilingualism: Language and Cognition, 18
K. Veroude, D. Norris, E. Shumskaya, M. Gullberg, P. Indefrey (2010)
Functional connectivity between brain regions involved in learning words of a new language
Brain and Language, 113
P. Rämä, A. Leminen, Satu Koskenoja-Vainikka, Miika Leminen, K. Alho, T. Kujala (2018)
Effect of language experience on selective auditory attention: An event-related potential study.
International journal of psychophysiology : official journal of the International Organization of Psychophysiology, 127
Zoya Hirosh, T. Degani (2017)
Direct and indirect effects of multilingualism on novel language learning: An integrative review
Psychonomic Bulletin & Review, 25
Jonathan Berken, X. Chai, Jen-Kai Chen, V. Gracco, D. Klein (2016)
Effects of Early and Late Bilingualism on Resting-State Functional Connectivity
The Journal of Neuroscience, 36
Viorica Marian, Michael Spivey, J. Hirsch (2003)
Shared and separate systems in bilingual language processing: Converging evidence from eyetracking and brain imaging
Brain and Language, 86
Diankun Gong, H. He, Dongbo Liu, Weiyi Ma, Li Dong, C. Luo, D. Yao (2015)
Enhanced functional connectivity and increased gray matter volume of insula related to action video game playing
Scientific Reports, 5
Margarita Kaushanskaya, Viorica Marian (2009)
Bilingualism reduces native-language interference during novel-word learning.
Journal of experimental psychology. Learning, memory, and cognition, 35 3
D. Klein, R. Zatorre, B. Milner, E. Meyer, Alan Evans (1994)
Left putaminal activation when speaking a second language: evidence from PET.
Neuroreport, 5 17
Carolyn Quam, Sarah Creel (2017)
Mandarin-English Bilinguals Process Lexical Tones in Newly Learned Words in Accordance with the Language Context
PLoS ONE, 12
K. Bradley, K. King, Arturo Hernandez (2013)
Language experience differentiates prefrontal and subcortical activation of the cognitive control network in novel word learning
NeuroImage, 67
C. Hosoda, Kanji Tanaka, T. Nariai, M. Honda, T. Hanakawa (2013)
Dynamic Neural Network Reorganization Associated with Second Language Vocabulary Acquisition: A Multimodal Imaging Study
The Journal of Neuroscience, 33
Sinikka Hämäläinen, V. Sairanen, A. Leminen, Minna Lehtonen (2017)
Bilingualism modulates the white matter structure of language-related pathways
NeuroImage, 152
Michael Spivey, Viorica Marian (1999)
Cross Talk Between Native and Second Languages: Partial Activation of an Irrelevant Lexicon
Psychological Science, 10
M Falkenstein, J Hoormann, J Hohnsbein (2002)
Inhibition-related ERP components: Variation with modality, age, and time-on-task
EBSCOhost. J Psychophysiol., 16
Lori Astheimer, Matthias Berkes, E. Bialystok (2015)
Differential allocation of attention during speech perception in monolingual and bilingual listeners
Language, Cognition and Neuroscience, 31
Taomei Guo, D. Peng (2006)
Event-related potential evidence for parallel activation of two languages in bilingual speech production
NeuroReport, 17
F. Almairac, G. Herbet, S. Moritz-Gasser, N. Champfleur, H. Duffau (2015)
The left inferior fronto-occipital fasciculus subserves language semantics: a multilevel lesion study
Brain Structure and Function, 220
G Thierry, YJ Wu (2007)
Brain potentials reveal unconscious translation during foreign-language comprehension
Proc Natl Acad Sci., 104
P. Macizo, T. Bajo, María Martín (2010)
Inhibitory processes in bilingual language comprehension: Evidence from Spanish-English interlexical homographs
Journal of Memory and Language, 63
(2004)
Structural plasticity in the bilingual brain: Proficiency in a second language and age at acquisition affect grey-matter density.
J. Abutalebi, D. Green (2007)
Bilingual language production: The neurocognition of language representation and control
Journal of Neurolinguistics, 20
Matthew Hilchey, R. Klein (2011)
Are there bilingual advantages on nonlinguistic interference tasks? Implications for the plasticity of executive control processes
Psychonomic Bulletin & Review, 18
Pilar Archila-Suerte, Elizabeth Woods, C. Chiarello, Arturo Hernandez (2018)
Neuroanatomical profiles of bilingual children.
Developmental science, 21 5
E. Coderre, Jason Smith, Walter HEUVEN, B. Horwitz (2016)
The Functional Overlap of Executive Control and Language Processing in Bilinguals.
Bilingualism, 19 3
E. Mandonnet, A. Nouet, P. Gatignol, L. Capelle, H. Duffau (2007)
Does the left inferior longitudinal fasciculus play a role in language? A brain stimulation study.
Brain : a journal of neurology, 130 Pt 3
Jonathan Berken, V. Gracco, Jen-Kai Chen, D. Klein (2016)
The timing of language learning shapes brain structure associated with articulation
Brain Structure and Function, 221
S. Nieuwenhuis, N. Yeung (2003)
Electrophysiological correlates of anterior cingulate function in a go/no-go task: Effects of response conflict and trial type frequency
Cognitive, Affective, & Behavioral Neuroscience, 3
MA Just, VL Cherkassky, TA Keller, RK Kana, NJ Minshew (2007)
Functional and anatomical cortical underconnectivity in autism: evidence from an fMRI study of an executive function task and corpus callosum morphometry
Cereb Cortex., 17
N Golestani, N Molko, S Dehaene, D LeBihan, C Pallier (2007)
Brain structure predicts the learning of foreign speech sounds
Cereb Cortex., 17
(2006)
Cerebral Cortex doi:10.1093/cercor/bhl006 Functional and Anatomical Cortical Underconnectivity in Autism: Evidence from an fMRI Study of an Executive Function Task and Corpus Callosum
J. Cummine, C. Boliek (2012)
Understanding white matter integrity stability for bilinguals on language status and reading performance
Brain Structure and Function, 218
P. Etchells, C. Benton, Casimir Ludwig, I. Gilchrist (2011)
Testing a Simplified Method for Measuring Velocity Integration in Saccades Using a Manipulation of Target Contrast
Frontiers in Psychology, 2
D. Mathalon, S. Whitfield, J. Ford (2003)
Anatomy of an error: ERP and fMRI
Biological Psychology, 64
Roberto Filippi, Fiona Richardson, F. Dick, R. Leech, D. Green, M. Thomas, C. Price (2011)
The Right Posterior Paravermis and the Control of Language Interference
The Journal of Neuroscience, 31
S. Kousaie, N. Phillips (2012)
Conflict monitoring and resolution: Are two languages better than one? Evidence from reaction time and event-related brain potentials
Brain Research, 1446
A. Cutler, Andrea Weber, Takashi Otake (2006)
Asymmetric mapping from phonetic to lexical representations in second-language listening
J. Phonetics, 34
O. Olulade, N. Jamal, D. Koo, C. Perfetti, C. LaSasso, G. Eden (2016)
Neuroanatomical Evidence in Support of the Bilingual Advantage Theory.
Cerebral cortex, 26 7
Cathy Price, David Green, Roswitha Studnitz (1999)
A functional imaging study of translation and language switching.
Brain : a journal of neurology, 122 ( Pt 12)
Anthony Shook, Viorica Marian (2016)
The influence of native-language tones on lexical access in the second language.
The Journal of the Acoustical Society of America, 139 6
Luis Morales, D. Paolieri, Paola Dussias, Jorge Kroff, Chip Gerfen, M. Bajo (2015)
The gender congruency effect during bilingual spoken-word recognition*
Bilingualism: Language and Cognition, 19
Volker Ressel, Christophe Pallier, N. Ventura‐Campos, B. Díaz, A. Roessler, C. Ávila, N. Sebastián-Gallés (2012)
An Effect of Bilingualism on the Auditory Cortex
The Journal of Neuroscience, 32
(1960)
Speech and Brain‐Mechanisms
Medical Journal of Australia, 1
Xiaojin Liu, Liu Tu, Junjing Wang, Bo Jiang, Weinong Gao, Ximin Pan, Meng Li, Miao Zhong, Zhenzhen Zhu, Meiqi Niu, Yanyan Li, Ling Zhao, Xiaoxi Chen, Chang Liu, Zhi Lu, Ruiwang Huang (2017)
Onset age of L2 acquisition influences language network in early and late Cantonese-Mandarin bilinguals
Brain and Language, 174
The "sea-nomad" children who see like dolphins. BBC
S. Anderson, E. Skoe, B. Chandrasekaran, S. Zecker, N. Kraus (2010)
Brainstem correlates of speech-in-noise perception in children
Hearing Research, 270
Arturo Hernandez, Antígona Martínez, Kathryn Kohnert (2000)
In Search of the Language Switch: An fMRI Study of Picture Naming in Spanish–English Bilinguals
Brain and Language, 73
H. Duffau (2008)
The anatomo-functional connectivity of language revisited New insights provided by electrostimulation and tractography
Neuropsychologia, 46
J. Kroll, Susan Bobb, Maya Misra, Taomei Guo (2008)
Language selection in bilingual speech: evidence for inhibitory processes.
Acta psychologica, 128 3
Elvira Masoura, S. Gathercole (1999)
Phonological Short-term Memory and Foreign Language Learning
International Journal of Psychology, 34
D. Green, J. Abutalebi (2013)
Language control in bilinguals: The adaptive control hypothesis
Journal of Cognitive Psychology (Hove, England), 25
M. Tettamanti, A. Moro, C. Messa, R. Moresco, G. Rizzo, A. Carpinelli, M. Matarrese, F. Fazio, D. Perani (2005)
Basal ganglia and language: phonology modulates dopaminergic release
NeuroReport, 16
A. Grogan, Oiwi Jones, N. Ali, J. Crinion, S. Orabona, M. Mechias, S. Ramsden, D. Green, C. Price (2012)
Structural correlates for lexical efficiency and number of languages in non-native speakers of English
Neuropsychologia, 50
S. Rodriguez, Pilar Archila-Suerte, Kelly Vaughn, C. Chiarello, Arturo Hernandez (2018)
Anterior insular thickness predicts speech sound learning ability in bilinguals
NeuroImage, 165
S. Cherodath, Chaitra Rao, Rashi Midha, S. A, N. Singh (2016)
A role for putamen in phonological processing in children*
Bilingualism: Language and Cognition, 20
G. Bidelman, J. Gandour, Ananthanarayan Krishnan (2011)
Cross-domain Effects of Music and Language Experience on the Representation of Pitch in the Human Auditory Brainstem
Journal of Cognitive Neuroscience, 23
Alexander Schlegel, Justin Rudelson, P. Tse (2012)
White Matter Structure Changes as Adults Learn a Second Language
Journal of Cognitive Neuroscience, 24
E. Maguire, D. Gadian, I. Johnsrude, C. Good, J. Ashburner, Richard Frackowiak, C. Frith (2000)
Navigation-related structural change in the hippocampi of taxi drivers.
Proceedings of the National Academy of Sciences of the United States of America, 97 8
R. Buckner, J. Sepulcre, Tanveer Talukdar, Fenna Krienen, Hesheng Liu, T. Hedden, J. Andrews-Hanna, R. Sperling, Keith Johnson (2009)
Cortical Hubs Revealed by Intrinsic Functional Connectivity: Mapping, Assessment of Stability, and Relation to Alzheimer's Disease
The Journal of Neuroscience, 29
E. Bialystok, Michelle Martin, M. Viswanathan (2005)
Bilingualism across the lifespan: The rise and fall of inhibitory control
International Journal of Bilingualism, 9
S. Elmer, J. Hänggi, L. Jäncke (2014)
Processing demands upon cognitive, linguistic, and articulatory functions promote grey matter plasticity in the adult multilingual brain: Insights from simultaneous interpreters
Cortex, 54
J. Macnamara (1967)
The Bilingual's Linguistic Performance—A Psychological Overview
Journal of Social Issues, 23
Jibiao Zhang, Xueling Zhu, Xiang Wang, Junling Gao, Huqing Shi, Bingsheng Huang, W. Situ, J. Yi, Xiongzhao Zhu, S. Yao (2014)
Increased structural connectivity in corpus callosum in adolescent males with conduct disorder.
Journal of the American Academy of Child and Adolescent Psychiatry, 53 4
Liane Wardlow (2013)
Individual differences in speakers’ perspective taking: The roles of executive control and working memory
Psychonomic Bulletin & Review, 20
M. Falkenstein, J. Hoormann, J. Hohnsbein (2002)
Inhibition-Related ERP Components: Variation with Modality, Age, and Time-on-Task
Journal of Psychophysiology, 16
P. Kałamała, Anna Drożdżowicz, J. Szewczyk, Anna Marzecová, Z. Wodniecka (2018)
Task strategy may contribute to performance differences between monolinguals and bilinguals in cognitive control tasks: ERP evidence
Journal of Neurolinguistics, 46
J. Abutalebi, M. Canini, P. Rosa, Lo Sheung, D. Green, B. Weekes (2014)
Bilingualism protects anterior temporal lobe integrity in aging
Neurobiology of Aging, 35
Paul Allopenna, J. Magnuson, M. Tanenhaus (1998)
Tracking the Time Course of Spoken Word Recognition Using Eye Movements: Evidence for Continuous Mapping Models
Journal of Memory and Language, 38
Z. Ye, Xiaolin Zhou (2009)
Executive control in language processing
Neuroscience & Biobehavioral Reviews, 33
E. Skoe, Emily Burakiewicz, Michael Figueiredo, Margaret Hardin (2017)
Basic neural processing of sound in adults is influenced by bilingual experience
Neuroscience, 349
W. Strange, J. Jenkins (1978)
Role of Linguistic Experience in the Perception of Speech
C. Pliatsikas, T. Johnstone, T. Marinis (2013)
Grey Matter Volume in the Cerebellum is Related to the Processing of Grammatical Rules in a Second Language: A Structural Voxel-based Morphometry Study
Cerebellum (London, England), 13
M. Giezen, H. Blumenfeld, Anthony Shook, Viorica Marian, K. Emmorey (2015)
Parallel language activation and inhibitory control in bimodal bilinguals
Cognition, 141
L. Dang, J. O’Neil, W. Jagust (2013)
Genetic effects on behavior are mediated by neurotransmitters and large-scale neural networks
NeuroImage, 66
Min Ju, P. Luce (2004)
Falling on Sensitive Ears
Psychological Science, 15
Kalim Gonzales, K. Byers‐Heinlein, A. Lotto (2019)
How bilinguals perceive speech depends on which language they think they’re hearing
Cognition, 182
Jennifer Krizman, E. Skoe, Viorica Marian, N. Kraus (2014)
Bilingualism increases neural response consistency and attentional control: Evidence for sensory and cognitive coupling
Brain and Language, 128
H. Blumenfeld, Viorica Marian (2007)
Constraints on parallel activation in bilingual spoken language processing: Examining proficiency and lexical status using eye-tracking
Language and Cognitive Processes, 22
Ananthanarayan Krishnan, J. Gandour, G. Bidelman (2010)
The effects of tone language experience on pitch processing in the brainstem
Journal of Neurolinguistics, 23
B. Gold, N. Johnson, D. Powell (2013)
Lifelong bilingualism contributes to cognitive reserve against white matter integrity declines in aging
Neuropsychologia, 51
E. Miller, J. Cohen (2001)
An integrative theory of prefrontal cortex function.
Annual review of neuroscience, 24
(2006)
Cerebral Cortex doi:10.1093/cercor/bhk001 Brain Structure Predicts the Learning of Foreign Speech Sounds
S. Alladi, T. Bak, V. Duggirala, B. Surampudi, M. Shailaja, A. Shukla, J. Chaudhuri, S. Kaul (2013)
Bilingualism delays age at onset of dementia, independent of education and immigration status
Neurology, 81
J. Werker (1986)
The effect of multilingualism on phonetic perceptual flexibility
Applied Psycholinguistics, 7
CJ Price (2010)
The anatomy of language: a review of 100 fMRI studies published in 2009
Ann NY Acad Sci., 1191
C. Grady, G. Luk, F. Craik, E. Bialystok (2015)
Brain network activity in monolingual and bilingual older adults
Neuropsychologia, 66
Margarita Kaushanskaya, Viorica Marian (2009)
The bilingual advantage in novel word learning
Psychonomic Bulletin & Review, 16
J. Mårtensson, J. Eriksson, N. Bodammer, M. Lindgren, M. Johansson, L. Nyberg, M. Lövdén (2012)
Growth of language-related brain areas after foreign language learning
NeuroImage, 63
V. Deluca, J. Rothman, C. Pliatsikas (2018)
Linguistic immersion and structural effects on the bilingual brain: a longitudinal study
Bilingualism: Language and Cognition, 22
Viorica Marian, James Bartolotti, Sirada Rochanavibhata, K. Bradley, Arturo Hernandez (2017)
Bilingual Cortical Control of Between- and Within-Language Competition
Scientific Reports, 7
Judy Song, E. Skoe, P. Wong, N. Kraus (2008)
Plasticity in the Adult Human Auditory Brainstem following Short-term Linguistic Training
Journal of Cognitive Neuroscience, 20
Jennifer Krizman, E. Skoe, N. Kraus (2016)
Bilingual enhancements have no socioeconomic boundaries.
Developmental science, 19 6
Viorica Marian, S. Chabal, James Bartolotti, K. Bradley, Arturo Hernandez (2014)
Differential recruitment of executive control regions during phonological competition in monolinguals and bilinguals
Brain and Language, 139
S. Mohades, E. Struys, P. Schuerbeek, K. Mondt, P. Craen, R. Luypaert (2012)
DTI reveals structural differences in white matter tracts between bilingual and monolingual children
Brain Research, 1435
P. Kuhl, J. Stevenson, N. Corrigan, J. Bosch, Dilara Can, Todd Richards (2016)
Neuroimaging of the bilingual brain: Structural brain correlates of listening and speaking in a second language
Brain and Language, 162
S. Bunge, E. Hazeltine, M. Scanlon, A. Rosen, J. Gabrieli (2002)
Dissociable Contributions of Prefrontal and Parietal Cortices to Response Selection
NeuroImage, 17
Karin Heidlmayr, Barbara Hemforth, S. Moutier, F. Isel (2015)
Neurodynamics of executive control processes in bilinguals: evidence from ERP and source reconstruction analyses
Frontiers in Psychology, 6
G. Thierry, Y. Wu (2007)
Brain potentials reveal unconscious translation during foreign-language comprehension
Nature Reviews Neuroscience, 8
S. Mohades, P. Schuerbeek, Y. Rosseel, Piet Craen, R. Luypaert, C. Baeken (2015)
White-Matter Development is Different in Bilingual and Monolingual Children: A Longitudinal DTI Study
PLoS ONE, 10
Mercedes Fernandez, J. Tartar, D. Padron, Juliana Acosta (2013)
Neurophysiological marker of inhibition distinguishes language groups on a non-linguistic executive function test
Brain and Cognition, 83
P. Rosa, G. Videsott, V. Borsa, M. Canini, B. Weekes, R. Franceschini, J. Abutalebi (2013)
A neural interactive location for multilingual talent
Cortex, 49
M. Keshavarz, H. Astaneh (2004)
The Impact of Bilinguality on the Learning of English Vocabulary as a Foreign Language (L3)
International Journal of Bilingual Education and Bilingualism, 7
S. Kousaie, N. Phillips (2017)
A behavioural and electrophysiological investigation of the effect of bilingualism on aging and cognitive control
Neuropsychologia, 94
Peiyao Chen, Susan Bobb, Noriko Hoshino, Viorica Marian (2017)
Neural signatures of language co-activation and control in bilingual spoken word comprehension
Brain Research, 1665
C. Price (2010)
The anatomy of language: a review of 100 fMRI studies published in 2009
Annals of the New York Academy of Sciences, 1191
J. Abutalebi, P. Rosa, D. Green, M. Hernández, P. Scifo, Roland Keim, S. Cappa, Albert Costa (2012)
Bilingualism tunes the anterior cingulate cortex for conflict monitoring.
Cerebral cortex, 22 9
F. Huettig, Joost Rommers, A. Meyer (2011)
Using the visual world paradigm to study language processing: a review and critical evaluation.
Acta psychologica, 137 2
T. Zhao, P. Kuhl, R. Zatorre (2018)
Linguistic effect on speech perception observed at the brainstem
Proceedings of the National Academy of Sciences of the United States of America, 115
Naja Ramírez, Rey Ramírez, Maggie Clarke, S. Taulu, P. Kuhl (2017)
Speech discrimination in 11-month-old bilingual and monolingual infants: a magnetoencephalography study.
Developmental science, 20 1
C. Papagno, T. Valentine, A. Baddeley (1991)
Phonological short-term memory and foreign-language vocabulary learning☆
Journal of Memory and Language, 30
Tianlin Wang, J. Saffran (2014)
Statistical learning of a tonal language: the influence of bilingualism and previous linguistic experience
Frontiers in Psychology, 5
Andrea Weber, A. Cutler (2004)
Lexical competition in non-native spoken-word recognition
Journal of Memory and Language, 50
L. García-Pentón, Alejandro Fernández, Y. Iturria-medina, Margaret Gillon-Dowens, M. Carreiras (2014)
Anatomical connectivity changes in the bilingual brain
NeuroImage, 84
J. Abutalebi, Lucia Guidi, V. Borsa, M. Canini, P. Rosa, Ben Parris, B. Weekes (2015)
Bilingualism provides a neural reserve for aging populations
Neuropsychologia, 69
K. Waldie, Gjurgjica Badzakova-Trajkov, Branka Miliivojevic, I. Kirk (2009)
Neural activity during Stroop colour-word task performance in late proficient bilinguals: a functional magnetic resonance imaging study
Psychology and Neuroscience, 2
J. Gurd, Nicola Bessell, R. Bladon, J. Bamford, J. Bamford (1988)
A case of foreign accent syndrome, with follow-up clinical, Neuropsychological and phonetic descriptions
Neuropsychologia, 26
Michael Anderson, C. Green (2001)
Suppressing unwanted memories by executive control
Nature, 410
Sarah Grey, C. Sanz, K. Morgan‐Short, M. Ullman (2017)
Bilingual and monolingual adults learning an additional language: ERPs reveal differences in syntactic processing
Bilingualism: Language and Cognition, 21
Arturo Hernandez, M. Dapretto, J. Mazziotta, S. Bookheimer (2000)
Language Switching and Language Representation in Spanish–English Bilinguals: An fMRI Study
NeuroImage, 14
Yanping Dong, Fei Zhong (2017)
Interpreting experience enhances early attentional processing, conflict monitoring and interference suppression along the time course of processing
Neuropsychologia, 95
E. Bialystok, F. Craik, G. Luk (2012)
Bilingualism: consequences for mind and brain
Trends in Cognitive Sciences, 16
D Klein, RJ Zatorre, B Milner, E Meyer, AC Evans (1994)
Left putaminal activation when speaking a second language
Neuroreport., 5
V. Douet, Linda Chang (2015)
Fornix as an imaging marker for episodic memory deficits in healthy aging and in various neurological disorders
Frontiers in Aging Neuroscience, 6
A. Maggu, Wenqing Zong, V. Law, P. Wong (2018)
Learning Two Tone Languages Enhances the Brainstem Encoding of Lexical Tones
Michael Cole, Jeremy Reynolds, Jonathan Power, G. Repovš, A. Anticevic, T. Braver (2013)
Multi-task connectivity reveals flexible hubs for adaptive task control
Nature neuroscience, 16
Ananthanarayan Krishnan, Yisheng Xu, J. Gandour, P. Cariani (2005)
Encoding of pitch in the human brainstem is sensitive to language experience.
Brain research. Cognitive brain research, 25 1
E. Coderre, Walter HEUVEN (2014)
Electrophysiological Explorations of the Bilingual Advantage: Evidence from a Stroop Task
PLoS ONE, 9
Laura Spinu, Jiwon Hwang, Renata Lohmann (2018)
Is there a bilingual advantage in phonetic and phonological acquisition? The initial learning of word-final coronal stop realization in a novel accent of English
International Journal of Bilingualism, 22
M. Tremblay, Laura Sabourin (2012)
Comparing behavioral discrimination and learning abilities in monolinguals, bilinguals and multilinguals.
The Journal of the Acoustical Society of America, 132 5
Viorica Marian, Michael Spivey (2003)
Bilingual and monolingual processing of competing lexical items
Applied Psycholinguistics, 24
C. Pliatsikas, V. Deluca, Elisavet Moschopoulou, J. Saddy (2016)
Immersive bilingualism reshapes the core of the brain
Brain Structure & Function, 222
J. Kuipers, G. Thierry (2012)
Event-related potential correlates of language change detection in bilingual toddlers
Developmental Cognitive Neuroscience, 2
M. Stein, A. Federspiel, T. Koenig, M. Wirth, W. Strik, R. Wiest, D. Brandeis, T. Dierks (2012)
Structural plasticity in the language system related to increased second language proficiency
Cortex, 48
Andrea Stocco, C. Lebiere, John Anderson (2010)
Conditional routing of information to the cortex: a model of the basal ganglia's role in cognitive coordination.
Psychological review, 117 2

Publisher: Springer Journals
Copyright: Copyright © 2019 by The Author(s)
Subject: Biomedicine; Neurosciences; Neurology; Behavioral Therapy; Psychiatry
eISSN: 1744-9081
DOI: 10.1186/s12993-019-0157-z
Publisher site: See Article on Publisher Site

Abstract

Language has the power to shape cognition, behavior, and even the form and function of the brain. Technological and scientific developments have recently yielded an increasingly diverse set of tools with which to study the way language changes neural structures and processes. Here, we review research investigating the consequences of mul- tilingualism as revealed by brain imaging. A key feature of multilingual cognition is that two or more languages can become activated at the same time, requiring mechanisms to control interference. Consequently, extensive experi- ence managing multiple languages can influence cognitive processes as well as their neural correlates. We begin with a brief discussion of how bilinguals activate language, and of the brain regions implicated in resolving language conflict. We then review evidence for the pervasive impact of bilingual experience on the function and structure of neural networks that support linguistic and non-linguistic cognitive control, speech processing and production, and language learning. We conclude that even seemingly distinct effects of language on cognitive operations likely arise from interdependent functions, and that future work directly exploring the interactions between multiple levels of processing could offer a more comprehensive view of how language molds the mind. Keywords: Bilingualism, Multilingualism, Neuroplasticity, Experience-dependent plasticity, Language experience, Cognitive function, Executive control, Language learning, Speech processing cortex after just 7 days of learning to juggle [5]. Here, we Background discuss the neurofunctional and neurostructural con There are nomadic children off the coast of Thailand - who can “see like dolphins” [1]. These sea nomads of the sequences of a different type of juggling—namely, the Moken tribe spend considerable time diving for food, experience of juggling multiple languages within a single and have consequently learned to adjust their pupils to cognitive system. improve their vision underwater [2]. Such differences Language processing ranks among the most ubiqui- among people of different backgrounds and expertise tous, yet cognitively complex tasks that we engage in on a illustrate the powerful influence that experience can have daily basis. But unlike the effort put into activities such as on the function and physiology of our bodies. What may practicing the piano or training for a marathon, the per- be more surprising is that experience can change the vasiveness of language in almost every facet of our lives brain. There is now substantial evidence of neuroplastic makes it easy to overlook as a form of intense exercise. changes associated with expertise, ranging from enlarged This is especially the case for bilinguals, who may appear hippocampi among London taxi drivers [3] to greater to function effortlessly in a single language, while cov - volume in insular subregions of expert action video ertly managing multiple linguistic systems that may be game players [4]. Even brief periods of training have been competing with each other for activation. Early models shown to elicit structural changes, such as in the case of of bilingual cognition posited that one language could be increased gray matter density in the occipito-temporal independently activated without the other, either through a single “language switch” mechanism (i.e., Penfield and Roberts’ “one switch” model [6]), or through independ- *Correspondence: v-marian@northwestern.edu ent switches for output (controlled by the speaker) and Department of Communication Sciences and Disorders, Northwestern input (controlled by the environment) (i.e., Macnamara’s University, 2240 Campus Drive, Evanston, IL 60208, USA © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat iveco mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creat iveco mmons .org/ publi cdoma in/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 2 of 24 “two switch” model [7]). Since then, research has led to the basal ganglia and their constituent regions includ- a more integrated view of bilingual cognition, although ing the putamen and caudate nucleus, which are associ- the strength of activation for each language can indeed ated with functions involved in procedural memory, skill be selectively influenced by both top-down (e.g., expec - learning, planning, and coordination [38, 40–42]. The tations [8, 9]) and bottom-up inputs (e.g., language-spe- repeated engagement of these neural networks to man- cific acoustic cues [10, 11]). In fact, research utilizing age language conflict has both functional and structural numerous techniques ranging from eye-tracking [12– consequences. In some cases, bilingual experience affects 20] to electroencephalography (EEG) [21–26] has pro- neural activity in the absence of behavioral changes, vided ample evidence that multiple languages can be, while in others, it has been associated with a number and often are, activated in parallel. Using eye-tracking of language-specific and domain-general advantages and the visual world paradigm [27, 28], Spivey and Mar- relative to monolinguals. In the following sections, we ian [12] observed that when Russian-English bilinguals review some examples of how bilingual experience can were asked to pick up a particular object from an array, affect both the function and structure of neural regions they made eye movements towards other objects with underlying different components of language processing. phonologically similar labels. Critically, bilinguals fix - Given that managing language conflict is among the most ated on both within- and between-language competi- essential functions for bilingual language processing, tors, such that an instruction to pick up the “marker” we begin with neuroplastic changes to networks associ- in English would elicit eye movements towards a stamp ated with linguistic and non-linguistic cognitive control. (“marka” in Russian). This demonstrates that bilinguals We then provide evidence that bilingual experience can may consider lexical candidates from both languages influence some of the earliest stages of language process - during speech comprehension. Utilizing EEG, Thierry ing by altering how people encode and attend to sounds, and Wu [26] observed that when Chinese-English bilin- resulting in behavioral consequences for speech percep- guals were asked to judge the semantic relatedness of two tion and production. Lastly, we consider how changes to words in English, their brain potentials indicated activa- both high-level executive functions and low-level percep- tion of their Chinese translations. Specifically, there was tion can impact the ability to learn additional languages a reduction in the N400 component (an index of seman- (e.g., L3, L4, …) (see Fig. 1 for a visual schematic of the tic integration) both when participants judged words that processes and neural regions affected by bilingual experi - were related in the target language (English), as well as ence). We broadly organize our discussions around these those that shared a character in the non-target language three topics, not to describe distinct phenomena, but (Chinese). Evidence of co-activation has been observed rather to illustrate the ways in which seemingly disparate across phonological [12], orthographic [29], lexical [21], consequences of bilingual experience may be intertwined and morphosyntactic [30] levels of representation, which through overlapping networks and functions. We there- raises the question of how bilinguals are able to operate fore conclude by stressing the importance of examining in a single-language mode without intrusions from the the relationships among the various effects of bilingual unintended language. experience on the brain in order to fully appreciate the The precise mechanisms that allow for the successful widespread and interconnected consequences of living as control of multiple languages have yet to be definitely a multilingual. established. Some have posited that the non-target lan- guage is inhibited, others that the target language is facil- Linguistic and non‑linguistic cognitive control itated, yet others that the target language is selected (see Functional brain activity [31] for a review). Models such as Green and Abutalebi’s A key feature of bilingual cognition is the parallel acti- Adaptive Control Hypothesis [32] posit a more complex vation of multiple languages, and the subsequent need system that includes various functions such as monitor- to prevent interference from the non-target language. ing, inhibition, task engagement and disengagement, Because language interference appears to be managed which are employed to varying degrees depending on using similar neural networks recruited for general cog- the context. It has also been suggested that bilingual nitive control, there may be a bilingual advantage for language control may recruit many of the same neural tasks that require ignoring irrelevant information (see regions utilized for domain-general cognitive control [43] for review). Such behavioral differences are most [33, 34]. These include the prefrontal cortex, which is readily observed in children and older adults, while the associated with goal maintenance and conflict resolution bilingual advantage appears to be less robust for young [34–36], the anterior cingulate cortex and neighboring adults who generally have a higher capacity for cogni- pre-supplementary motor area, associated with con- tive control [44]. Yet, even when no behavioral differ - flict-monitoring and attention regulation [37–39], and ences are observed, there is evidence that bilinguals may Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 3 of 24 Fig. 1 Multilingual experience has widespread consequences for functions ranging from cognitive control to speech processing to language learning. Practice juggling multiple languages leads to functional and structural changes to the brain, such as to the prefrontal cortex (PFC), anterior cingulate cortex (ACC), caudate nucleus (CN), cerebellum, brainstem, Heschel’s gyrus (HG), putamen, superior temporal gyrus (STG), inferior frontal gyrus (IFG), anterior temporal lobe (ATL), and supramarginal gyrus (SMG) in the inferior parietal cortex (IPC) be utilizing more efficient control processes. Marian greater activation in any regions when resolving within- et al. [45] investigated the neural correlates of linguistic language competition relative to the control condition. control during lexical competition using fMRI and the The frequent practice managing competition not only visual world paradigm described earlier. When monolin- within, but also between languages may make bilinguals guals were asked to select a target among a display that more efficient at resolving linguistic conflicts, leading included a phonologically similar competitor, there was to less reliance on networks associated with cognitive significant activation of executive control regions such control. as the anterior cingulate cortex (ACC) and the superior Evidence of more efficient processing has been found temporal gyrus (STG) relative to trials without a com- during non-linguistic tasks as well. Both Abutalebi petitor. Critically, bilinguals did not have significantly et al. [46] and Garbin et al. [47] observed that bilinguals Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 4 of 24 not only outperformed monolinguals during a non-lin- Potentially in line with the latter hypothesis, Kousaie guistic executive control task, but also had less activity and Phillips observed group differences even for trials in the ACC, consistent with Marian et al.’s [45] find - without conflicting stimuli (i.e., congruent trials), indi - ings. Bilingual experience can additionally influence the cating that bilingualism may confer a global processing functional connectivity between different brain areas. advantage (often referred to as the bilingual executive Becker et al. [48] collected fMRI data from bilinguals processing advantage, or BEPA [60]). Coderre and van and monolinguals as they completed a task requiring Heuven [61] similarly observed that bilinguals had both the application of continuously changing rules. Using faster reaction times and reduced conflict-related ERP Dynamic Causal Modeling, the authors constructed amplitudes compared to monolinguals during non- three models depicting the connectivity of three areas linguistic, non-conflict trials of a modified Stroop task. known to be associated with cognitive flexibility (ACC, Group differences in ERP amplitude were even observed striatum, and dorsolateral prefrontal cortex, or DLPFC) before the potentially conflicting target stimulus was and compared them to the obtained neural data. They presented, suggesting that bilinguals may be engaging in observed that for both bilinguals and monolinguals, the more proactive management of incoming information in ACC was the driving force, influencing activity in the the absence of a conflict. However, there is also evidence striatum and DLPFC to accomplish tasks involving cog- indicative of greater neural efficiency more specific to nitive flexibility. However, while increased ACC activity active inhibitory control (often described as the bilingual resulted in a modest increase in DLPFC and striatum inhibitory control advantage, or BICA [60]). Heidlmayr activity for bilinguals, greater ACC activity prompted et al. [62] found that bilinguals using their L2 showed a significant decreases in activity in both regions for smaller N400 conflict effect during a Stroop task (i.e., the monolinguals. The relatively mild influence of the ACC difference between incongruent and congruent trials) on other regions for bilinguals may be interpreted as compared to monolinguals. Using a flanker task, Dong a reduced response to conflict, potentially consistent and Zhong [49] observed ERP activity consistent with with Abutalebi et al.’s [46] finding. In one case, ACC both BEPA and BICA. Relative to bilingual interpret- activity is directly modulated, while in the other, the ers with less interpreting experience, those with greater influence of ACC on other neural structures is reduced. experience showed a global processing advantage for Studies utilizing EEG have yielded additional evidence conflict monitoring, as indexed by the earlier N2 com - that may be indicative of greater neural efficiency among ponent (i.e., both congruent and incongruent trials), and bilinguals [49–52], though with somewhat variable find - more efficient inhibitory control for the later P3 compo - ings depending on the population and task. One com- nent (i.e., a smaller conflict effect). monly examined ERP measure is the N2 component, Differences in neural efficiency are primarily attributed which is thought to index conflict monitoring [53] or to experience managing linguistic interference, as men- inhibition [54]. The N2 is typically larger when there is a tioned earlier. However, the need to resolve lexical com- conflict (e.g., incongruent trials of a Simon task) [55], and petition is not exclusive to bilinguals, as selecting words is correlated with ACC activity [56]. A number of studies within a language also requires the inhibition of semanti- have revealed larger N2 amplitudes for bilinguals on con- cally and phonologically similar competitors. So why is it flict trials during Go/No-Go [57, 58] and AX-CPT tasks that practice resolving lexical conflicts appears to have a [52], leading some researchers to conjecture that bilin- more significant impact on domain-general processes for guals may be engaging in greater conflict monitoring or bilinguals than monolinguals? Part of the reason is likely inhibition. On the other hand, Kousaie and Phillips [51, due to the fact that bilinguals experience competition 59] observed that bilinguals elicited smaller [51] and ear- both within and across languages. However, another rea- lier [59] N2s during a Stroop task compared to monolin- son may be because bilinguals utilize more overlapping guals. While the smaller N2 amplitude among bilinguals networks for language processing and domain-general differs from the aforementioned findings, it is consistent cognitive control relative to monolinguals [47, 63–65]. In with the results from fMRI studies observing less bilin- one study by Coderre et al. [64], neural activity was meas- gual activation of the ACC, which may reflect a reduced ured while participants completed semantic tasks involv- need for active conflict monitoring (despite equivalent ing non-linguistic competition, linguistic competition, or [51] or even superior [59] performance). It may therefore language processing without competition. The authors be the case that depending on the task and population, observed that while bilinguals recruited similar neural bilinguals either engage in greater inhibition/monitoring regions for all three tasks (e.g., the left inferior frontal (resulting in larger N2s), or else more efficient general gyrus; L IFG), monolinguals utilized different regions processing, thereby reducing the need for active moni- depending on the task. As such, not only do bilinguals toring (resulting in smaller N2s). have more practice managing linguistic conflict relative Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 5 of 24 to monolinguals, but the impact of such practice on gen- experience can result in greater and more flexible coordi - eral cognitive control is likely greater as well. nation of different neural regions and networks. While the exact nature of the mechanisms underlying Next, we review evidence that the effects of bilingual greater efficiency are still under investigation, some mod - experience extend beyond functional changes in neuro- els such as the bilingual anterior to posterior and sub- logical activity to the actual structures that support them. cortical shift (BAPSS) model [66] posit that, over time, bilinguals may begin to recruit different regions to man - Structural brain matter age competition. Specifically, while bilinguals may rely Bilingual experience has been found to increase gray on the typical frontotemporal executive control regions matter density in regions implicated in executive control, during earlier stages, they may begin to recruit more including the DLPFC [75], left caudate nucleus (LCN; [40, automatic posterior perceptual/motor areas as they gain 76, 77]) and the ACC [78]. As noted previously, the pre- greater expertise. Data consistent with this hypothesis frontal cortex, and the DLPFC in particular, is believed to include the aforementioned findings that bilinguals rely play an important role for domain-general cognitive con- less on the ACC compared to monolinguals, as well as trol [79], as well as language control [35, 80]. Increased studies observing greater recruitment of perceptual and gray matter density in regions associated with cognitive motor regions such as the basal ganglia with bilingual control may partly account for the finding that bilingual - experience [67–69]. Luk et al. [70] provide converging ism can delay the onset of dementia [81, 82]. Consist- evidence by looking at resting-state functional connec- ent with this notion, Abutalebi et al. [78] observed that tivity (assessed by examining the correlations in brain while both monolinguals and bilinguals experienced age- activity between a chosen brain area, the IFG in this case, related gray matter reductions in the DLPFC, reduced and all other regions). The bilateral IFG were chosen as gray matter was only correlated with executive control the “seeds,” or sources of comparison, because bilinguals for monolinguals. In other words, while the groups had in their study had greater white matter integrity in these similar age-related effects at the anatomical level, there regions and because the IFG are known to be associated were greater negative consequences for monolinguals’ with both language and cognitive control [64]. While behavioral performance as a result of reduced gray mat- monolinguals had stronger associations between the ter. Though no structural differences of the DLPFC were seeds and other frontal regions, bilinguals had stronger found between the older bilinguals and monolinguals associations between the seeds and occipitoparietal in Abutalebi et al.’s study, Olulade et al. [75] did observe regions, supporting the idea that bilingualism may pro- greater gray matter volume among younger, Spanish– mote the use of more distributed networks involving English bilinguals compared to monolinguals. However, both frontal and perceptual/motor regions. no such increase was observed for English-ASL bimodal In addition to recruiting different networks, bilinguals bilinguals. The authors propose that because bimodal may have generally greater functional connectivity within bilinguals are able to utilize their two languages simulta- and across networks relevant to executive control. Grady neously, language conflict, and subsequent recruitment et al. [71] found that resting-state functional connec- of the DLPFC, is reduced. Interestingly, bimodal bilin- tivity was enhanced for bilinguals in the Default Mode gualism has been associated with increased gray matter Network (DMN; which includes the posterior cingulate, in the LCN, another region associated with language con- ventromedial prefrontal cortex, angular gyri and para- trol [40]. The authors observed that, among bilinguals, hippocampal gyri), and the frontoparietal control net- there was a positive correlation between gray matter den- work (FPC). Activity in the DMN is strongest during rest sity and LCN activation associated with language switch- and reduced during externally driven tasks [72]. Greater ing, providing further support for the involvement of the functional connectivity within the DMN has been shown LCN in bilingual language control. Greater gray mat- to promote deactivation during tasks, which in turn facil- ter density for bilinguals compared to monolinguals has itates performance [73]. Better executive control is thus additionally been found in the ACC [78], which is asso- predicted by the negative correlation between the DMN ciated with conflict monitoring [83, 84]. Abutalebi et al. and the FPC, the latter of which has highly flexible func - [46] observed a positive correlation between gray matter tional connectivity patterns and facilitates task-specific in the ACC and both behavioral and functional indices recruitment of neural regions [74]. In addition to greater of general cognitive control for bilinguals. Interestingly, functional connectivity within networks, Grady et al. no such relationship between gray matter density and observed that functional connectivity was more cor- functional activation/behavior was observed for mono- related across networks for bilinguals relative to mono- linguals. This latter result once again suggests that bilin - linguals. In other words, there is evidence that bilingual gualism can influence both the physical characteristics of Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 6 of 24 neuroanatomical structures, as well as the ways they are indirect measure of white matter integrity, in the cor- utilized. pus callosum (CC; see also [90, 91]), extending to bilat- Potentially related to the issue of processing efficiency, eral superior longitudinal fasciculi (SLF; see also [91]), a number of experiments have found a negative rela- and the right inferior fronto-occipital fasciculus (IFOF; tionship between gray matter in the LCN and language see also [91–93]). The CC is a thick tract connecting the exposure/expertise. DeLuca et al. [85] observed that LCN left and right hemispheres, and is associated with high- gray matter density of sequential bilinguals was reduced level cognitive processes such as executive function [94, after 3 years of immersion in an L2 context, and Pliatsi- 95]). The SLF is a long-range tract connecting the frontal kas et al. [86] observed differences in the LCN of mono - lobe to posterior parietal and temporal cortices, which linguals and bilinguals with less, but not more immersive along with the arcuate fasciculus (AF) is often classi- experience. Similarly, Elmer et al. [87] found that highly fied as the dorsal stream of the language network (espe - trained simultaneous interpreters had less gray matter cially implicated in speech perception and production volume in several language control regions compared to [96]). The IFOF connects frontal, occipital, and parietal multilingual non-interpreters, and that gray matter in the cortices, and has been proposed as the ventral stream of bilateral caudate nucleus was negatively correlated with language processing (associated with semantic process- the number of interpreting hours. At first glance, these ing [97]). Bilinguals with greater white matter integrity results seem at odds with the general observation that have also demonstrated greater functional connectivity gray matter increases with greater language competence between frontal and posterior cortical regions [70]. In (e.g., Hervais-Adelman et al. [76] who observed a positive other words, bilingual experience can facilitate more dis- relationship between gray matter in the caudate nucleus tributed functional connectivity, likely supported by the and a composite index of multilingual experience). How- integrity of white matter structures connecting the fron- ever, as speculated by Elmer et al. [87], reductions in tal lobe with more distant brain areas. gray matter may reflect cortical pruning associated with While a number of studies have reported greater white greater specialization and efficiency. In other words, gray matter integrity for bilinguals compared to monolinguals, matter density in particular regions (such as the LCN) particularly in the IFOF [91–93], there is also evidence of may initially increase as bilinguals gain greater mastery the opposite pattern [98–100]. For instance, Gold et al. over their languages, but then decrease as they become [99] observed that compared to age-matched monolin- more efficient at carrying out necessary functions (such guals, older bilinguals had less white matter integrity in as reducing interference from unwanted languages). This a number of tracts, including the IFOF, CC, and fornix greater efficiency could result from a number of differ - (which originates in the hippocampus and is associ- ent mechanisms, including increased specialization of ated with memory function [101]). Despite the apparent a particular region (such as the ACC as suggested by inconsistency with Luk et al’s findings [70], the authors Abutalebi et al. [46]) or else reliance on regions associ- point out that the bilinguals’ cognitive functioning did ated with different, potentially more procedural, func - not differ from monolinguals despite lower white mat - tions (consistent with the previously discussed BAPSS ter integrity. In fact, behavioral and fMRI data from the model [66]). For instance, DeLuca et al. [85] observed same subjects showed that the bilinguals were faster at that the same population of bilinguals who experienced task-switching despite less activation in frontal execu- a reduction in the LCN had significantly increased gray tive control regions [99]. The authors thus propose that matter volume in the cerebellum. Increased gray matter bilinguals may be efficiently compensating for reduced in the cerebellum has been associated with the ability to integrity in some tracts through the use of different path - control interference from a non-target language [88], as ways and neural regions (such as the relatively intact SLF well as grammatical processing in bilinguals [89]. DeLuca connecting frontal and subcortical areas in the executive et al. propose that their pattern of results may reflect a network). shift in neural networks as a result of more automated L2 Practice learning and managing multiple linguistic sys- processing. tems thus influences how individuals resolve conflict, in As noted previously, neuroimaging and electrophysio- some cases, leading to what appears to be more efficient logical evidence suggest that bilinguals may rely on more cognitive control. Table 1 provides a summary of stud- distributed networks compared to monolinguals [47, ies of language effects for tasks and regions relevant to 65]—a conclusion further supported by studies examin- linguistic and non-linguistic cognitive control. As can ing the integrity of white matter tracts connecting differ - be seen, bilinguals often have less activation of cortical ent areas of the brain. When comparing older bilingual regions traditionally associated with cognitive control and monolingual adults, Luk et al. [70] found that bilin- (such as the ACC and the PFC) when managing conflict. guals had higher fractional anisotropy (FA) values, an On the other hand, in addition to greater gray matter Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 7 of 24 Table 1 Consequences of bilingualism for linguistic and non‑linguistic cognitive control Type Region Effect Task Study ACC Functional ACC Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch for mono only) ACC Mono ≠ bi (greater activa- Visual world (phonological Marian et al. [45] tion for competitor than competition) control, mono only) ACC Mono > bi (activation Flanker Abutalebi et al. [46] associated with conflict effect) ACC Mono > bi (activation Stroop Waldie et al. [69] associated with conflict effect) Structural ACC Mono ≠ bi (− correlation: Flanker Abutalebi et al. [46] gray matter/conflict effect, bi only) ACC Bi > mono (gray matter) Flanker Abutalebi et al. [78, 179] ACC Multilingual con- Elmer et al. [87] trols > interpreters (gray matter); controls ≠ inter- preters (− correlation: gray matter/interpreting hours; interpreters only) Frontal cortex/gyrus Functional L IFG Mono ≠ bi (overlapping Linguistic/non-linguistic Coderre et al. [64] activation across tasks, flanker; semantic cat - bi only) egorization L IFG Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non-switch, bi only) R IFG Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch, mono only) SFG Mono ≠ bi (greater activa- Visual world (phonological Marian et al. [45] tion for competitor than competition) control, mono only) SFG, MFG, IFG Mono > bi (activation Stroop Waldie et al. [69] associated with conflict effect) R SFG/R MFG Between > within- Visual world (phonological Marian et al. [67] language (activation competition) associated with conflict effect) R SFG/R MFG/R IFG Dominant > non-dominant Visual world (phonological Marian et al. [67] language competition competition) (activation associated with conflict effect) Structural DLPFC Mono ≠ bi (− correlation: Flanker Abutalebi et al. [78, 179] gray matter/conflict effect, mono only) SFG Bi > mono (gray matter) Language switching Zou et al. [40] MFG, IFG, R SFG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) IFG Multilingual con- Elmer et al. [87] trols > interpreters (gray matter); controls ≠ inter- preters (− correlation: gray matter/interpreting hours; interpreters only) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 8 of 24 Table 1 (continued) Type Region Effect Task Study Temporal cortex/gyrus Functional MTG, STS Visual world (phonological Marian et al. [45] Mono ≠ bi (greater activa- competition) tion for competitor than control, mono only) Structural R MTG, R ITG, Mono > bi (gray matter) Olulade et al. [75] (experi- ment 1) R STG, L MTG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) L ITG Bi > mono (gray matter) Language switching Zou et al. [40] Parietal cortex/gyrus Functional L IPL Mono ≠ bi (greater activa- Non-verbal task switching Garbin et al. [47] tion for switch than non- switch for mono only) Structural R IPL Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) L SMG Multilingual con- Elmer et al. [87] trols > interpreters (gray matter) Occipital cortex/gyrus Functional Bi > mono (EEG complex- Non-verbal task switching Grundy et al. [66, 68] ity); mono ≠ bi (− cor- relation: complexity/ conflict effect, bi only) Structural L SOG, L IOG Bi > mono (gray matter) Olulade et al. [75] (experi- ment 1) Subcortical Functional L CN Bi > mono (activation Stroop Waldie et al. [69] associated with conflict effect) L CN Bi only: more LCN activa- Language switching Zou et al. [40] tion when language switching than when not L CN/L putamen Bi only : between > within- Visual world (phonological Marian et al. [67] language (activation competition) associated with conflict effect) Structural L CN Bi > mono (gray matter) Language switching Zou et al. [40] L CN More > less multilingual Hervais-Adelman et al. [76] experience (gray matter) Striatum Non-verbal task switching Garbin et al. [47] Mono ≠ bi (+ correla- tion: gray matter/faster switching, bi only) CN Controls ≠ interpreters Elmer et al. [87] (− correlation: gray mat- ter/interpreting hours; interpreters only) L CN/Hip/Amg Less > more immersion Deluca et al. [85] (gray matter contraction) L Cb More > less immersion Deluca et al. [85] (gray matter) Cb Mono > bi (gray matter) Olulade et al. [75] (experi- ment 1) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 9 of 24 Table 1 (continued) Type Region Effect Task Study Multiple/other Functional ACC, PFC, striatum Rapid instructed task Becker et al. [48] Bi ≠ mono (− correlation: learning ACC/PFC and striatum for monos; + correlation: ACC/PFC and striatum for bis) e.g., ACC, PFC, CN, puta- Bi > mono (overlapping Verbal/non-verbal switch- Anderson et al. [63] men activation across tasks) ing Bi > mono (overlapping Verbal/non-verbal task Timmer et al. [65] activation across tasks) switching Bi < mono (amplitude of Stroop, Simon, and Eriksen Kousaie and Phillips [51] N2 in Stroop), mono > bi tasks (amplitude of P3 in Simon), bi ≠ mono (longer delay in P3 latency in Eriksen in monos) Bi < mono (N positivity Stroop Coderre and van Heuven Inc post-target onset) [61] Bi > mono (N negativity Inc pre-target onset) Bi < mono (N400 conflict Stroop/negative priming Heidlmayr et al. [62] effect for Stroop) Bi > mono (CRN and ERN LANT Kałamała et al. [50] negativity) More > less interpreting Flanker Dong and Zhong [49] experience (N1/N2 amplitude); less > more interpreting experience (P3 amplitude for incon- gruent trials only) Bi > mono (N2 on NoGo) Go/NoGo Fernandez et al. [57] Bi > mono (N2 and late Go/NoGo Moreno et al. [58] positivity wave on NoGo) Bi > mono (N2 and P3 to AX-CPT Morales et al. [52] AY ) DMN, FPC Bi > mono (resting-state Grady et al. [71] connectivity within and between networks) Frontal, occipital, parietal Bi > mono (frontal-occip- Luk et al. [70] regions itopartietal resting-state connectivity) Bi < mono (frontal resting- state connectivity) Structural SLF, IFOF Bi > mono (white matter) Luk et al. [70] ILF/IFOF, fornix, CC Mono > bi (white matter) Gold et al. [99] volume in these same frontal regions, bilinguals often Summary of functional and structural effects of bilin - have stronger activation of control-relevant subcortical gual experience for tasks and neural regions associated areas (e.g., LCN), which is likely facilitated by more wide- with linguistic and non-linguistic cognitive control. spread and flexible functional and structural connectiv - Given the pervasive involvement of cognitive control in ity. These patterns reflect two possible ways in which a wide variety of tasks (e.g., [102–104]), an effect of bilin - bilingual experience may support executive function—by gualism on this central function could initiate a chain of enhancing the robustness of the underlying neural struc- consequences across multiple domains and stages of pro- tures, as well as by potentially recruiting more efficient cessing. We illustrate the potentially vast impact of bilin- networks to accomplish the same cognitive control task. gual effects on the brain by considering one of the earliest Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 10 of 24 stages of language processing: the perception and pro- than a dozen languages [115]. Moreover, despite the fact duction of speech sounds. that monolingual speakers of tone languages such as Cantonese and Mandarin have been shown to have highly Speech perception and production robust brainstem responses [117, 120], bilingual speak- Functional brain activity ers of two tone languages exhibit even stronger encoding Studies utilizing EEG have provided evidence that bilin- [114]. This additive effect of language experience aligns gual experience can enhance attention to speech stimuli with the finding that the consistency and strength of f0 [105–107]. For instance, both bilingual toddlers and encoding among children is positively associated with the bilingual adults are quicker than monolinguals at detect- amount of bilingual experience [112]. ing language switches [105, 106]. Further evidence comes A recent study by Zhao and Kuhl [121] confirmed the from a study in which children were presented with pic- link between brainstem encoding and conscious speech tures followed by words that were either related or unre- perception. Building on the well-established finding that lated. While ERPs did not vary between language groups the perception of speech sounds varies as a function of at later stages of semantic processing, only bilinguals had native language background (e.g., sensitivity to phone- ERPs indicating attention to unexpected phonemes dur- mic contrasts of the native language [122]), the authors ing early stages [107]. In addition to earlier responses to observed that differences in how sounds were perceived speech stimuli, Chinese–English bilinguals have been correlated with different patterns of encoding at the found to attend more globally to entire words as com- brainstem. It is possible that more robust and consistent pared to English monolinguals who focus the most on encoding among bilinguals could additionally facilitate word onsets, as indexed by the relative amplitude of the discrimination of non-native contrasts, as has been found N1 component, which is associated with attention [108]. for individuals with musical expertise [123]. Early in The authors suggest that because the segments of words development, infants are sensitive to phonetic contrasts that are most critical for word identification may vary of all languages, but eventually become tuned to their across different languages, it may be more efficient to dis - native language. However, it has been suggested that tribute attention across all segments rather than switch bilingual experience may prolong the period of universal strategies depending on which language is being used. discriminability (i.e., “the perceptual wedge hypothesis”). In other words, bilingual experience leads to changes in Petitto et al. [124] found that while 10 to 12-month-old both the time course and distribution of attentional allo- monolingual infants were no longer sensitive to non- cation, and has been found to enhance attentional con- native contrasts, activity in the LIFC indicated that bilin- trol when processing non-speech stimuli as well (e.g., gual infants were sensitive to phonetic contrasts of both tones [109]). native and non-native languages. Findings from a recent Enhanced attentional control among bilinguals has MEG study additionally suggest that 10 to 12-month- even been associated with changes to how robustly old bilinguals may analyze speech sounds based on speech sounds are encoded at the level of the brainstem acoustic (as opposed to phonetic) properties to a greater [110–115]. Auditory brainstem responses (ABR) are a extent than monolinguals [125]. This prolonged period measure of encoding strength, and encoding of the fun- of acoustic analysis may be adaptive for dealing with the damental frequency (f0) in particular has been found to increased variability associated with multiple phonemic be both experience-dependent [116, 117] and predictive systems and may help bilinguals retain the ability to dis- of speech perception ability [118, 119]. Krizman et al. criminate non-native contrasts. Indeed, bilingual infants [111] observed that encoding of the f0 was more robust as old as 18–20 months were found to be sensitive to the for bilinguals than monolinguals when listening to speech phonemic contrasts of a novel language (Ndebele clicks), stimuli such as/da/, and that this enhancement was corre- while monolinguals were not [126]. lated with attentional control. This finding highlights the While enhanced bilingual discrimination of non-native potential interconnectivity of bilingual effects on execu - contrasts does not appear to persist into adulthood at tive function and speech-sound processing. Furthermore, initial exposure [127, 128], there is evidence suggesting the relationship between the consistency of ABRs and that bilinguals may be better at learning non-native con- attentional control has been found to be stronger among trasts relative to monolinguals after training [127, 129, bilinguals compared to monolinguals, likely as a result of 130]. In addition to better discrimination of non-native the greater demands associated with communicating in contrasts during comprehension, bilingualism may con- multiple languages [110]. Recent work has revealed that fer advantages for the production of novel sounds. For the effect of bilingualism on neural encoding is remark - example, Spinu et al. [131] recently found that after train- ably consistent, with similar effects regardless of socio - ing, bilinguals were better able to reproduce a non-native economic status [113], and for bilingual speakers of more Sussex English accent (as measured by the glottal-stop Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 11 of 24 rate) compared to monolinguals. The authors conjecture foreign accents were associated with a reduction in the that this bilingual advantage for phonological acquisition surface area of the STG and MFG [142], though balanced may be related to their more robust encoding of speech bilingual children had relatively less cortical thickness in sounds at the level of the brainstem. Specifically, they these regions. Rodriguez et al. [143] similarly found that propose that stronger subcortical encoding of sounds cortical thickness of the anterior insula was negatively may translate to richer acoustic signals in auditory sen- correlated with the ability to learn foreign phonological sory memory, eventually leading to more efficient pro - contrasts among bilinguals. These latter results may orig - cessing of speech. inate from similar processes as the previously-discussed As with executive control, speech perception and reduction in gray matter volume for expert interpreters production are influenced not only by the efficiency [87]. Specifically, it may be the case that initial training of particular neural regions, but also by the functional enhances cortical volume/thickness while greater exper- connectivity across brain areas. For instance, Ventura- tise and efficiency will eventually lead to cortical pruning. Campos et al. [132] discovered that resting-state func- Consistent with this notion, Elmer et al. [144] found that tional connectivity between inferior frontal (left frontal interpreters had significantly reduced white matter rela - operculum/anterior insula) and parietal regions (left tive to controls in regions associated with sensory-motor superior parietal lobule) predicted how well individu- coupling and speech articulation (e.g., L anterior insula, als were able to learn non-native contrasts after train- R IPL, and upper cortico-spinal tract), as well as with ing. As noted previously, bilingualism has been shown to executive function (e.g., R CN, CC). enhance resting-state functional connectivity in the fron- One region that has been found to be larger for bal- tal–parietal network [71]. Additionally, it has been found anced bilingual children is the putamen [142], consist- that early bilinguals have greater functional connectivity ent with a number of other studies finding greater gray in language networks relevant to phonological process- matter density in this region for bilinguals compared to ing (as well as semantic processing) relative to late bilin- monolinguals [41, 86, 145]. The putamen has been impli - guals with comparable proficiency [133]. Berken et al. cated in language production and articulation [146, 147], [134] similarly observed that early bilinguals had greater dramatically evinced by the fact that lesions to the area connectivity between the IFG and a number of language can disrupt a speaker’s ability to produce phonemes of processing and executive control regions including the their native language, resulting in speech that appears cerebellum, which is associated with processes underly- to be foreign accented (i.e., Foreign-Accent Syndrome ing speech perception and production [135], as well as [148]). Greater gray matter density in the putamen of language control [88]. bilinguals compared to monolinguals is likely to result from the more complex articulatory repertoire associated Structural brain matter with learning and utilizing multiple languages. Among Bilingual experience has been associated with struc- bilinguals, lower proficiency has been associated with tural changes to brain regions supporting both auditory greater putamen activity, possibly reflecting increased processing and speech production. Ressel et al. [136] articulatory effort [41, 146, 149]. Additionally, Berken observed a relationship between early bilingual experi- et al. [150] observed that among sequential bilinguals, ence and increased gray and white matter volumes in there was a positive correlation between more native-like Heschel’s gyrus (HG), a part of the temporal lobe that accents and gray matter density in the left putamen (as contains the primary auditory cortex. Faster [137] and well as a number of other regions implicated in speech- more successful [138] identification of foreign speech motor control). Together, these findings may suggest that sounds has been linked to greater white and gray matter gray matter density in the left putamen underlies native- volumes, respectively. Enhanced volume in this region like articulation ability, and that speakers experiencing among bilinguals thus coincides with the aforemen- difficulty may compensate by activating this region to a tioned advantages for learning non-native phonemic con- greater degree (potentially inducing structural changes as trasts [127, 129, 130]. Mårtensson et al. [139] observed they improve). that compared to controls, bilingual interpreters had Lastly, and as noted previously in our discussion of increased cortical thickness in the superior temporal cognitive control, bilingual experience has been shown gyrus (STG), a region consistently activated during acous- to enhance white matter integrity in the SLF [70, 77, 91], tic–phonetic processing [140]. The authors additionally as well as the IFOF [91–93], representing the dorsal and found greater cortical thickness among interpreters in ventral streams of language processing, respectively. The the middle frontal gyrus (MFG), part of the articulatory SLF, and the AF in particular, are associated with phono- network that contributes to pronunciation aptitude [141]. logical processing and articulation [151]. Among bilin- A recent study with bilingual children found that stronger guals, a number of variables have been shown to affect Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 12 of 24 white matter integrity in the SLF/AF. Higher proficiency at native language competitors relative to bilinguals. [152] and greater immersive L2 experience [100, 153] are In addition to vocabulary acquisition, there is evidence predictive of enhanced structural integrity, while find - that bilingualism may facilitate learning of novel syntax ings for age of L2 acquisition are mixed [152, 154]. While [162, 163], though the findings are somewhat mixed. In Nichols and Joannis [152] found a positive association a recent EEG study, Grey et al. [164] observed no behav- between age of acquisition and white matter in the AF, ioral difference between bilinguals and monolinguals Hämäläinen et al. [154] observed greater white matter for learning an artificial language. However, there were dis - early compared to late bilinguals. tinct ERP patterns associated with their grammatical- Table 2 summarizes recent research on the functional ity judgments. At high proficiency, both monolinguals and structural effects of multilingual experience on oper - and bilinguals showed native-like ERPs (a P600 compo- ations and brain regions relevant to speech perception nent associated with syntactic processing), whereas at and production. There is reliable evidence that bilingual low proficiency, only bilinguals showed this pattern. In experience can enhance attention to speech stimuli and other words, even when no behavioral differences are result in more consistent and robust encoding of sound observed, bilinguals show more native-like processing at in the brainstem, suggesting that bilingual experience has early stages of acquiring a novel language. The authors (often beneficial) effects on the neural functions under - suggest that enhanced cognitive control could once again lying both cognitive control and speech processing. Fur- play a role, as bilinguals may be better able to reduce thermore, the consequences of bilingual experience on interference from the syntax of known languages. As speech processing may partly originate from changes to noted previously, this greater efficiency may be achieved cognitive control. Bilingualism has also been found to through the recruitment of different neural networks to affect the structure of regions underlying both functions, control interference from a non-target language. Evi- though in some cases, it is not yet clear how specific ana - dence of such a process during language learning comes tomical characteristics align with behavioral expertise from Bradley, King, and Hernandez [165] who found and outcomes. In the final section, we extend the poten - that after just 2 h of exposure to a new language, bilin- tial “chain of bilingual consequences” one step further by guals were not only faster at making semantic judgments exploring how enhanced cognitive control and speech in response to novel words compared to monolinguals, processing may translate to a greater capacity for learn- but also recruited different neural networks. Specifically, ing new languages. monolinguals relied more on regions typically associated Summary of functional and structural effects of bilin - with executive control such as the DLPFC, ACC, SMA, gual experience for tasks and neural regions associated and LCN, while bilinguals only showed increased activa- with speech perception and production. tion in the putamen. Given that the putamen is associated with phonologi- Language learning cal processing and articulation [166, 167], the bilingual Functional brain activity advantages for language learning may be connected to the Evidence suggests that bilingual experience may con- effects of language experience on speech processing, in fer benefits for learning new languages beyond the two addition to cognitive control. Consistent with this notion, that are already known, in part, as a result of changes Kaushanskaya and Marian [157] found that bilinguals to executive function [155–160] (see [161] for review). outperformed monolinguals when learning novel words, For example, Kaushanskaya and Marian [159] observed and that better performance was correlated with phono- that bilinguals were better able to learn novel words logical working memory among early bilinguals, but not that had letter-to-sound mappings that diverged from late bilinguals or monolinguals. This was despite the fact those of their known languages. Participants were asked that phonological working memory has been previously to recall words after hearing a novel word from an arti- linked to word learning for monolinguals [168, 169]. The ficial language either with or without its written form. authors propose that because the novel words were pho- In cases where participants read a word with orthogra- nologically dissimilar to the native language (English), phy that conflicted with letter-to-sound mappings of monolinguals and late bilinguals may not have been able known languages, bilinguals were significantly better at to efficiently utilize their phonological working memory inhibiting interference from letter-to-sound mappings to learn them. Early bilinguals, on the other hand, may be of their native tongue, thereby outperforming monolin- able to utilize phonological working memory resources guals. Similarly, Bartolotti and Marian [155] observed more efficiently to learn even non-native-like words. that when participants completed a visual world task and Recall that Spinu and colleagues [131] proposed a simi- were asked to select novel words with phonological over- lar hypothesis, suggesting that more robust subcortical lap with a known language, monolinguals looked more sound encoding could increase the availability of acoustic Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 13 of 24 Table 2 Consequences of bilingualism for speech perception and production Type Region Effect Task Study ACC Functional ACC/SMA Lower > higher proficiency (activation Single word reading Meschyan and Hernandez [149] associated with reading) Frontal cortex/gyrus Functional Speech perception Astheimer et al. [108] Mono ≠ bi (N1 amplitude; largest at word onset, mono only) Mono ≠ bi (P2 positivity in response to Picture-word relatedness (matching vs. Kuipers and Thierry [105] language change, bi only; P2 positivity mismatching) greater for matching than mismatching stimuli, bi only) L IFC Bi > mono (activation) Speech perception Petitto et al. [124] Structural R DLPFC Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter) MFG/IFG Interpreters > control (cortical thickness Proficiency test Mårtensson et al. [139] after training). interpreters ≠ control (+ correlation MFG cortical thickness/ effort; interpreters only) L MFG/L IFG Unbalanced > balanced (cortical thick- Proficiency test Archila-Suerte et al. [142] ness); unbalanced ≠ balanced (− corre- lation foreign accent/MFG surface area) Temporal cortex/gyrus Structural L STG Unbalanced > balanced (cortical thick- Proficiency test Archila-Suerte et al. [142] ness); unbalanced ≠ balanced (− corre- lation foreign accent/STS surface area) STG Interpreters > control (cortical thickness Proficiency test Mårtensson et al. [139] after training). interpreters ≠ control (+ correlation STG cortical thickness/ proficiency; interpreters only) HG Bi > mono (HG volume, gray matter) Ressel et al. [136] Parietal cortex/gyrus Structural R IPL Interpreters < control (white matter) Elmer et al. [87] Occipital cortex/gyrus Structural L MOG/R LOC Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter) Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 14 of 24 Table 2 (continued) Type Region Effect Task Study Subcortical Functional Brainstem Sustained selective attention/speech Krizman et al. [111] Bi > mono (ABR consistency); mono ≠ bi perception (+ correlation: ABR/selective attention, bi only) Brainstem Bi > mono (ABR consistency); mono ≠ bi Attentional control/speech perception Krizman et al. [110] (+ correlation: ABR/attentional control and proficiency, bi only) Brainstem Bi > mono (ABR consistency) Speech perception Krizman et al. [113] Brainstem Bi > mono (FFR) Speech perception Skoe et al. [115] Brainstem Bi > mono (FFR) Speech perception Maggu et al. [114] Brainstem Simultaneous > sequential bilinguals (ABR Speech perception Krizman et al. [112] consistency; + correlation bilingual experience/ABR) L putamen L3 > L2 (activation associated with picture Picture naming Abutalebi et al. [41] naming) Putamen Greater > lower proficiency (activation) Single word reading Meschyan and Hernandez [149] Structural Putamen, thalamus, R CN, L globus Bi > mono (gray matter expansion) Burgaleta et al. [145] pallidus putamen Balanced > unbalanced (volume) Proficiency test Archila-Suerte et al. [142] L putamen Simultaneous > sequential bilinguals Berken et al. [134, 150] (gray matter); simultaneous ≠ sequen- tial bilinguals (+ correlation: gray mat- ter/native-like accent; sequential only). L putamen Bi > mono (gray matter); bi ≠ mono Picture naming Abutalebi et al. [41] (+ correlation: gray matter/L3 profi- ciency; bi only) R Hip Interpreters > control (volume after Proficiency test Mårtensson et al. [139] training). interpreters ≠ control (+ correlation Hip volume/proficiency; interpreters only) Upper corticospinal tract, R CN Interpreters < control (white matter) Elmer et al. [144] Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 15 of 24 Table 2 (continued) Type Region Effect Task Study Multiple/other Functional Bi > mono (ERP amplitude) Selective attention to tones Rämä et al. [109] Bi > mono (early MEG activity showing Oddball paradigm (sound perception) Ferjan Ramírez et al. [125] more acoustic processing of speech stimuli) Bi > mono (bilinguals faster at differentiat - Oddball paradigm (picture-word pairs) Kuipers and Thierry [106] ing languages, as indicated by ERP) Mono ≠ bi (early ERP positivity for Oddball paradigm (picture-word pairs) Kuipers and Thierry [107] semantically matching pictures/words, bi only) IFG, DLPFC, IPL, cerebellum Early bi > late bi (resting functional con- Speech production task Berken et al. [134, 150] nectivity); + correlation (AoA and con- nectivity between L/R IFG for late bi) semantic module (seed: L SMG); phono- Early bi > late bi (resting functional con- Liu et al. [133] logical module (seed: L IFG ) nectivity in both modules) pt Structural CC, IFOF, uncinate fasciculi (UF), SLF Bi > mono (white matter) Pliatsikas et al. [91] SLF, L IFOF, L UF + Correlation (L2 listening experience Kuhl et al. [100] and white matter in UF and anterior IFOF); + correlation (L2 speaking expe- rience and white matter in posterior SLF and IFOF); bi only; mono > bi (white matter) CC, cingulum, AF, L IFOF Bi > mono (white matter); + correlation Rahmani et al. [153] (immersion time and white matter in all but cingulum; bi only) ILF, CC, AF + Correlation (AoA with L IFL, anterior CC, Picture-word matching Nichols and Joanisse [152] AF); + correlation (proficiency with L ILF, R AF, forceps minor of CC) AF Early bi > late bi (white matter) Hämäläinen et al. [154] CC, L anterior insula Interpreters < control (white matter) Elmer et al. [144] Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 16 of 24 signals in auditory sensory memory. This could in turn the IFG, SFG, and STG, which have been associated with allow for more effective recruitment of phonological managing phonological, syntactic, and semantic interfer- working memory, facilitating discrimination of unfamil- ence between languages. Greater functional connectiv- iar phonetic contrasts, and potentially, the acquisition of ity among similar regions (as well as the DMN) has been novel vocabulary. shown to predict how well individuals are able to learn novel words [183]. Given that bilinguals were found to Structural brain matter have greater connectivity within the DMN as well [71], Bilingual experience has been shown to elicit structural structural and functional changes associated with know- changes in regions that support language processing ing multiple languages could potentially facilitate the and acquisition. The first discovery of neurostructural acquisition of additional languages. changes as a result of bilingual experience was reported As previously discussed, one of the most consist- by Mechelli et al. [170], who observed increased gray ently observed effects of bilingualism on white matter matter density in the posterior supramarginal gyrus integrity is in the IFOF [70, 92, 93, 152, 154], the ventral (pSMG; located in the LIPC) for bilinguals compared to stream of the language processing network implicated in monolinguals. The LIPC has been associated with a num - the semantic processing of language [184]. Nichols and ber of functions relevant to language learning, including Joanisse [152] found that, among bilinguals, age of acqui- the maintenance of mental representations, verbal and sition and proficiency were independently correlated phonological working memory, the integration of seman- with FA values in different tracts. While age of acquisi - tic and phonological information, and cognitive con- tion was uniquely and positively associated with bilateral trol [171–176]. Extending Mechelli et al.’s [170] finding, inferior longitudinal fasciculi (ILF) and otherwise pri- Grogan et al. [177] observed increased gray matter in the marily left-lateralized regions, such as of the CC and the pSMG for multilinguals of three or more languages rela- AF, proficiency was uniquely and positively associated tive to bilinguals, indicating that experience-dependent with corresponding right-lateralized regions. The authors changes to this region can vary by the degree of multi- conjecture that the former may reflect the increased lingualism in addition to categorical differences between effort of utilizing an L2 learned later in life, while the lat - monolinguals and bilinguals. Indeed, gray matter density ter may indicate greater efficiency resulting from mas - in the LIPC has been shown to be negatively correlated tery over the language. They additionally point out that with age of acquisition and positively correlated with lan- the relationship between white matter integrity and pro- guage competence among bilinguals [170, 178]. Further- ficiency may either be causally related (such that greater more, Della Rosa et al. [178] observed that the amount proficiency leads to the development of more robust of gray matter was positively associated with cognitive white matter tracts), or else that certain individuals control, as assessed by an Attentional Network Task. may be predisposed to both greater proficiency and the Consistent with the previously discussed neuroprotec- development of higher white matter integrity. Similarly tive function of bilingualism, Abutalebi et al. [179] found ambiguous is whether there is indeed a causal relation- that while monolinguals displayed age-related gray mat- ship between the effects of bilingual experience on struc - ter reductions in the right inferior parietal lobule, no age- tural changes and the ability to acquire new languages related decline was observed for bilinguals. (e.g., L3, L4). Determining the nature of this relationship There is also evidence of greater gray matter volume is particularly difficult when comparing life-long bilin - for older bilinguals compared to monolinguals in the guals and monolinguals, as the two groups naturally vary temporal pole [180], which for bilinguals, is positively in a number of ways other than language experience and correlated with the ability to name pictures in L2 [181]. neural structures. Establishing the causal links between Grogan et al. [177] similarly observed a positive correla- (1) language experience and changes to neural structures, tion between gray matter density in the LIFG and lexical and (2) neural structures and language learning will likely efficiency (as assessed by a lexical decision task), as well require more longitudinal research, as well as controlled as a negative correlation between gray matter and age of experiments that explicitly manipulate language experi- acquisition. While language is generally associated with ence and track outcomes for later learning. left-lateralized regions, Hosoda et al. [77] found that L2 While few studies have employed true random assign- vocabulary size was positively correlated with gray mat- ment to manipulate language experience coupled with ter density in the right IFG, as well as greater white mat- assessments of later language learning, there are several ter integrity in a number of language-related networks. longitudinal studies examining pre- and post-training García-Pentón et al. [182] similarly observed that bilin- correlates of language ability [77, 139, 185]. Stein et al. guals have greater structural connectivity in a number [185] tested English-speaking exchange students learn- of networks that support language processing, including ing German on day 1 of their stay in Switzerland as well Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 17 of 24 Table 3 Consequences of bilingualism for language learning Type Region Effect Task Study ACC Functional ACC/SMA Mono > bi (activation) L2 word learning Bradley et al. [165] Structural ACC + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) Frontal cortex/gyrus Functional R DLPFC Mono > bi (activation) L2 word learning Bradley et al. [165] Structural IFG + Correlation: gray & white English vocabulary test Hosoda et al. [77] matter/L2 vocabulary size (non-training & training) training > control (gray & white matter) Frontal lobe Bi > mono (white matter) Olsen et al. [180] L IFG Bi only: + correlation: gray L2 proficiency Stein et al. [185] matter/improvement of L2 proficiency IFG; L MFG Interpreters > control (C T L2 proficiency Mårtensson et al. [139] change from T1 to T2) Temporal cortex/gyrus Structural STG/R MTG + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) L temporal lobule Bi > mono (gray matter); Picture naming Abutalebi et al. [181] mono ≠ bi (− correlation: bilingualism/effects of aging) Temporal pole Mono ≠ bi (− correlation: Olsen et al. [180] cortical thickness/aging; mono only) Temporal lobe Bi > mono (white matter) Olsen et al. [180] STG Interpreters > control (C T L2 proficiency Mårtensson et al. [139] change from T1 to T2) Parietal cortex/gyrus Functional L IPL Bi only: + correlation gray ANT, language compe- Della Rosa et al. [178] matter/linguistic compe- tence test tence & cognitive control Structural IPL Bi > mono (gray matter); Vocabulary/linguistic back- Abutalebi et al. [78, 179] mono ≠ bi (− correla- ground measures tion: RIPL gray mat- ter/age, mono only); higher > lower profi- ciency (LIPL gray matter); greater > less exposure (RIPL gray matter) pSMG Multi > bi (gray matter Lexical decision Grogan et al. [177] density) pSMG Bi > mono (gray matter); bi L2 proficiency Mechelli et al. [170] only: (+ correlation: gray matter/L2 proficiency) Subcortical Functional Putamen Bi ≠ mono (bi right puta- Proficiency tests Cherodath et al. [166] men, mono both) Putamen Bi > mono (activation) L2 word learning Bradley et al. [165] L CN Mono > bi (activation) L2 word learning Bradley et al. [165] Structural CN + Correlation: gray matter/ English vocabulary test Hosoda et al. [77] L2 vocabulary size (non- training) Putamen, thalamas, globus Bi > mono (expansion), cor- Proficiency test Pliatsikas et al. [86] pallidus relation between immer- sion L2 and structure, not proficiency, in sequential bilinguals Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 18 of 24 Table 3 (continued) Type Region Effect Task Study Multiple/other Functional Learning Brocanto2 Grey et al. [164] Bi ≠ mono (bis showed language native-like EEG responses at low proficiency of artificial language when monos did not, bis better RT and accuracy, reached proficiency sooner than monos) Structural Frontal/temporal/parietal Bi > mono (write matter García-Pentón et al. [182] and occipital/temporal/ connectivity in sub- parietal networks) L IFOF, AC-OL Simultaneous bi > mono & Mohades et al. [92] sequential bi (white mat- ter; IFOF) Simultaneous bi < mono (white mater, AC-OL) R IFG/caudate + Correlation: white matter English vocabulary test Hosoda et al. [77] connectivity/L2 vocabu- lary size (non-training and training) training > control L IFOF Simultaneous bi > monolin- Mohades et al. [93] guals (white matter) R IFOF, anterior thalamic Mono > bi (white matter) Reading test Cummine and Boliek [98] radiation Hippocampus Interpreters > control L2 proficiency Mårtensson et al. [139] (volume change from T1 to T2) as 5 months later when proficiency was significantly systematically consider the interactions among linguis- increased. They observed a significant positive correla - tic, contextual, and neurocognitive factors in order to tion between proficiency and gray matter density in the understand how language acquisition shapes the brain IFG, but no relationship between the absolute values and how particular structures support further learning. of density and proficiency at either time point. Hosoda Table 3 provides an overview of studies on the effects et al. [77] similarly observed training-induced increases of bilingualism on language learning and associated in gray and white matter in the right IFG as well as neural regions. increased white matter in the IFG-caudate tract, which Summary of functional and structural effects of bilin - correlated with improvements in proficiency com - gual experience for tasks and neural regions associated pared to a control group. However, as with Stein et al. with language learning. no correlation between pre-training gray/white matter In sum, bilingual experience can lead to a num- and later proficiency gains was observed. These stud - ber of structural changes to language-related brain ies provide strong evidence that language training can areas, including the LIPC, LIFG, and LATL, as well induce neuroplastic changes, though they did not pro- as white matter tracts connecting language-relevant vide evidence that existing neural structures predicted regions. While it is yet unclear whether such changes subsequent language learning abilities. In contrast, a can account for bilinguals’ improved language learn- number of studies have identified neural predictors of ing, people with multilingual experience often develop enhanced learning, including greater volume in the HG neural characteristics associated with better language [138] and greater frontal–parietal connectivity [132], ability in general. Similarly, bilingual experience can both of which have been shown to increase with mul- enhance cognitive functions that support language tilingual experience [70, 136]. It should be noted that acquisition, such as phonological working memory in addition to different findings across studies, there and the ability to inhibit interference from known lan- were differences in methodology (e.g., training peri - guages. It is therefore possible that the greater capacity ods ranging from 1 day to 5 months) and conceptual to learn new languages brings the effects of bilingualism scope (e.g., assessments of syntactic versus linguistic full circle: the need to manage greater linguistic compe- pitch learning). This variability highlights the need to tition is likely at the origin of numerous neurocognitive Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 19 of 24 inferior occipital gyrus; IPC: inferior parietal cortex; IPL: inferior parietal lobe; changes that may ultimately make it easier for bilin- ITG: inferior temporal gyrus; L: left; L2: second language; L3: third language; guals to acquire and control more competitors. LOC: lateral occipital cortex; MEG: magnetoencephalography; MFG: middle frontal gyrus; MOG: middle occipital gyrus; MTG: middle temporal gyrus; PFC: prefrontal cortex; pSMG: posterior supramarginal gyrus; R: right; SMA: sup- Conclusion plementary motor area; SFG: superior frontal gyrus; SLF: superior longitudinal A lifetime of managing multiple linguistic systems can fasciculi; SOG: superior occipital gyrus; STG: superior temporal gyrus; STS: superior temporal sulcus; UF: uncinate fasciculi; WM: white matter. have dramatic effects on both the function and structure of the bilingual neural architecture. Perhaps most sur- Authors’ contributions prising is the discovery that such changes can develop Both authors contributed to the preparation of the manuscript. Both authors read and approved the final manuscript. with relatively brief amounts of exposure to another lan- guage, highlighting the incredible plasticity of the human brain even into adulthood. The increased demands of Acknowledgements We thank Bennett Nicholas Magliato for assistance with preparing the tables controlling competition from candidates of multiple lan- and the members of the Bilingualism and Psycholinguistics Research Group for guages have been shown to alter how bilinguals engage in their helpful comments. high-level processes such as executive control as well as Competing interests low-level perceptual encoding of sound, including in the The authors declare that they have no competing interests. brainstem. Furthermore, we provide evidence that these effects are likely related, such that top-down attentional Availability of data and materials Not applicable. control may in fact contribute to how lower-level sensory functions operate. These often-beneficial changes at vari - Consent for publication ous levels of processing may, in turn, confer advantages Not applicable. for language learning. Ethics approval and consent to participate The human brain is comprised of highly interactive Not applicable. networks that adapt to serve multiple functions. It would Funding therefore be useful to consider the neural consequences Preparation of this manuscript was supported in part by the National Institute of language experience in a similarly interrelated and of Child Health and Human Development (Grant 2R01 HD059858) to VM. comprehensive manner by studying the reciprocal rela- tionships between different language inputs and levels Publisher’s Note of processing. Given that multilingualism is increasingly Springer Nature remains neutral with regard to jurisdictional claims in pub- lished maps and institutional affiliations. the norm rather than the exception, any model of our linguistic capacity would be incomplete without account- Received: 3 January 2019 Accepted: 16 March 2019 ing for how the brain accommodates multiple languages and the subsequent changes that ripple throughout the neurocognitive system. While a number of studies have investigated the effects of bilingualism on one, or at most, References 1. Thomson H. The “sea-nomad” children who see like dolphins. BBC; two functions at a time (for example, cognitive control 2016. http://www.bbc.com/futur e/story /20160 229-the-sea-nomad and speech perception, or cognitive control and language -child ren-who-see-like-dolph ins. Accessed 28 Nov 2018. learning), even greater integration of tasks tapping into 2. Gislén A, Dacke M, Kröger RH, Abrahamsson M, Nilsson D-E, Warrant EJ. Superior underwater vision in a human population of sea gypsies. Curr different processes could offer a more unified view. By Biol. 2003;13:833–6. https ://doi.org/10.1016/S0960 -9822(03)00290 -2. examining the impact of multilingualism at multiple lev- 3. Maguire EA, Gadian DG, Johnsrude IS, Good CD, Ashburner J, Frackow- els of processing, future work may further illuminate the iak RSJ, et al. Navigation-related structural change in the hippocampi of taxi drivers. PNAS. 2000;97:4398–403. https ://doi.org/10.1073/ interconnected and cascading effects of language experi - pnas.07003 9597. ence that result in widespread consequences for cogni- 4. Gong D, He H, Liu D, Ma W, Dong L, Luo C, et al. Enhanced functional tion and the brain. connectivity and increased gray matter volume of insula related to action video game playing. Sci Rep. 2015;5:9763. https ://doi. org/10.1038/srep0 9763. 5. Driemeyer J, Boyke J, Gaser C, Büchel C, May A. Changes in gray matter Abbreviations induced by learning—revisited. PLoS ONE. 2008;3:e2669. https ://doi. ABR: auditory brainstem response; ACC : anterior cingulate cortex; AC-OL: org/10.1371/journ al.pone.00026 69. anterior third of corpus callosum; AF: arcuate fasciculi; Amg: amygdala; ATL: 6. Penfield W, Roberts L. Speech and brain mechanisms. Princeton: Prince - anterior temporal lobe; BAPSS: bilingual anterior to posterior and subcortical ton University Press; 1959. shift; BEPA: bilingual executive processing advantage; BICA: bilingual inhibitory 7. Macnamara J. The bilingual’s linguistic performance—a psy- control advantage; Cb: cerebellum; CC: corpus callosum; CN: caudate nucleus; chological overview. J Soc Issues. 1967;23:58–77. https ://doi. CRN: correct response negativity; DLPFC: dorsolateral prefrontal cortex; EEG: org/10.1111/j.1540-4560.1967.tb005 76.x. electroencephalogram; ERN: error-related negativity; ERP: event-related poten- 8. Gonzales K, Byers-Heinlein K, Lotto AJ. How bilinguals perceive speech tial; FFR: frequency following response; fMRI: functional magnetic resonance depends on which language they think they’re hearing. Cognition. imaging; HG: Heschel’s gyrus; Hip: hippocampus; IFG: inferior frontal gyrus; 2019;182:318–30. https ://doi.org/10.1016/j.cogni tion.2018.08.021. IFOF: inferior frontal-occipital fasciculi; ILF: inferior longitudinal fasciculi; IOG: Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 20 of 24 9. Molnar M, Ibáñez-Molina A, Carreiras M. Interlocutor identity affects 30. Morales L, Paolieri D, Dussias PE, Kroff JRV, Gerfen C, Bajo MT. The language activation in bilinguals. J Mem Lang. 2015;81:91–104. https :// gender congruency effect during bilingual spoken-word recognition. doi.org/10.1016/j.jml.2015.01.002. Bilingualism. 2016;19:294–310. https ://doi.org/10.1017/S1366 72891 10. Quam C, Creel SC. Mandarin-English bilinguals process lexical tones in 50001 76. newly learned words in accordance with the language context. PLoS 31. Kroll JF, Bobb SC, Misra M, Guo T. Language selection in bilingual ONE. 2017;12:e0169001. https ://doi.org/10.1371/journ al.pone.01690 01. speech: Evidence for inhibitory processes. Acta Psychol (Amst). 11. Shook A, Marian V. The influence of native-language tones on lexical 2008;128:416–30. https ://doi.org/10.1016/j.actps y.2008.02.001. access in the second language. J Acoust Soc Am. 2016;139:3102–9. 32. Green DW, Abutalebi J. Language control in bilinguals: The adap- https ://doi.org/10.1121/1.49536 92. tive control hypothesis. J Cogn Psychol. 2013;25:515–30. https ://doi. 12. Spivey MJ, Marian V. Cross talk between native and second languages: org/10.1080/20445 911.2013.79637 7. partial activation of an irrelevant lexicon. Psychol Sci. 1999;10:281– 33. Abutalebi J, Green DW. Neuroimaging of language control in bilinguals: 4. https ://doi.org/10.1111/1467-9280.00151 . neural adaptation and reserve. Bilingualism. 2016;19:689–98. https :// 13. Shook A, Marian V. Bimodal bilinguals co-activate both languages dur-doi.org/10.1017/S1366 72891 60002 25. ing spoken comprehension. Cognition. 2012;124:314–24. https ://doi. 34. Branzi FM, Calabria M, Boscarino ML, Costa A. On the overlap between org/10.1016/j.cogni tion.2012.05.014. bilingual language control and domain-general executive control. 14. Weber A, Cutler A. Lexical competition in non-native spoken-word Acta Psychol (Amst). 2016;166:21–30. https ://doi.org/10.1016/j.actps recognition. J Mem Lang. 2004;50:1–25. https ://doi.org/10.1016/S0749 y.2016.03.001. -596X(03)00105 -0. 35. Hernandez AE, Martinez A, Kohnert K. In search of the language switch: 15. Blumenfeld HK, Marian V. Constraints on parallel activation in bilingual an fMRI study of picture naming in Spanish-English bilinguals. Brain spoken language processing: Examining proficiency and lexical status Lang. 2000;73:421–31. https ://doi.org/10.1006/brln.1999.2278. using eye-tracking. Lang Cogn Process. 2007;22:633–60. https ://doi. 36. Hernandez AE. Language switching in the bilingual brain: what’s org/10.1080/01690 96060 10007 46. next? Brain Lang. 2009;109:133–40. https ://doi.org/10.1016/j.bandl 16. Marian V, Spivey M, Hirsch J. Shared and separate systems in bilingual .2008.12.005. language processing: converging evidence from eyetracking and brain 37. Garbin G, Costa A, Sanjuan A, Forn C, Rodriguez-Pujadas A, Ventura N, imaging. Brain Lang. 2003;86:70–82. https ://doi.org/10.1016/S0093 et al. Neural bases of language switching in high and early proficient -934X(02)00535 -7. bilinguals. Brain Lang. 2011;119:129–35. https ://doi.org/10.1016/j.bandl 17. Marian V, Spivey M. Bilingual and monolingual processing of compet- .2011.03.011. ing lexical items. Appl Psycholinguist. 2003;24:173–93. https ://doi. 38. Seo R, Stocco A, Prat CS. The bilingual language network: differential org/10.1017/S0142 71640 30000 92. involvement of anterior cingulate, basal ganglia and prefrontal cortex in 18. Ju M, Luce PA. Falling on sensitive ears: Constraints on bilingual preparation, monitoring, and execution. Neuroimage. 2018;174:44–56. lexical activation. Psychol Sci. 2004;15:314–8. https ://doi.org/10.111https ://doi.org/10.1016/j.neuro image .2018.02.010. 1/j.0956-7976.2004.00675 .x. 39. Abutalebi J, Green DW. Control mechanisms in bilingual language pro- 19. Cutler A, Weber A, Otake T. Asymmetric mapping from phonetic to lexi- duction: neural evidence from language switching studies. Lang Cogn cal representations in second-language listening. J Phon. 2006;34:269– Process. 2008;23:557–82. https ://doi.org/10.1080/01690 96080 19206 02. 84. https ://doi.org/10.1016/j.wocn.2005.06.002. 40. Zou L, Ding G, Abutalebi J, Shu H, Peng D. Structural plasticity of the left 20. Giezen MR, Blumenfeld HK, Shook A, Marian V, Emmorey K. Parallel caudate in bimodal bilinguals. Cortex. 2012;48:1197–206. https ://doi. language activation and inhibitory control in bimodal bilinguals. Cogni-org/10.1016/j.corte x.2011.05.022. tion. 2015;141:9–25. https ://doi.org/10.1016/j.cogni tion.2015.04.009. 41. Abutalebi J, Della Rosa PA, Castro Gonzaga AK, Keim R, Costa A, Perani 21. Thierry G, Wu YJ. Electrophysiological evidence for language interfer- D. The role of the left putamen in multilingual language produc- ence in late bilinguals. Neuroreport. 2004;15:1555–8. https ://doi. tion. Brain Lang. 2013;125:307–15. https ://doi.org/10.1016/j.bandl org/10.1097/01.wnr.00001 34214 .57469 .c2. .2012.03.009. 22. Hoshino N, Thierry G. Do Spanish-English bilinguals have their fingers 42. Stocco A, Lebiere C, Anderson JR. Conditional routing of information to in two pies—or is it their toes? An electrophysiological investigation the cortex: a model of the basal ganglia’s role in cognitive coordination. of semantic access in bilinguals. Front Psychol. 2012;3:9. https ://doi. Psychol Rev. 2010;117:541–74. https ://doi.org/10.1037/a0019 077. org/10.3389/fpsyg .2012.00009 . 43. Bialystok E, Craik FIM, Luk G. Bilingualism: consequences for mind 23. Chen P, Bobb SC, Hoshino N, Marian V. Neural signatures of language and brain. Trends Cogn Sci. 2012;16:240–50. https ://doi.org/10.1016/j. co-activation and control in bilingual spoken word comprehen- tics.2012.03.001. sion. Brain Res. 2017;1665:50–64. https ://doi.org/10.1016/j.brain 44. Bialystok E, Martin MM, Viswanathan M. Bilingualism across the lifespan: res.2017.03.023. The rise and fall of inhibitory control. Int J Biling. 2005;9:109–19. https :// 24. Carrasco-Ortiz H, Midgley KJ, Frenck-Mestre C. Are phonological repre-doi.org/10.1177/13670 06905 00900 10701 . sentations in bilinguals language specific? An ERP study on interlingual 45. Marian V, Chabal S, Bartolotti J, Bradley K, Hernandez AE. Differential homophones. Psychophysiology. 2012;49:531–43. https ://doi.org/10.11 recruitment of executive control regions during phonological competi- 11/j.1469-8986.2011.01333 .x. tion in monolinguals and bilinguals. Brain Lang. 2014;139:108–17. https 25. Guo T, Peng D. Event-related potential evidence for parallel activa-://doi.org/10.1016/j.bandl .2014.10.005. tion of two languages in bilingual speech production. Neuroreport. 46. Abutalebi J, Della Rosa PA, Green DW, Hernandez M, Scifo P, Keim R, 2006;17:1757–60. https ://doi.org/10.1097/01.wnr.00002 46327 .89308 .a5. et al. Bilingualism tunes the anterior cingulate cortex for conflict moni- 26. Thierry G, Wu YJ. Brain potentials reveal unconscious translation during toring. Cereb Cortex. 2012;22:2076–86. https ://doi.org/10.1093/cerco r/ foreign-language comprehension. Proc Natl Acad Sci. 2007;104:12530–bhr28 7. 5. https ://doi.org/10.1073/pnas.06099 27104 . 47. Garbin G, Sanjuan A, Forn C, Bustamante JC, Rodriguez-Pujadas A, Bel- 27. Allopenna PD, Magnuson JS, Tanenhaus MK. Tracking the time course loch V, et al. Bridging language and attention: brain basis of the impact of spoken word recognition using eye movements: Evidence for of bilingualism on cognitive control. Neuroimage. 2010;53:1272–8. continuous mapping models. J Mem Lang. 1998;38:419–39. https ://doi.https ://doi.org/10.1016/j.neuro image .2010.05.078. org/10.1006/jmla.1997.2558. 48. Becker TM, Prat CS, Stocco A. A network-level analysis of cognitive 28. Huettig F, Rommers J, Meyer AS. Using the visual world paradigm flexibility reveals a differential influence of the anterior cingulate cortex to study language processing: A review and critical evaluation. Acta in bilinguals versus monolinguals. Neuropsychologia. 2016;85:62–73. Psychol (Amst). 2011;137:151–71. https ://doi.org/10.1016/j.actps https ://doi.org/10.1016/j.neuro psych ologi a.2016.01.020. y.2010.11.003. 49. Dong Y, Zhong F. Interpreting experience enhances early attentional 29. Macizo P, Bajo T, Cruz Martín M. Inhibitory processes in bilingual processing, conflict monitoring and interference suppression along the language comprehension: Evidence from Spanish-English interlexical time course of processing. Neuropsychologia. 2017;95:193–203. https :// homographs. J Mem Lang. 2010;63:232–44. https ://doi.org/10.1016/j.doi.org/10.1016/j.neuro psych ologi a.2016.12.007. jml.2010.04.002. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 21 of 24 50. Kałamała P, Drożdżowicz A, Szewczyk J, Marzecová A, Wodniecka Z. 69. Waldie KE, Badzakova-Trajkov G, Miliivojevic B, Kirk IJ. Neural activ- Task strategy may contribute to performance differences between ity during Stroop colour-word task performance in late proficient monolinguals and bilinguals in cognitive control tasks: ERP evidence. bilinguals: a functional Magnetic Resonance Imaging study. Psychol J Neurolinguistics. 2018;46:78–92. https ://doi.org/10.1016/j.jneur oling Neurosci. 2009;2:125–36. https ://doi.org/10.3922/j.psns.2009.2.004. .2017.12.013. 70. Luk G, Bialystok E, Craik FIM, Grady CL. Lifelong bilingualism maintains 51. Kousaie S, Phillips NA. Conflict monitoring and resolution: Are two white matter integrity in older adults. J Neurosci. 2011;31:16808– languages better than one? Evidence from reaction time and event- 13. https ://doi.org/10.1523/JNEUR OSCI.4563-11.2011. related brain potentials. Brain Res. 2012;1446:71–90. https ://doi. 71. Grady CL, Luk G, Craik FIM, Bialystok E. Brain network activity in mono- org/10.1016/j.brain res.2012.01.052. lingual and bilingual older adults. Neuropsychologia. 2015;66:170– 52. Morales J, Yudes C, Gómez-Ariza CJ, Bajo MT. Bilingualism modulates 81. https ://doi.org/10.1016/j.neuro psych ologi a.2014.10.042. dual mechanisms of cognitive control: evidence from ERPs. Neuropsy- 72. Buckner RL, Sepulcre J, Talukdar T, Krienen FM, Liu H, Hedden T, et al. chologia. 2015;66:157–69. https ://doi.org/10.1016/j.neuro psych ologi Neurobiology of disease cortical hubs revealed by intrinsic functional a.2014.11.014. connectivity: mapping, assessment of stability, and relation to Alzhei- 53. Nieuwenhuis S, Yeung N, van den Wildenberg W, Ridderinkhof KR. Elec- mer’s disease. J Neurosci. 2009;29:1860–73. https ://doi.org/10.1523/ trophysiological correlates of anterior cingulate function in a go/no-go JNEUR OSCI.5062-08.2009. task: effects of response conflict and trial type frequency. Cogn Aec ff t 73. Dang LC, O’Neil JP, Jagust WJ. Genetic effects on behavior are mediated Behav Neurosci. 2003;3:17–26. https ://doi.org/10.3758/CABN.3.1.17. by neurotransmitters and large-scale neural networks. Neuroimage. 54. Falkenstein M, Hoormann J, Hohnsbein J. Inhibition-related 2013;66:203–14. https ://doi.org/10.1016/j.neuro image .2012.10.090. ERP components: Variation with modality, age, and time-on- 74. Cole MW, Reynolds JR, Power JD, Repovs G, Anticevic A, Braver TS. Multi- task. EBSCOhost. J Psychophysiol. 2002;16:167–75. https ://doi. task connectivity reveals flexible hubs for adaptive task control. Nat org/10.1027//0269-8803.16.3.167. Neurosci. 2013;16:1348–55. https ://doi.org/10.1038/nn.3470. 55. Melara RD, Wang H, Vu KPL, Proctor RW. Attentional origins of the 75. Olulade OA, Jamal NI, Koo DS, Perfetti CA, LaSasso C, Eden GF. Neu- Simon effect: Behavioral and electrophysiological evidence. Brain Res. roanatomical evidence in support of the bilingual advantage theory. 2008;1215:147–59. https ://doi.org/10.1016/j.brain res.2008.03.026. Cereb Cortex. 2016;26:3196–204. https ://doi.org/10.1093/cerco r/bhv15 56. Mathalon DH, Whitfield SL, Ford JM. Anatomy of an error: ERP and 2. fMRI. Biol Psychol. 2003;64:119–41. https ://doi.org/10.1016/S0301 76. Hervais-Adelman A, Egorova N, Golestani N. Beyond bilingualism: mul- -0511(03)00105 -4. tilingual experience correlates with caudate volume. Brain Struct Funct. 57. Fernandez M, Tartar JL, Padron D, Acosta J. Neurophysiological marker 2018;223:3495–502. https ://doi.org/10.1007/s0042 9-018-1695-0. of inhibition distinguishes language groups on a non-linguistic execu- 77. Hosoda C, Tanaka K, Nariai T, Honda M, Hanakawa T. Dynamic neural tive function test. Brain Cogn. 2013;83:330–6. https ://doi.org/10.1016/j. network reorganization associated with second language vocabulary bandc .2013.09.010. acquisition: a multimodal imaging study. J Neurosci. 2013;33:13663–72. 58. Moreno S, Wodniecka Z, Tays W, Alain C, Bialystok E. Inhibitory control https ://doi.org/10.1523/JNEUR OSCI.0410-13.2013. in bilinguals and musicians: event related potential (ERP) evidence 78. Abutalebi J, Guidi L, Borsa V, Canini M, Della Rosa PA, Parris BA, et al. for experience-specific effects. PLoS ONE. 2014;9:e94169. https ://doi. Bilingualism provides a neural reserve for aging populations. Neuropsy- org/10.1371/journ al.pone.00941 69. chologia. 2015;69:201–10. https ://doi.org/10.1016/j.neuro psych ologi 59. Kousaie S, Phillips NA. A behavioural and electrophysiological inves- a.2015.01.040. tigation of the effect of bilingualism on aging and cognitive control. 79. Miller EK, Cohen JD. An integrative theory of prefrontal cortex function. Neuropsychologia. 2017;94:23–35. https ://doi.org/10.1016/j.neuro psych Annu Rev Neurosci. 2001;24:167–202. https ://doi.org/10.1146/annur ologi a.2016.11.013.ev.neuro .24.1.167. 60. Hilchey MD, Klein RM. Are there bilingual advantages on nonlinguistic 80. Hernandez AE, Dapretto M, Mazziotta J, Bookheimer S. Language interference tasks? Implications for the plasticity of executive control switching and language representation in Spanish-English bilinguals: processes. Psychon Bull Rev. 2011;18:625–58. https ://doi.org/10.3758/ an fMRI study. Neuroimage. 2001;14:510–20. https ://doi.org/10.1006/ s1342 3-011-0116-7. nimg.2001.0810. 61. Coderre EL, van Heuven WJB. Electrophysiological explorations of 81. Alladi S, Bak TH, Duggirala V, Surampudi B, Shailaja M, Shukla AK, et al. the bilingual advantage: evidence from a stroop task. PLoS ONE. Bilingualism delays age at onset of dementia, independent of educa- 2014;9:e103424. https ://doi.org/10.1371/journ al.pone.01034 24. tion and immigration status. Neurology. 2013;81:1938–44. https ://doi. 62. Heidlmayr K, Hemforth B, Moutier S, Isel F. Neurodynamics of executive org/10.1212/01.wnl.00004 36620 .33155 .a4. control processes in bilinguals: evidence from ERP and source recon- 82. Bialystok E, Craik FIM, Freedman M. Bilingualism as a protection against struction analyses. Front Psychol. 2015;6:821. https ://doi.org/10.3389/ the onset of symptoms of dementia. Neuropsychologia. 2007;45:459– fpsyg .2015.00821 /abstr act. 64. https ://doi.org/10.1016/j.neuro psych ologi a.2006.10.009. 63. Anderson JAE, Chung-Fat-Yim A, Bellana B, Luk G, Bialystok E. Language 83. Botvinick M, Nystrom LE, Fissell K, Carter CS, Cohen JD. Conflict moni- and cognitive control networks in bilinguals and monolinguals. Neu- toring versus selection-for-action in anterior cingulate cortex. Nature. ropsychologia. 2018;117:352–63. https ://doi.org/10.1016/j.neuro psych 1999;402:179–81. https ://doi.org/10.1038/46035 . ologi a.2018.06.023. 84. Wang Y, Xue G, Chen C, Xue F, Dong Q. Neural bases of asymmetric 64. Coderre EL, Smith JF, Van Heuven WJB, Horwitz B. The functional language switching in second-language learners: An ER-fMRI study. overlap of executive control and language processing in bilinguals. Neuroimage. 2007;35:862–70. https ://doi.org/10.1016/j.neuro image Bilingualism. 2016;19:471–88. https ://doi.org/10.1017/S1366 72891 .2006.09.054. 50001 88. 85. Deluca V, Rothman J, Pliatsikas C. Linguistic immersion and structural 65. Timmer K, Grundy JG, Bialystok E. Earlier and more distributed neural effects on the bilingual brain: a longitudinal study. Biling Lang Cogn. networks for bilinguals than monolinguals during switching. Neuropsy- 2018. https ://doi.org/10.1017/S1366 72891 80008 83. chologia. 2017;106:245–60. https ://doi.org/10.1016/j.neuro psych ologi 86. Pliatsikas C, DeLuca V, Moschopoulou E, Saddy JD. Immersive bilingual- a.2017.09.017. ism reshapes the core of the brain. Brain Struct Funct. 2017;222:1785– 66. Grundy JG, Anderson JAE, Bialystok E. Neural correlates of cogni- 95. https ://doi.org/10.1007/s0042 9-016-1307-9. tive processing in monolinguals and bilinguals. Ann N Y Acad Sci. 87. Elmer S, Hänggi J, Jäncke L. Processing demands upon cognitive, 2017;1396:183–201. https ://doi.org/10.1111/nyas.13333 . linguistic, and articulatory functions promote grey matter plasticity in 67. Marian V, Bartolotti J, Rochanavibhata S, Bradley K, Hernandez AE. Bilin- the adult multilingual brain: insights from simultaneous interpreters. gual cortical control of between- and within-language competition. Sci Cortex. 2014;54:179–89. https ://doi.org/10.1016/j.corte x.2014.02.014. Rep. 2017;7:11763. https ://doi.org/10.1038/s4159 8-017-12116 -w. 88. Filippi R, Richardson FM, Dick F, Leech R, Green DW, Thomas MSC, et al. 68. Grundy JG, Anderson JAE, Bialystok E. Bilinguals have more complex The right posterior paravermis and the control of language interfer- EEG brain signals in occipital regions than monolinguals. Neuroimage. ence. J Neurosci. 2011;31:10732–40. https ://doi.org/10.1523/JNEUR 2017;159:280–8. https ://doi.org/10.1016/j.neuro image .2017.07.063. OSCI.1783-11.2011. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 22 of 24 89. Pliatsikas C, Johnstone T, Marinis T. Grey matter volume in the cerebel- 109. Rämä P, Leminen A, Koskenoja-Vainikka S, Leminen M, Alho K, Kujala T. lum is related to the processing of grammatical rules in a second Eec ff t of language experience on selective auditory attention: an event- language: a structural voxel-based morphometry study. Cerebellum. related potential study. Int J Psychophysiol. 2018;127:38–45. https ://doi. 2014;13:55–63. https ://doi.org/10.1007/s1231 1-013-0515-6.org/10.1016/j.ijpsy cho.2018.03.007. 90. Schlegel AA, Rudelson JJ, Tse PU. White matter structure changes as 110. Krizman J, Skoe E, Marian V, Kraus N. Bilingualism increases neural adults learn a second language. J Cogn Neurosci. 2012;24:1664–70. response consistency and attentional control: evidence for sensory https ://doi.org/10.1162/jocn_a_00240 . and cognitive coupling. Brain Lang. 2014;128:34–40. https ://doi. 91. Pliatsikas C, Moschopoulou E, Saddy JD. The effects of bilingualism on org/10.1016/j.bandl .2013.11.006. the white matter structure of the brain. PNAS. 2015;112:1334–7. https :// 111. Krizman J, Marian V, Shook A, Skoe E, Kraus N. Subcortical encoding doi.org/10.1073/pnas.14141 83112 . of sound is enhanced in bilinguals and relates to executive func- 92. Mohades SG, Struys E, Van Schuerbeek P, Mondt K, Van De Craen P, tion advantages. Proc Natl Acad Sci. 2012;109:7877–81. https ://doi. Luypaert R. DTI reveals structural differences in white matter tracts org/10.1073/pnas.12015 75109 . between bilingual and monolingual children. Brain Res. 2012;1435:72– 112. Krizman J, Slater J, Skoe E, Marian V, Kraus N. Neural processing of 80. https ://doi.org/10.1016/j.brain res.2011.12.005. speech in children is influenced by extent of bilingual experience. Neu- 93. Mohades SG, Van Schuerbeek P, Rosseel Y, Van De Craen P, Luypaert rosci Lett. 2015;585:48–53. https ://doi.org/10.1016/j.neule t.2014.11.011. R, Baeken C. White-matter development is different in bilingual 113. Krizman J, Skoe E, Kraus N. Bilingual enhancements have no socioeco- and monolingual children: a longitudinal DTI study. PLoS ONE. nomic boundaries. Dev Sci. 2016;19:881–91. https ://doi.org/10.1111/ 2015;10:e0117968. https ://doi.org/10.1371/journ al.pone.01179 68. desc.12347 . 94. Zhang J, Zhu X, Wang X, Gao J, Shi H, Huang B, et al. Increased structural 114. Maggu AR, Zong W, Law V, Wong PCM. Learning two tone languages connectivity in corpus callosum in adolescent males with conduct enhances the brainstem encoding of lexical tones. Proc Interspeech. disorder. J Am Acad Child Adolesc Psychiatry. 2014;53(466.e1):475.e1. 2018;2018:1437–41. https ://doi.org/10.21437 /Inter speec h.2018-2130. https ://doi.org/10.1016/j.jaac.2013.12.015. 115. Skoe E, Burakiewicz E, Figueiredo M, Hardin M. Basic neural processing 95. Just MA, Cherkassky VL, Keller TA, Kana RK, Minshew NJ. Functional and of sound in adults is influenced by bilingual experience. Neuroscience. anatomical cortical underconnectivity in autism: evidence from an fMRI 2017;349:278–90. https ://doi.org/10.1016/j.neuro scien ce.2017.02.049. study of an executive function task and corpus callosum morphometry. 116. Song JH, Skoe E, Wong PCM, Kraus N. Plasticity in the adult human Cereb Cortex. 2007;17:951–61. https ://doi.org/10.1093/cerco r/bhl00 6. auditory brainstem following short-term linguistic training. J Cogn 96. Duffau H. The anatomo-functional connectivity of language revisited: Neurosci. 2008;20:1892–902. https ://doi.org/10.1162/jocn.2008.20131 . New insights provided by electrostimulation and tractography. Neu- 117. Krishnan A, Xu Y, Gandour J, Cariani P. Encoding of pitch in the human ropsychologia. 2008;46:927–34. https ://doi.org/10.1016/j.neuro psych brainstem is sensitive to language experience. Cogn Brain Res. ologi a.2007.10.025. 2005;25:161–8. https ://doi.org/10.1016/j.cogbr ainre s.2005.05.004. 97. Almairac F, Herbet G, Moritz-Gasser S, de Champfleur NM, Duffau H. The 118. Anderson S, Skoe E, Chandrasekaran B, Zecker S, Kraus N. Brainstem left inferior fronto-occipital fasciculus subserves language semantics: correlates of speech-in-noise perception in children. Hear Res. a multilevel lesion study. Brain Struct Funct. 2015;220:1983–95. https :// 2010;270:151–7. https ://doi.org/10.1016/j.heare s.2010.08.001. doi.org/10.1007/s0042 9-014-0773-1. 119. Song JH, Skoe E, Banai K, Kraus N. Perception of speech in noise: Neural 98. Cummine J, Boliek CA. Understanding white matter integrity stability correlates. J Cogn Neurosci. 2011;23:2268–79. https ://doi.org/10.1162/ for bilinguals on language status and reading performance. Brain Struct jocn.2010.21556 . Funct. 2013;218:595–601. https ://doi.org/10.1007/s0042 9-012-0466-6. 120. Krishnan A, Gandour JT, Bidelman GM. The effects of tone language 99. Gold BT, Johnson NF, Powell DK. Lifelong bilingualism contributes to experience on pitch processing in the brainstem. J Neurolinguistics. cognitive reserve against white matter integrity declines in aging. Neu- 2010;23:81–95. https ://doi.org/10.1016/j.jneur oling .2009.09.001. ropsychologia. 2013;51:2841–6. https ://doi.org/10.1016/j.neuro psych 121. Zhao TC, Kuhl PK. Linguistic effect on speech perception observed at ologi a.2013.09.037. the brainstem. Proc Natl Acad Sci. 2018;115:201800186. https ://doi. 100. Kuhl PK, Stevenson J, Corrigan NM, van den Bosch JJF, Can DD, Richards org/10.1073/pnas.18001 86115 . T. Neuroimaging of the bilingual brain: structural brain correlates of 122. Strange W, Jenkins JJ. Role of linguistic experience in the per- listening and speaking in a second language. Brain Lang. 2016;162:1–9. ception of speech. Perception Exp. 1978;1:129–69. https ://doi. https ://doi.org/10.1016/j.bandl .2016.07.004. org/10.1007/978-1-4684-2619-9_5. 101. Douet V, Chang L. Fornix as an imaging marker for episodic memory 123. Bidelman GM, Gandour JT, Krishnan A. Cross-domain effects of music deficits in healthy aging and in various neurological disorders. Front and language experience on the representation of pitch in the human Aging Neurosci. 2015;6:343. https ://doi.org/10.3389/fnagi .2014.00343 / auditory brainstem. J Cogn Neurosci. 2011;23:425–34. https ://doi. abstr act. org/10.1162/jocn.2009.21362 . 102. Ye Z, Zhou X. Executive control in language processing. Neurosci 124. Petitto LA, Berens MS, Kovelman I, Dubins MH, Jasinska K, Shalinsky M. Biobehav Rev. 2009;33:1168–77. https ://doi.org/10.1016/j.neubi The “Perceptual Wedge Hypothesis” as the basis for bilingual babies’ orev.2009.03.003. phonetic processing advantage: new insights from fNIRS brain imag- 103. Anderson MC, Green C. Suppressing unwanted memories by executive ing. Brain Lang. 2012;121:130–43. https ://doi.org/10.1016/j.bandl control. Nature. 2014;410:366–9. https ://doi.org/10.1038/35066 572. .2011.05.003. 104. Wardlow L. Individual differences in speakers’ perspective taking: the 125. Ferjan Ramírez N, Ramírez RR, Clarke M, Taulu S, Kuhl PK. Speech roles of executive control and working memory. Psychon Bull Rev. discrimination in 11-month-old bilingual and monolingual infants: a 2013;20:766–72. https ://doi.org/10.3758/s1342 3-013-0396-1. magnetoencephalography study. Dev Sci. 2017;20:e12427. https ://doi. 105. Kuipers J-R, Thierry G. Event-related brain potentials reveal the time- org/10.1111/desc.12427. course of language change detection in early bilinguals. Neuroimage. 126. Singh L. Bilingual infants demonstrate advantages in learning words in 2010;50:1633–8. https ://doi.org/10.1016/j.neuro image .2010.01.076. a third language. Child Dev. 2018;89:e397–413. https ://doi.org/10.1111/ 106. Kuipers JR, Thierry G. Event-related potential correlates of language cdev.12852. change detection in bilingual toddlers. Dev Cogn Neurosci. 2012;2:97– 127. Tremblay M-C, Sabourin L. Comparing behavioral discrimination and 102. https ://doi.org/10.1016/j.dcn.2011.08.002. learning abilities in monolinguals, bilinguals and multilinguals. J Acoust 107. Kuipers JR, Thierry G. Bilingualism and increased attention to speech: Soc Am. 2012;132:3465–74. https ://doi.org/10.1121/1.47569 55. evidence from event-related potentials. Brain Lang. 2015;149:27–32. 128. Werker JF. The effect of multilingualism on phonetic perceptual flexibil- https ://doi.org/10.1016/j.bandl .2015.07.004. ity. Appl Psycholinguist. 1986;7:141–55. https ://doi.org/10.1017/S0142 108. Astheimer LB, Berkes M, Bialystok E. Differential allocation of atten-71640 00073 60. tion during speech perception in monolingual and bilingual listeners. 129. Antoniou M, Liang E, Ettlinger M, Wong PCM. The bilingual advan- Lang Cogn Neurosci. 2016;31:196–205. https ://doi.org/10.1080/23273 tage in phonetic learning. Bilingualism. 2015;18:683–95. https ://doi. 798.2015.10831 14.org/10.1017/S1366 72891 40007 77. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 23 of 24 130. Wang T, Saffran JR. Statistical learning of a tonal language: the influ- Neuroimage. 2006;29:1135–40. https ://doi.org/10.1016/j.neuro image ence of bilingualism and previous linguistic experience. Front Psychol. .2005.08.055. 2014;5:1–9. https ://doi.org/10.3389/fpsyg .2014.00953 . 150. Berken JA, Gracco VL, Chen JK, Klein D. The timing of language learning 131. Spinu LE, Hwang J, Lohmann R. Is there a bilingual advantage in shapes brain structure associated with articulation. Brain Struct Funct. phonetic and phonological acquisition? The initial learning of word- 2016;221:3591–600. https ://doi.org/10.1007/s0042 9-015-1121-9. final coronal stop realization in a novel accent of English. Int J Biling. 151. Dick AS, Tremblay P. Beyond the arcuate fasciculus: consensus 2018;22:350–70. https ://doi.org/10.1177/13670 06916 68108 0. and controversy in the connectional anatomy of language. Brain. 132. Ventura-Campos N, Sanjuán A, González J, Ngeles Palomar-García M-A, 2012;135:3529–50. https ://doi.org/10.1093/brain /aws22 2. Rodríguez-Pujadas A, Sebastián-Gallés N, et al. Spontaneous brain activ- 152. Nichols ES, Joanisse MF. Functional activity and white matter micro- ity predicts learning ability of foreign sounds. J Neurosci. 2013;33:9295– structure reveal the independent effects of age of acquisition and pro - 305. https ://doi.org/10.1523/JNEUR OSCI.4655-12.2013. ficiency on second-language learning. Neuroimage. 2016;143:15–25. 133. Liu X, Tu L, Wang J, Jiang B, Gao W, Pan X, et al. Onset age of L2 acquisi-https ://doi.org/10.1016/j.neuro image .2016.08.053. tion influences language network in early and late Cantonese-Man- 153. Rahmani F, Sobhani S, Aarabi MH. Sequential language learning and darin bilinguals. Brain Lang. 2017;174:16–28. https ://doi.org/10.1016/j. language immersion in bilingualism: diffusion MRI connectometry bandl .2017.07.003. reveals microstructural evidence. Exp Brain Res. 2017;235:2935–45. 134. Berken JA, Chai X, Chen J-K, Gracco VL, Klein D. Eec ff ts of Early and https ://doi.org/10.1007/s0022 1-017-5029-x. Late Bilingualism on Resting-State Functional Connectivity. J Neurosci. 154. Hämäläinen S, Sairanen V, Leminen A, Lehtonen M. Bilingualism 2016;36:1165–72. https ://doi.org/10.1523/JNEUR OSCI.1960-15.2016. modulates the white matter structure of language-related pathways. 135. Callan DE, Kawato M, Parsons L, Turner R. Speech and song: the Neuroimage. 2017;152:249–57. https ://doi.org/10.1016/j.neuro image role of the cerebellum. Cerebellum. 2007;6:321–7. https ://doi. .2017.02.081. org/10.1080/14734 22060 11877 33. 155. Bartolotti J, Marian V. Language learning and control in monolinguals 136. Ressel V, Pallier C, Ventura-Campos N, Diaz B, Roessler A, Avila C, and bilinguals. Cogn Sci. 2012;36:1129–47. https ://doi.org/10.111 et al. An effect of bilingualism on the auditory cortex. J Neurosci. 1/j.1551-6709.2012.01243 .x. 2012;32:16597–601. https ://doi.org/10.1523/JNEUR OSCI.1996-12.2012. 156. Bartolotti J, Marian V, Schroeder SR, Shook A. Bilingualism and inhibitory 137. Golestani N, Molko N, Dehaene S, LeBihan D, Pallier C. Brain struc- control influence statistical learning of novel word forms. Front Psychol. ture predicts the learning of foreign speech sounds. Cereb Cortex. 2011;2:1–10. https ://doi.org/10.3389/fpsyg .2011.00324 . 2007;17:575–82. https ://doi.org/10.1093/cerco r/bhk00 1. 157. Kaushanskaya M, Marian V. Age-of-acquisition effects in the develop - 138. Wong PCM, Warrier CM, Penhune VB, Roy AK, Sadehh A, Parrish TB, et al. ment of a bilingual advantage for word learning. In: Proceedings of the Volume of left Heschl’s gyrus and linguistic pitch learning. Cereb Cortex. 32nd annual Boston University conference on language development; 2008;18:828–36. https ://doi.org/10.1093/cerco r/bhm11 5. 2007. p. 213–24. https ://pdfs.seman ticsc holar .org/c880/0a8f1 cf5e1 139. Mårtensson J, Eriksson J, Bodammer NC, Lindgren M, Johansson 038b3 af377 2821f d8b33 4785f 0.pdf. Accessed 20 Nov 2018. M, Nyberg L, et al. Growth of language-related brain areas after 158. Kaushanskaya M, Marian V. The bilingual advantage in novel word foreign language learning. Neuroimage. 2012;63:240–4. https ://doi. learning. Psychon Bull Rev. 2009;16:705–10. https ://doi.org/10.3758/ org/10.1016/j.neuro image .2012.06.043. PBR.16.4.705. 140. Price CJ. The anatomy of language: a review of 100 fMRI studies pub- 159. Kaushanskaya M, Marian V. Bilingualism reduces native-language inter- lished in 2009. Ann NY Acad Sci. 2010;1191:62–88. https ://doi.org/10.11 ference during novel-word learning. J Exp Psychol Learn Mem Cogn. 11/j.1749-6632.2010.05444 .x. 2009;35:829–35. https ://doi.org/10.1037/a0015 275. 141. Hu X, Ackermann H, Martin JA, Erb M, Winkler S, Reiterer SM. Language 160. Keshavarz MH, Astaneh H. The impact of bilinguality on the learning of aptitude for pronunciation in advanced second language (L2) learners: English vocabulary as a foreign language (L3). Int J Biling Educ Biling. behavioural predictors and neural substrates. Brain Lang. 2013;127:366– 2004;7:295–302. https ://doi.org/10.1080/13670 05040 86678 14. 76. https ://doi.org/10.1016/j.bandl .2012.11.006. 161. Hirosh Z, Degani T. Direct and indirect effects of multilingualism on 142. Archila-Suerte P, Woods EA, Chiarello C, Hernandez AE. Neuroanatomi- novel language learning: an integrative review. Psychon Bull Rev. cal profiles of bilingual children. Dev Sci. 2018;21:e12654. https ://doi. 2018;25:892–916. https ://doi.org/10.3758/s1342 3-017-1315-7. org/10.1111/desc.12654 . 162. Cox JG. Explicit instruction, bilingualism, and the older adult learner. 143. Rodriguez SM, Archila-Suerte P, Vaughn KA, Chiarello C, Hernandez Stud Second Lang Acquis. 2017;39:29–58. https ://doi.org/10.1017/ AE. Anterior insular thickness predicts speech sound learning ability S0272 26311 50003 64. in bilinguals. Neuroimage. 2018;165:278–84. https ://doi.org/10.1016/j. 163. Nation R, Mclaughlin B. Novices and experts: an information processing neuro image .2017.10.038. approach to the “good language learner” problem. Appl Psycholinguist. 144. Elmer S, Rgen Hänggi J, Meyer M, Jäncke L. Differential language 1986;7:41–55. https ://doi.org/10.1017/S0142 71640 00071 77. expertise related to white matter architecture in regions subserving 164. Grey S, Sanz C, Morgan-Short K, Ullman MT. Bilingual and monolingual sensory-motor coupling, articulation, and interhemispheric transfer. adults learning an additional language: ERPs reveal differences in Hum Brain Mapp. 2011;32:2064–74. https ://doi.org/10.1002/hbm.21169 syntactic processing. Biling Lang Cogn. 2018;21:970–94. https ://doi. .org/10.1017/S1366 72891 70004 26. 145. Burgaleta M, Sanjuán A, Ventura-Campos N, Sebastian-Galles N, Ávila 165. Bradley KAL, King KE, Hernandez AE. Language experience differenti- C. Bilingualism at the core of the brain. Structural differences between ates prefrontal and subcortical activation of the cognitive control bilinguals and monolinguals revealed by subcortical shape analysis. network in novel word learning. Neuroimage. 2013;67:101–10. https :// Neuroimage. 2016;125:437–45. https ://doi.org/10.1016/j.neuro image doi.org/10.1016/j.neuro image .2012.11.018. .2015.09.073. 166. Cherodath S, Rao C, Midha R, Sumathi TA, Singh NC. A role for putamen 146. Klein D, Zatorre RJ, Milner B, Meyer E, Evans AC. Left putaminal activa- in phonological processing in children. Biling Lang Cogn. 2017;20:318– tion when speaking a second language. Neuroreport. 1994;5:2295–7. 26. https ://doi.org/10.1017/S1366 72891 60006 14. https ://doi.org/10.1097/00001 756-19941 1000-00022 . 167. Tettamanti M, Moro A, Messa C, Moresco RM, Rizzo G, Carpinelli A, et al. 147. Robles SG, Gatignol P, Capelle L, Mitchell MC, Duffau H. The role of Basal ganglia and language: phonology modulates dopaminergic dominant striatum in language: a study using intraoperative electrical release. NeuroReport. 2005;16:397–401. https ://doi.org/10.1097/00001 stimulations. J Neurol Neurosurg Psychiatry. 2005;76:940–6. https ://doi.756-20050 3150-00018 . org/10.1136/jnnp.2004.04594 8. 168. Masoura EV, Gathercole SE. Phonological short-term memory and 148. Gurd JM, Bessell NJ, Bladon RAW, Bamford JM. A case of foreign foreign language learning. Int J Psychol. 1999;34:383–8. https ://doi. accent syndrome, with follow-up clinical, Neuropsychological and org/10.1080/00207 59993 99738 . phonetic descriptions. Neuropsychologia. 1988;26:237–51. https ://doi. 169. Papagno C, Valentine T, Baddeley A. Phonological short-term memory org/10.1016/0028-3932(88)90077 -2. and foreign-language vocabulary learning. J Mem Lang. 1991;30:331– 149. Meschyan G, Hernandez AE. Impact of language proficiency and ortho - 47. https ://doi.org/10.1016/0749-596X(91)90040 -Q. graphic transparency on bilingual word reading: an fMRI investigation. Hayakawa and Marian Behav Brain Funct (2019) 15:6 Page 24 of 24 170. Mechelli A, Crinion JT, Noppeney U, O’Doherty J, Ashburner J, Frackow- 179. Abutalebi J, Canini M, Della Rosa PA, Green DW, Weekes BS. The neu- iak RS, et al. Neurolinguistics: structural plasticity in the bilingual brain. roprotective effects of bilingualism upon the inferior parietal lobule: a Nature. 2004;431:757. https ://doi.org/10.1038/43175 7a. structural neuroimaging study in aging chinese bilinguals. J Neurolin- 171. Abutalebi J, Green D. Bilingual language production: The neurocog- guistics. 2015;33:3–13. https ://doi.org/10.1016/j.jneur oling .2014.09.008. nition of language representation and control. J Neurolinguistics. 180. Olsen RK, Pangelinan MM, Bogulski C, Chakravarty MM, Luk G, Grady 2007;20:242–75. https ://doi.org/10.1016/j.jneur oling .2006.10.003. CL, et al. The effect of lifelong bilingualism on regional grey and white 172. Baddeley A. Working memory: looking back and looking forward. Nat matter volume. Brain Res. 2015;1612:128–39. https ://doi.org/10.1016/j. Rev Neurosci. 2003;4:829–39. https ://doi.org/10.1038/nrn12 01.brain res.2015.02.034. 173. Bunge SA, Hazeltine E, Scanlon MD, Rosen AC, Gabrieli JDE. Disso- 181. Abutalebi J, Canini M, Della Rosa PA, Sheung LP, Green DW, Weekes ciable contributions of prefrontal and parietal cortices to response BS. Bilingualism protects anterior temporal lobe integrity in aging. selection. Neuroimage. 2002;17:1562–71. https ://doi.org/10.1006/ Neurobiol Aging. 2014;35:2126–33. https ://doi.org/10.1016/j.neuro biola nimg.2002.1252. ging.2014.03.010. 174. Lee H, Devlin JT, Shakeshaft C, Stewart LH, Brennan A, Glensman J, 182. García-Pentón L, Pérez Fernández A, Iturria-Medina Y, Gillon-Dowens et al. Anatomical traces of vocabulary acquisition in the adolescent M, Carreiras M. Anatomical connectivity changes in the bilingual brain. brain. J Neurosci. 2007;27:1184–9. https ://doi.org/10.1523/JNEUR Neuroimage. 2014;84:495–504. https ://doi.org/10.1016/j.neuro image OSCI.4442-06.2007. .2013.08.064. 175. Price CJ, Green DW, von Studnitz R. A functional imaging study of 183. Veroude K, Norris D, Shumskaya E, Gullberg M, Indefrey P. Functional translation and language switching. Brain. 1999;122:2221–35. https :// connectivity between brain regions involved in learning words of a doi.org/10.1093/brain /122.12.2221. new language. Brain Lang. 2010;113:21–7. https ://doi.org/10.1016/j. 176. Vigneau M, Beaucousin V, Hervé PY, Duffau H, Crivello F, Houdé O, et al. bandl .2009.12.005. Meta-analyzing left hemisphere language areas: phonology, semantics, 184. Mandonnet E, Nouet A, Gatignol P, Capelle L, Duffau H. Does the left and sentence processing. Neuroimage. 2006;30:1414–32. https ://doi. inferior longitudinal fasciculus play a role in language? A brain stimula- org/10.1016/j.neuro image .2005.11.002. tion study. Brain. 2007;130:623–9. https ://doi.org/10.1093/brain /awl36 1. 177. Grogan AO, Parker Jones T, Ali N, Crinion J, Orabona S, Mechias ML, et al. 185. Stein M, Federspiel A, Koenig T, Wirth M, Strik W, Wiest R, et al. Structural Structural correlates for lexical efficiency and number of languages in plasticity in the language system related to increased second language non-native speakers of English. Neuropsychologia. 2012;50:1347–52. proficiency. Cortex. 2012;48:458–65. https ://doi.org/10.1016/j.corte https ://doi.org/10.1016/j.neuro psych ologi a.2012.02.019. x.2010.10.007. 178. Della Rosa PA, Videsott G, Borsa VM, Canini M, Weekes BS, Franceschini R, et al. A neural interactive location for multilingual talent. 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Consequences of multilingualism for neural architecture

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Consequences of multilingualism for neural architecture

Consequences of multilingualism for neural architecture

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