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Bilingualism at the core of the brain. Structural differences between bilinguals and monolinguals revealed by subcortical shape analysis
... Although the evidence is more scarce for right CN, its activity has also been linked to language switching (Ma et al., 2014) and simultaneous interpretation (Hervais-Adelman et al., 2015). Moreover, bilingualism-induced neuroplastic changes have been shown for the CN bilaterally (e.g,, Burgaleta et al., 2016;DeLuca et al., 2019b;Pliatsikas et al., 2017;Zou et al., 2012). These findings are in line with the notion that the CN, among other cognitive functions, plays an important role in executive functioning in general. ...
... This process would cause CN's structural substrate to return to pre-bilingualism levels in gross volumetric terms, while its enhanced synaptic connectivity has been reorganized towards higher efficiency. The DRM bases this claim on existing evidence of expansion-renormalization of CN volume (Burgaleta et al., 2016;DeLuca et al., 2019b;Pliatsikas et al., 2017;Zou et al., 2012). The increased efficiency resulting from this structural and functional reorganization (in the CN as well as in other cortical and subcortical structures of the language control network) is argued by the DRM to underlie the neuroprotective effects observed in senior bilinguals. ...
... For a long time, the absence of brain volume differences between bilinguals and monolinguals has been interpreted as evidence against bilingualism-induced neuroplastic effects. The DRM account challenges this view based on the evidence of expansion-renormalization of CN volume (Burgaleta et al., 2016;DeLuca et al., 2019b;Pliatsikas et al., 2017;Zou et al., 2012). Importantly, reports providing such evidence also include a longitudinal study showing reductions in the left CN of immersed bilinguals over a three-year span (DeLuca et al., 2019b). ...
This study investigates bilingualism-induced neuroplastic and cognitive-reserve effects in the Caudate Nucleus (CN), a structure believed to support both bilingual language control and domain-general executive functioning. We computed a generalized bilingualism index incorporating several dimensions of bilingual experience in a sample of bilingual young adults and tested whether this index would predict behavioral executive performance (measured using a Flanker task) and volumetric differences in the CN. Moreover, we investigated whether bilingualism mitigates the relationship between CN volume and executive performance, a sign of cognitive reserve. Our results indicate that bilingualism facilitates executive performance and induces an inverted U-shaped neuroplastic trajectory in bilateral CN, consistently with the view that structural increases are replaced by functional improvements as bilingual experience progresses. The emergence of bilingualism-induced cognitive reserve effects in CN further supports the view that bilinguals rely progressively less on the availability of structural resources in the face of increased functional efficiency.
... www.nature.com/scientificreports/ structures are key for language control, especially in experienced bilinguals, and have been shown to be particularly malleable to bilingual experiences 7,[11][12][13][14][15][16][17] . However, the results reported across studies differ significantly, both in terms of the affected structures, but also in terms of the direction of the effects (i.e., expansions vs. contractions) 1 . ...
... Putting this into the context of bilingualism, the DRM suggests that the cognitively challenging task of juggling two languages will also cause local volumetric increases when the individual is first faced with this challenge, which will themselves start reverting to baseline with increased bilingual experience. Indeed, evidence shows increases in the caudate nucleus, a structure central to controlling between language alternatives, in less experienced bilinguals compared to monolinguals, but no effects in other subcortical structures have been reported 7,11 . By contrast, in more experienced bilinguals, the existing evidence mainly shows volumetric increases in other subcortical structures, like the putamen and the globus pallidus, which are more involved in articulatory control 7,23,24 . ...
... Indeed, evidence shows increases in the caudate nucleus, a structure central to controlling between language alternatives, in less experienced bilinguals compared to monolinguals, but no effects in other subcortical structures have been reported 7,11 . By contrast, in more experienced bilinguals, the existing evidence mainly shows volumetric increases in other subcortical structures, like the putamen and the globus pallidus, which are more involved in articulatory control 7,23,24 . This effect may be related to additional demands for language production as experience increases. ...
Bilingualism has been linked to structural adaptations of subcortical brain regions that are important for controlling multiple languages. However, research on the location and extent of these adaptations has yielded variable patterns, especially as far as the subcortical regions are concerned. Existing literature on bilingualism-induced brain restructuring has so far largely overseen evidence from other domains showing that experience-based structural neuroplasticity often triggers non-linear adaptations which follow expansion-renormalisation trajectories. Here we use generalised additive mixed models to investigate the non-linear effects of quantified bilingual experiences on the basal ganglia and the thalamus in a sample of bilinguals with a wide range of bilingual experiences. Our results revealed that volumes of the bilateral caudate nucleus and nucleus accumbens were significantly related to bilingual experiences. Importantly, these followed a non-linear pattern, with increases followed by plateauing in the most experienced bilinguals, suggesting that experience-based volumetric increases are only necessary up to a certain level of bilingual experience. Moreover, the volumes of putamen and thalamus were positively predicted by bilingual experiences. The results offer the first direct evidence that bilingualism, similarly to other cognitively demanding skills, leads to dynamic subcortical structural adaptations which can be nonlinear, in line with expansion-renormalisation models of experience-dependent neuroplasticity.
... In comparison to monolinguals, bilinguals acquiring a non-native language show greater grey matter (GM) volumes in several cortical (and subcortical) areas involved in language control (e.g., Abutalebi & Green, 2016;Berken et al., 2016b;Burgaleta et al., 2016;Della Rosa et al., 2013;Li et al., 2014;Mårtensson et al., 2012;Mechelli et al., 2004;Pliatsi-kas et al., 2014;Zou et al., 2012) (Cummine & Boliek, 2013;Kuhl et al., 2016;Mamiya et al., 2016;Mohades et al., 2012Mohades et al., , 2015Rossi et al., 2017). Traditional factors, such as age of acquisition (AoA) and proficiency, have been shown to play an important role in predicting structural brain adaptations (e.g., Hosoda et al., 2013;Mamiya et al., 2016;Stein et al., 2012). ...
... Thus, resolving competition leads to greater demands on several neurocognitive networks involved in language processing and control, such as the executive functioning system. At least under specific conditions, bilingualism can result in a more fine-tuned executive control system and in structural, functional and chemical brain adaptations (Abutalebi & Green, 2016;Bialystok et al., 2012;Burgaleta et al., 2016;García-Pentón et al., 2014;Mechelli et al., 2004;Pliatsikas et al., 2015Pliatsikas et al., , 2017Pliatsikas et al., , 2021Weekes et al., 2018). All models presented below (reviewed in chronological order) revolve around different aspects of dual language experiences and offer predictions on the ways the brain should adapt to them. ...
... However, in combination with prolonged duration of bilingual exposure, increased intensity would decrease the latency by which adaptations to efficiency in executive control would occur. Indeed, such trends have been seen in participant cohorts in intensive L2 immersion environments when compared to participants with a potentially longer overall duration of use but lower intensity (see for comparison e.g., Burgaleta et al., 2016;Pliatsikas et al., 2017;Stein et al., 2014). Given that the L2 learners are outside of immersion where English has a clear functional, but not wide societal dispersion, even for individuals who report a young English AoA by virtue of early classroom exposure, such a dual language context is not equivalent to the intensity of two languages from a HS context (where both languages are used across familial, social, and other contexts). ...
... In fact, many investigations carried out to date used samples of bilinguals with very distinct characteristics. While some studies only considered simultaneous bilinguals-that is, bilinguals who first learned both languages at the same time (Burgaleta et al., 2016), others only included bilinguals who were not simultaneously exposed to both languages but acquired the second language (L2) early in life (Olulade et al., 2016), or late sequential bilinguals whose age of acquisition (AoA) of L2 was greater than seven (Pliatsikas et al., 2017;Deluca et al., 2019a). Moreover, the age cutoffs for different groups of bilinguals-simultaneous, early or late-are arbitrary and sometimes differ between studies (Mechelli et al., 2004;Ressel et al., 2012;Klein et al., 2014), which adds to the confusion. ...
... Consequently, it has been argued that bilingualism would be better described as a continuum arising from bilingual experience-based factors, since these show when bilingualism starts to influence the system and how it interacts with it (Deluca et al., 2019a). Following up on the criticism on the categorical approach, recent studies have started to investigate the effects of quantified bilingualism on GM structure, reporting effects such as significant correlations between length of L2 immersion and globus pallidus expansions (Pliatsikas et al., 2017), and reshaping of left thalamus and right caudate nucleus volumes and decreases in left middle temporal gyrus as a function of amount of exposure to L2 (Burgaleta et al., 2016). To investigate similar effects, recent studies have looked at how structural changes can be predicted by bilingualism composite "scores" provided by tools such as the Language and Social Background Questionnaire [LSBQ, Anderson et al. (2018)], the Language Experience and Proficiency Questionnaire [LEAP-Q, Kaushanskaya et al. (2020)], and the Language History Questionnaire [LHQ3, Li et al. (2020)], all of which measure bilingualism experience-based factors such as language proficiency, AoA, or frequency of use in different contexts. ...
... Results showed that L2 AoA positively correlated with GM expansions in the left nucleus accumbens and bilateral thalamus, length of L2 immersion predicted reshaping in right caudate nucleus, expansions in right putamen and contractions in bilateral thalamus and nucleus accumbens, and social use also predicted significant expansions in left caudate nucleus, left nucleus accumbens and right thalamus. Other investigations have also found significant relationships between specific aspects of the bilingual experience and GM structure, such as negative correlations between both AoA and current exposure to L2 and GM volume in right IFG (Wei et al., 2015), reductions in left thalamus and right caudate nucleus, but expansions in left middle temporal gyrus, as a function of amount of time listening and speaking the dominant language (Burgaleta et al., 2016), and positive correlations between expansions in right globus pallidus and length of immersion in a country where L2 is dominant (Pliatsikas et al., 2017). Interestingly, another study found accent scores to be significantly correlated with GM volume in left putamen only in sequential bilinguals-the more native-like they sounded, the more left putaminal volume they showed (Berken et al., 2016). ...
Bilingualism has been shown to induce neuroplasticity in the brain, but conflicting evidence regarding its specific effects in grey matter continues to emerge, probably due to methodological differences between studies, as well as approaches that may miss the variability and dynamicity of bilingual experience. In our study, we devised a continuous score of bilingual experiences and we investigated their non-linear effects on regional GM volume in a sample of young healthy participants from an immersive and naturalistic bilingual environment. We focused our analyses on cortical and subcortical regions that had been previously proposed as part of the bilingual speech pipeline and language control network. Our results showed a non-linear relationship between bilingualism score and grey matter volume of the inferior frontal gyrus. We also found linear increases in volumes of putamen and cerebellum as a function of bilingualism score. These results go in line with predictions for immersive and naturalistic bilingual environments with increased intensity and diversity of language use and provide further evidence supporting the dynamicity of bilingualism’s effects on brain structure.
... Highly pro cient bilinguals face new cognitive challenges linked to increased language production and control, which poses greater demands on language monitoring and motor control related to articulation. This explains the ndings of increases in regions implicated in articulatory control and phonological selection in more experienced bilinguals, such as the left putamen 23,25 and globus pallidus 24 . Similarly, more experienced bilinguals have a likely richer vocabulary, which leads to the growing need for lexical selection during production. ...
... Speci cally, bilinguals with longer or more intensive experience had larger putamen volumes than monolinguals 24 , or their less experienced bilingual counterparts 19,25 . However, the laterality of these effects varied, with increases reported in the right 19 , left 25 , and bilateral putamen 24 . Part of the differences with respect to the laterality of the observed effects might stem from variability in phonological transparency of languages the bilingual used, which has been shown to play a role in a previous study 42 . ...
... In accordance to some recent ndings 19 , we did not observe any effects of bilingualism on the volumes of globus pallidus, which has been shown to expand in experienced bilinguals in other studies 24,26 . A possible explanation relates to the fact that participants in our study were predominantly Czech natives who lived in Czechia. ...
Bilingualism has been linked to structural adaptations of subcortical brain regions that are important nodes in controlling of multiple languages. However, research on the location and extent of these adaptations has yielded variable patterns. Existing literature on bilingualism-induced brain adaptations has so far largely overseen evidence from other domains that experience-based structural neuroplasticity often triggers non-linear adaptations which follow expansion-renormalisation trajectories. Here we use generalised additive mixed models (GAMMs) to investigate the non-linear effects of quantified bilingual experiences on the basal ganglia and thalamus in a sample of bilinguals with wide range of bilingual experiences. Our results revealed that volumes of bilateral caudate nuclei and accumbens were positively related to bilingual experiences in a non-linear pattern, with increases followed by decreases, in the most experienced bilinguals, suggesting a return to baseline volume at higher levels of bilingual experience. Moreover, volumes of putamen and thalamus were positively linearly predicted by bilingual experiences. The results offer the first direct evidence that bilingualism, similarly to other cognitively demanding skills, leads to dynamic subcortical structural adaptations which can be nonlinear, in line with expansion-renormalisation models of experience-dependent neuroplasticity.
... In studies having used voxel-based morphometry (VBM), differences have been found in regions including, among others, cerebellum (e.g. Pliatsikas, Johnstone, & Marinis, 2014), left anterior temporal lobe (Abutalebi et al., 2014), anterior cingulate cortex (Abutalebi et al., 2015), left putamen , Heschl's Gyrus (Ressel et al.), left caudate (Zou, Ding, Abutalebi, Shu, & Peng, 2012), caudate nuclei, putamen and thalamus (Burgaleta, Sanjuan, Ventura-Campos, Sebastian-Galles, & Avila, 2016). The diversity in results may arise from differences across studies in one or several out of a large number of confounding variables that also differentiate groups, other than language knowledge per se. ...
... Here, we predicted that multilingual language experience beyond bilingualism, i.e. in individuals who speak 3 languages or more, would be systematically and positively related to the volumes of these two subcortical structures. It is worth noting that two previous studies (Burgaleta et al., 2016;Pliatsikas, DeLuca, Moschopoulou, & Saddy, 2016) have found that the caudate nuclei of bilinguals are relatively larger compared to those of monolinguals. ...
... The caudate nuclei have been shown to play a role in both language control (Crinion et al., 2006;Hervais-Adelman et al., 2015) and cognitive control (Grahn, Parkinson, & Owen, 2008), and have previously been shown to be enlarged in bilinguals vs. monolinguals (Burgaleta et al., 2016;Pliatsikas, DeLuca, Moschopoulou, & Saddy, 2016). Although there is also evidence for a role of the putamen in multilingual control, it may be that the absence of an observed relationship between putaminal structure and LEXP is due to the nature of its role: if, as suggested by Hervais-Adelman and colleagues (2015), the caudate is implicated in managing lexico-semantic sets as a function of task demands (c.f. the adaptive control hypothesis Green & Abutalebi) while the putamen is involved in moment-to-moment suppression enabling the use of the appropriate language, it is conceivable that the number of competing languages does not substantially change the demands on this lower level of control. ...
The multilingual brain implements mechanisms that serve to select the appropriate language as a function of the communicative environment. Engaging these mechanisms on a regular basis appears to have consequences for brain structure and function. Studies have implicated the caudate nuclei as important nodes in polyglot language control processes, and have also shown structural differences in the caudate nuclei in bilingual compared to monolingual populations. However, the majority of published work has focused on the categorical differences between monolingual and bilingual individuals, and little is known about whether these findings extend to multilingual individuals, who have even greater language control demands. In the present paper, we present an analysis of the volume and morphology of the caudate nuclei, putamen, pallidum and thalami in 75 multilingual individuals who speak three or more languages. Volumetric analyses revealed a significant relationship between multilingual experience and right caudate volume, as well as a marginally-significant relationship with left caudate volume. Vertex-wise analyses revealed a significant enlargement of dorsal and anterior portions of the left caudate nucleus, known to have connectivity with executive brain regions, as a function of multilingual expertise. These results suggest that multilingual expertise might exercise a continuous impact on brain structure, and that as additional languages beyond a second are acquired, the additional demands for linguistic and cognitive control result in modifications to brain structures associated with language management processes.
... Bilingual practices have been consistently linked to brain adaptations of areas in the basal ganglia, such as the caudate nucleus, nucleus accumbens, putamen, and globus pallidus (Burgaleta et al., 2016;Hervais-Adelman et al., 2018;Korenar et al., 2022Korenar et al., , 2023aPliatsikas et al., 2017). The basal ganglia likely serve as gate-keepers, orchestrating our responses to external and internal stimuli, including regulation of cognitive control processes in bilinguals (Green & Kroll, 2019). ...
... Our finding of larger volumes of the caudate nucleus and putamen in professional bilinguals relative to highly experienced bilinguals is consistent with the view that increased and sustained language control demands can result in larger grey matter volumes in the basal ganglia (Burgaleta et al., 2016;Pliatsikas et al., 2017). In this view, larger caudate and putamen volumes in interpreters and translators compared to highly experienced bilinguals would reflect increased demands for control of two languages related to their professions. ...
It remains an open question how the brain adapts structurally to handle strenuous cognitive challenges. Interpreters and translators rely on high cognitive control to regulate two languages in their jobs, which makes them ideal models in investigating experience-based neuroplasticity induced by exceptional cognitive demands. Using structural MRI, we compare volumes of the caudate nucleus and putamen, structures involved in bilingual language control, in three groups of highly experienced bilinguals: translators, interpreters and highly experienced bilinguals. Between-group comparisons revealed larger volumes for both structures in interpreters and translators compared to highly experienced bilinguals. We used Bayesian Generalized Additive Mixed Models to model effects of quantified general bilingual experiences on the structures of interest. Critically, dynamic, group-specific volumetric trajectories of the ROIs related to general bilingual experiences were revealed. Specifically, whereas caudate volumes increased as a function of bilingual experiences across all groups, they started to return to baseline volumes at the high points of experiences in the two professional groups only. As for the putamen, the expansion-renormalisation pattern was replicated in interpreters only, whereas in translators and highly experienced controls, putamen volumes simply increased as a function of bilingual experiences. This pattern of results suggests that bilingualism-related brain adaptations manifest differently in different brain regions and are modulated by quantitative and qualitative differences in bilingual experiences. These findings shed new light on the ways in which extremely demanding bilingual experiences affect neuroplasticity in bilinguals.
... Multiple fMRI studies have further shown a role of the CN in multiple aspects of language including language control, sequence learning, and procedural learning (Ullman, 2001(Ullman, , 2004. The structure of the PU has been shown to expand or increase in GM density with L2 experience Burgaleta, Sanjuán, Ventura-Campos, Sebastian-Galles, & Ávila, 2016) and is involved in articulatory processing and detecting phonological errors Frenck-Mestre, Anton, Roth, Vaid, & Viallet, 2005;Houk, 2005). ...
... Functional MRI and PET studies have demonstrated the putamen's involvement in language production and processing, including articulatory planning and processing (Bohland & Guenther, 2006;Chan et al., 2008;Klein, Zatorre, Milner, Meyer, & Evans, 1994) and detecting phonological errors (Houk, 2005). Our studies are in line with recent literature finding regarding increased GM density or greater expansion in the putamen for multilinguals as compared to monolinguals Burgaleta et al., 2016;Green, Crinion, & Price, 2006). Our findings are also consistent with previous findings associating GMV in the left putamen with late L2 learning performance (Abutalebi et al.2013). ...
Recent research indicates that learning a second language (L2) results in both functional and structural brain changes. However, few studies have examined whether structural brain changes vary as a function of the context in which L2 learning takes place. The current study examines changes in cortical thickness (CT) and gray matter volume (GMV) in response to short-term L2 vocabulary learning. In particular, we compared structural changes for learning with paired picture-word (PW) association versus learning within virtual environments (VE) and non-trained controls. Both L2 training groups learned the same 90 Mandarin Chinese nouns across 7 training sessions over approximately 20 days. Our results show (a) CT and GMV increased in regions implicated in a language control network for both L2 training groups, and (b) participants in different learning contexts may rely on different structures within this language control network. In particular, CT in the right IFG was associated with L2 training performance for the PW group, whereas CT in the right IPL showed a positive correlation with L2 training performance for the VE group. Our findings indicate that short-term L2 training leads to changes in brain structure, which vary based on L2 learning contexts and individual differences in cognitive ability.
... Accumulating evidence supports the advantages of bilingualism for brain structure and function. For instance, neuroanatomical research indicates subcortical morphological differences (Burgaleta, Sanjuan, Ventura-Campos, Sebastian-Galles & Avila, 2016;Pliatsikas, DeLuca, Moschopoulou & Saddy, 2017), larger gray matter volume in language-related brain regions (Abutalebi & Green, 2016;Burgaleta et al., 2016;Del Maschio, Fedeli, Sulpizio & Abutalebi, 2019;Grundy et al., 2017;Mårtensson et al., 2012), and enhanced white matter integrity in the superior longitudinal fasciculus (which connects frontal and parietal components of the executive control network) (Gold, 2015) and the corpus callosum (Bubbico et al., 2019;Kim et al., 2019;Luk, Anderson, Craik, Grady & Bialystok, 2010) in bilinguals relative to monolinguals. Behavioral evidence also underscores the advantages of lifelong bilingualism for executive functions (Adesope, Lavin, Thompson & Ungerleider, 2010;Costa, Hernández & Sebastián-Gallés, 2008;Grundy, 2020;Stocco & Prat, 2014). ...
... Accumulating evidence supports the advantages of bilingualism for brain structure and function. For instance, neuroanatomical research indicates subcortical morphological differences (Burgaleta, Sanjuan, Ventura-Campos, Sebastian-Galles & Avila, 2016;Pliatsikas, DeLuca, Moschopoulou & Saddy, 2017), larger gray matter volume in language-related brain regions (Abutalebi & Green, 2016;Burgaleta et al., 2016;Del Maschio, Fedeli, Sulpizio & Abutalebi, 2019;Grundy et al., 2017;Mårtensson et al., 2012), and enhanced white matter integrity in the superior longitudinal fasciculus (which connects frontal and parietal components of the executive control network) (Gold, 2015) and the corpus callosum (Bubbico et al., 2019;Kim et al., 2019;Luk, Anderson, Craik, Grady & Bialystok, 2010) in bilinguals relative to monolinguals. Behavioral evidence also underscores the advantages of lifelong bilingualism for executive functions (Adesope, Lavin, Thompson & Ungerleider, 2010;Costa, Hernández & Sebastián-Gallés, 2008;Grundy, 2020;Stocco & Prat, 2014). ...
Whereas growing evidence supports the advantages of bilingualism for brain structure and function, no study has shown multilingual-related neuroplasticity in response to speech stimuli at the subcortical level. To investigate the impact of multilingualism on subcortical auditory processing, the speech auditory evoked response (speech-ABR) was recorded on 35 young adults. The multilingual group completed the language experience and proficiency questionnaire (LEAP-Q). The results were that multilingual participants demonstrated evidence of enhanced neural timing processing, including a shorter wave D latency and the V-A duration, and a sharper V-A slope compared to the monolinguals in silence. In the noise condition, the speech-ABR measures degraded in most components, and no significant difference was observed between the two groups. The association between the total proficiency score and several subcortical responses was significant. This shows subcortical evidence of stronger neural synchronization in multilinguals relative to monolinguals, correlated with the self-report of multilingual experience.
... For instance, extensive behavioral evidence indicates the benefits of long-term bilingualism for executive functions. [2][3][4][5][6] Neuroanatomical studies also show larger gray matter volume in language-related brain regions, [7][8][9][10][11] morphological differences in subcortical regions, 8,12 and increased white matter integrity in the superior longitudinal fasciculus (which connects frontal and parietal components of the executive control network) 13 and the corpus callosum [14][15][16] in bilinguals relative to monolinguals. These studies support bilingualism as a potent source of cognitive reserve, which can modulate brain structure and function, enhance cognitive performance, and delay the onset of cognitive decline and dementia. ...
... For instance, extensive behavioral evidence indicates the benefits of long-term bilingualism for executive functions. [2][3][4][5][6] Neuroanatomical studies also show larger gray matter volume in language-related brain regions, [7][8][9][10][11] morphological differences in subcortical regions, 8,12 and increased white matter integrity in the superior longitudinal fasciculus (which connects frontal and parietal components of the executive control network) 13 and the corpus callosum [14][15][16] in bilinguals relative to monolinguals. These studies support bilingualism as a potent source of cognitive reserve, which can modulate brain structure and function, enhance cognitive performance, and delay the onset of cognitive decline and dementia. ...
The past decade marked the beginning of the use of resting‐state functional connectivity (RSFC) imaging in bilingualism studies. This paper intends to review the latest evidence of changes in RSFC in language and cognitive control networks in bilinguals during adulthood, aging, and early Alzheimer's disease, which can add to our understanding of brain functional reshaping in the context of second language (L2) acquisition. Because of high variability in bilingual experience, recent studies mostly focus on the role of the main aspects of bilingual experience (age of acquisition (AoA), language proficiency, and language usage) on intrinsic functional connectivity (FC). Existing evidence accounts for stronger FC in simultaneous rather than sequential bilinguals in language and control networks, and the modulation of the AoA impact by language proficiency and usage. Studies on older bilingual adults show stronger FC in language and frontoparietal networks and preserved FC in posterior brain regions, which can protect the brain against cognitive decline and neurodegenerative processes. Altered RSFC in language and control networks subsequent to L2 training programs also is associated with improved global cognition in older adults. This review ends with a brief discussion of potential confounding factors in bilingualism research and conclusions and suggestions for future research.
... After all, bilingualism requires greater and more sustained efficiency in brain regions subserving language and cognitive control, such as the anterior cingulate gyrus (ACC) and parts of the basal ganglia such as the caudate nucleus and putamen. In fact, all these regions have been shown to change in shape and/or volume as a response to bilingualism 27,[40][41][42][43] . Therefore, it is possible that these structural changes might have their correlates in changes in metabolite concentrations. ...
... The present study expands on Weekes et al. 44 by looking at the effects of bilingualism on metabolite concentrations in the basal ganglia, specifically the caudate nucleus and the putamen. These are key structures for language selection and cognitive control 27 shown to be affected structurally by bilingualism 40,42 . In order to study such effects across the adult lifespan, the present study comprises a relatively large sample that spans an age range representative of the adult lifespan, additionally accounting for the known effects of age on metabolite concentrations 17 . ...
Cognitively demanding experiences, including complex skill acquisition and processing, have been shown to induce brain adaptations, at least at the macroscopic level, e.g. on brain volume and/or functional connectivity. However, the neurobiological bases of these adaptations, including at the cellular level, are unclear and understudied. Here we use bilingualism as a case study to investigate the metabolic correlates of experience-based brain adaptations. We employ Magnetic Resonance Spectroscopy to measure metabolite concentrations in the basal ganglia, a region critical to language control which is reshaped by bilingualism. Our results show increased myo-Inositol and decreased N-acetyl aspartate concentrations in bilinguals compared to monolinguals. Both metabolites are linked to synaptic pruning, a process underlying experience-based brain restructuring. Interestingly, both concentrations correlate with relative amount of bilingual engagement. This suggests that degree of long-term cognitive experiences matters at the level of metabolic concentrations, which might accompany, if not drive, macroscopic brain adaptations.
... These regions primary include: frontal and nearby cortex, including the three portions of the left inferior frontal gyrus (IFG), namely, opercularis (IFGop), triangularis (IFGtr), and orbitalis (IFGor), as well as the frontal pole, the middle and superior frontal gyri (MFG and SFG), and the anterior cingulate cortex (ACC); temporal cortex, including the superior, middle, and inferior temporal gyri (STG, MTG and ITG), Heschl's gyrus, the temporal pole, and the hippocampus; and parietal cortex, including the supramarginal gyrus, the angular gyrus, and the superior parietal lobule (Mechelli et al. 2004;Mårtensson et al. 2012;Abutalebi et al. 2014a;Klein et al. 2014;Stein et al. 2014;Kaiser et al. 2015;Olulade et al. 2016;Hämäläinen et al. 2018). Subcortical structures that are affected mainly include the basal ganglia, in particular the caudate nucleus, the putamen, and the globus pallidus, as well as the thalamus (Burgaleta et al. 2016;Pliatsikas et al. 2017;DeLuca et al. 2019a), with some effects also having been reported in the cerebellum (Filippi et al. 2011(Filippi et al. , 2020Pliatsikas et al. 2014). Moreover, several white matter tracts that provide connectivity between these structures (among others) have also been found to be modified by bilingualism. ...
... In contrast, young adult bilinguals with limited L2 experience often show limited or no changes in subcortical volumes (Pliatsikas et al. 2017). Rather, subcortical differences seem to be found in more experienced bilinguals (in particular, those with substantial L2 immersion, or in bilingual environments), who show greater volumes than monolinguals in a variety of subcortical structures, especially in the basal ganglia (in the caudate, putamen, and globus pallidus), as well as the thalamus and the cerebellum (Burgaleta et al. 2016;Pliatsikas et al. 2017;DeLuca et al. 2019b). Similarly, white matter effects have not been reported in young adults with limited L2 experience. ...
Bilingualism affects the structure of the brain in adults, as evidenced by experience-dependent grey and white matter changes in brain structures implicated in language learning, processing, and control. However, limited evidence exists on how bilingualism may influence brain development. We examined the developmental patterns of both grey and white matter structures in a cross-sectional study of a large sample (n = 711 for grey matter, n = 637 for white matter) of bilingual and monolingual participants, aged 3–21 years. Metrics of grey matter (thickness, volume, and surface area) and white matter (fractional anisotropy and mean diffusivity) were examined across 41 cortical and subcortical brain structures and 20 tracts, respectively. We used generalized additive modelling to analyze whether, how, and where the developmental trajectories of bilinguals and monolinguals might differ. Bilingual and monolingual participants manifested distinct developmental trajectories in both grey and white matter structures. As compared to monolinguals, bilinguals showed: (a) more grey matter (less developmental loss) starting during late childhood and adolescence, mainly in frontal and parietal regions (particularly in the inferior frontal gyrus pars opercularis, superior frontal cortex, inferior and superior parietal cortex, and precuneus); and (b) higher white matter integrity (greater developmental increase) starting during mid-late adolescence, specifically in striatal–inferior frontal fibers. The data suggest that there may be a developmental basis to the well-documented structural differences in the brain between bilingual and monolingual adults.
... These WM adaptations reflect greater integrity and better communication amongst various regions of the brain implicated in language processing. Additionally, volumetric increases in several subcortical structures such as the caudate nucleus, putamen, thalamus and globus pallidus, which have been proposed to be part of Green and Abutalebi's (2013) language control network have also been identified in individuals who acquired both their languages concurrently (Pliatsikas et al., 2017;Berken et al., 2016;Burgaleta et al., 2016). ...
In our increasingly multilingual modern world, understanding how languages beyond the first are acquired and processed at a brain level is essential to design evidence-based teaching, clinical interventions and language policy. Written by a team of world-leading experts in a wide range of disciplines within cognitive science, this Handbook provides a comprehensive overview of the study of third (and more) language acquisition and processing. It features 30 approachable chapters covering topics such as multilingual language acquisition, education, language maintenance and language loss, multilingual code-switching, ageing in the multilingual brain, and many more. Each chapter provides an accessible overview of the state of the art in its topic, while offering comprehensive access to the specialized literature, through carefully curated citations. It also serves as a methodological resource for researchers in the field, offering chapters on methods such as case studies, corpora, artificial language systems or statistical modelling of multilingual data.
... Available work is largely consistent with the claim that continuous juggling of two (or more) languages in the brain engages neural networks involved in domain general cognitive control, especially those that overlap with language control. Research has consistently shown that dual language use, at least past a certain threshold of experience, impacts cortical (Abutalebi, Della Rosa, Green, Hernandez, Scifo, Keim, Cappa & Costa, 2012;Mechelli, Crinion, Noppeney, O'Doherty, Ashburner, Frackowiak & Price, 2004;Pereira Soares, Ong, Abutalebi, Del Maschio, Sewell & Weekes, 2019;Pliatsikas, Johnstone & Marinis, 2014;Stein, Federspiel, Koenig, Wirth, Strik, Wiest, Brandeis & Dierks, 2012) and subcortical/basal ganglia (Burgaleta, Sanjuán, Ventura-Campos, Sebastian-Galles & Ávila, 2016;Pliatsikas, DeLuca, Moschopoulou & Saddy, 2017;Zou, Ding, Abutalebi, Shu & Peng, 2012), white matter tracts (Kuhl, Stevenson, Corrigan, van den Bosch, Can & Richards, 2016;Mohades, Van Schuerbeek, Rosseel, Van De Craen, Luypaert & Baeken, 2015;Rossi, Cheng, Kroll, Diaz & Newman, 2017), functional adaptations (Luk, Anderson, Craik, Grady & Bialystok, 2010;Olulade, Jamal, Koo, Perfetti, LaSasso & Eden, 2015;Rossi, Newman, Kroll & Diaz, 2018), resting state functional connectivity (e.g., Grady, Luk, Craik & Bialystok, 2015;Luk, Green, Abutalebi & Grady, 2012;Rodríguez-Pujadas, Sanjuán, Ventura-Campos, Román, Martin, Barceló, Costa & Ávila, 2013) and even the chemical composition of the brain (Pliatsikas, Pereira Soares, Voits, DeLuca & Rothman, 2021;Weekes, Abutalebi, Mak, Borsa, Pereira Soares, Chiu & Zhang, 2018). These neuroimaging findings have been fairly consistent across studies (see Pliatsikas, 2020;Zhang, Wu & Thierry, 2020 for recent reviews). ...
The study of the brains’ oscillatory activity has been a standard technique to gain insights into human neurocognition for a relatively long time. However, as a complementary analysis to ERPs, only very recently has it been utilized to study bilingualism and its neural underpinnings. Here, we provide a theoretical and methodological starter for scientists in the (psycho)linguistics and neurocognition of bilingualism field(s) to understand the bases and applications of this analytical tool. Towards this goal, we provide a description of the characteristics of the human neural (and its oscillatory) signal, followed by an in-depth description of various types of EEG oscillatory analyses, supplemented by figures and relevant examples. We then utilize the scant, yet emergent, literature on neural oscillations and bilingualism to highlight the potential of how analyzing neural oscillations can advance our understanding of the (psycho)linguistic and neurocognitive understanding of bilingualism.
... Experiences, such as language experience and musical training, may also shape the way the nervous system responds to sensory input and the subcortical pitch information encoding ability. The brain undergoes widespread neural specialization relating to language and cognitive processing (Costa and Sebastián-Gallés, 2014;Burgaleta et al., 2016). At the subcortical level, pitch processing of lexical tones can be shaped by language experience in both childhood and adulthood (Li et al., 2001;Wang et al., 2004;Liu et al., 2020). ...
Aging and language background have been shown to affect pitch information encoding at the subcortical level. To study the individual and compounded effects on subcortical pitch information encoding, Frequency Following Responses were recorded from subjects across various ages and language backgrounds. Differences were found in pitch information encoding strength and accuracy among the groups, indicating that language experience and aging affect accuracy and magnitude of pitch information encoding ability at the subcortical level. Moreover, stronger effects of aging were seen in the magnitude of phase-locking in the native language speaker groups, while language background appears to have more impact on the accuracy of pitch tracking in older adult groups.
... Friederici (Jeon et al. 2014, Kotz et al. 2002, Mestres-Misse et al. 2012, Wahl et al. 2008 and Peter Hagoort (Snijders et al. 2010). While the notion that subcortical structures contribute to language remains, in our view, a minority position, there are nevertheless a range of researchers who appear to be converging on the view that subcortex is recruited for language; for instance, in bilingualism (Bice et al. 2020, Burgaleta et al. 2016, Cargnelutti et al. 2019, Hervais-Adelman et al. 2018, Stocco et al. 2014, phonological processing (Booth et al. 2007), syntax (Lieberman 2006(Lieberman , 2015, reading (Braun et al. 2019, Yeatman & White 2021, word learning (Takashima et al. (2014) and lexical access (Crinion et al. 2013, Hernandez & Li 2007, Meinzer et al. 2006). Our aim is not to label various models as subcortical-inclusive or subcorticalexclusive, but to evaluate the apparent roles of subcortical structures in higher-order language processing, with particular emphasis on brain dynamics. ...
... This is particularly true when attempting to differentiate specific language competencies within each network. In recent years, bilingualism researchers have instead turned their attention to characterization of the language control network in bilinguals (Hernández, Costa, Fuentes, Vivas, & Sebastián-Gallés, 2010;Pliatsikas, & Luk, 2016;Rodriguez-Fornells, De Diego Balaguer, & Münte, 2006), structural magnetic resonance imaging (MRI) studies (Abutalebi, Canini, Della Rosa, Green, & Weekes, 2015;Burgaleta, Sanjuán, Ventura-Campos, Sebastian-Galles, & Ávila, 2016;Kuhl, Stevenson, Corrigan, van den Bosch, Can, & Richards, 2016), and connectivity research (Berken, Chai, Chen, Gracco, & Klein, 2016;Sulpizio, Del Maschio, Del Mauro, Fedeli, & Abutalebi, 2020;Zou, Abutalebi, Zinszer, Yan, Shu, Peng, & Ding, 2012). While these studies foreground important research questions in their own right, the shift in the literature reflects a growing frustration with our abilities to discern potentially fine-grained differences between L1 and L2 processing by means of univariate fMRI analyses. ...
The functional organization of first (L1) and second (L2) language processing in bilinguals remains a topic of great interest to the neurolinguistics community. Functional magnetic resonance imaging (fMRI) studies report meaningful differences in the location and extent of hemodynamic changes between tasks performed in the L1 and L2, yet there is no consensus on whether these networks can be considered truly distinct. In part, this may be due to the multiplicity of task designs implemented in such studies, which complicates the interpretation of their findings. This paper compares the results of previous bilingual meta-analyses to a new ALE meta-analysis that categorizes neuroimaging studies by task design. Factors such as the age of L2 acquisition (AoA) and the L2 language proficiency level of participants are also considered. The findings support previous accounts of the effect of participant characteristics on linguistic processing, while at the same time revealing dissociable differences in fMRI activation for L1 and L2 networks within and across tasks that appear independent of these external factors.
... Consistent with this idea, recent evidence has suggested that bilingualism reshapes the basal ganglia. Burgaleta et al. (2016), for example, showed that relative to monolinguals, bilinguals had expanded surface area in several subcortical nuclei, including the caudate, accumbens, putamen, globus pallidus, and thalamus. These findings were echoed by Pliatsikas et al. (2017), who further showed that degree of second language immersion correlated with subcortical tissue expansion particularly in the globus pallidus in sequential bilinguals. ...
This study compared brain and behavioral outcomes for monolingual and bilingual older adults who reported no cognitive or memory problems on three types of memory that typically decline in older age, namely, working memory (measured by n-back), item, and associative recognition. The results showed that bilinguals were faster on the two-back working memory task than monolinguals but used a set of frontostriatal regions less than monolinguals. There was no group difference on an item/associative recognition task. In brain structure, gray matter volume and white matter integrity (fractional anisotropy) were generally lower in bilinguals than in monolinguals, but bilinguals had better white matter integrity than monolinguals in the bilateral superior corona radiata and better gray matter density in the left inferior temporal gyrus. These regions may help preserve bilinguals’ executive functions despite generally more significant atrophy throughout the brain than monolinguals in that these structures contribute to efficient communication between executive frontal regions and subcortical motor regions, and perceptual pathways. Reliable negative correlations between brain structure and age were only observed in bilinguals, and to the extent that bilinguals (but not monolinguals) had better brain structure, their performance was enhanced. Collectively, the findings provide evidence for reserve in bilingual older adults.
... Currently, it is largely agreed through structural and functional imaging studies that learning a second language elicits several gray and white matter neuroanatomical changes, and that the acquisition and use of a second language results in experiencedependent structural plasticity and macro-anatomical changes independent to those of monolinguals (Burgaleta et al., 2016). ...
In recent years, there has been a rise in the number of people who are able to speak two or more languages. This has been paralleled by an increase in research related to bilingualism. Despite this, much of the neuroanatomical consequences and patho- logical implications of bilingualism are still subject to discussion. This review aims to evaluate the neuroanatomical structures related to language and to the acquisition of a second language as well as exploring how learning a second language can alter one's susceptibility to and the progression of certain cerebral pathologies. A literature search was conducted on the Medline, Embase, and Web of Science databases. A total of 137 articles regarding the neuroanatomical or pathological implications of bilingual- ism were included for review. Following analysis of the included papers, this review finds that bilingualism induces significant gray and white matter cerebral changes, particularly in the frontal lobes, anterior cingulate cortex, left inferior parietal lobule and subcortical areas, and that native language and acquired language largely recruit the same neuroanatomical structures with however, subtle functional and anatomi- cal differences dependent on proficiency and age of language acquisition. There is adequate evidence to suggest that bilingualism offsets the symptoms and diagnosis of dementia, and that it is protective against both pathological and age-related cognitive decline. While many of the neuroanatomical changes are known, more remains to be elucidated and the relationship between bilingualism and other neurological patholo- gies remains unclear.
... A recent neuroimaging study(Mitsuhashi et al., 2020) applying fMRI and DWI tractography to clarify the mechanisms of neural plasticity involved in language found increased fiber counts in right precentral gyrus in early bilingual acquisition, suggesting the increased neural connections between right precentral gyrus to right basal ganglia may be a key pattern of neural plasticity in language skills. Volumetric analyses(Burgaleta, Sanju an, Ventura-Campos, Sebastian- Galles, & Avila, 2016;Hervais-Adelman, Egorova, & Golestani, 2018) also revealed a significant relationship between multilingual experience and right caudate volume, as well as a marginally significant relationship with left caudate volume, suggesting right caudate as a key hub for language acquisition. Similarly, the left angular gyrus was suggested to be a key part of the perisylvian language network ...
This study investigated whether current state-of-the-art deep reasoning network analysis on psychometry-driven diffusion tractography connectome can accurately predict expressive and receptive language scores in a cohort of young children with persistent language concerns (n = 31, age: 4.25 ± 2.38 years). A dilated convolutional neural network combined with a relational network (dilated CNN + RN) was trained to reason the nonlinear relationship between "dilated CNN features of language network" and "clinically acquired language score". Three-fold cross-validation was then used to compare the Pearson correlation and mean absolute error (MAE) between dilated CNN + RN-predicted and actual language scores. The dilated CNN + RN outperformed other methods providing the most significant correlation between predicted and actual scores (i.e., Pearson's R/p-value: 1.00/<.001 and .99/<.001 for expressive and receptive language scores, respectively) and yielding MAE: 0.28 and 0.28 for the same scores. The strength of the relationship suggests elevated probability in the prediction of both expressive and receptive language scores (i.e., 1.00 and 1.00, respectively). Specifically, sparse connectivity not only within the right precentral gyrus but also involving the right caudate had the strongest relationship between deficit in both the expressive and receptive language domains. Subsequent subgroup analyses inferred that the effectiveness of the dilated CNN + RN-based prediction of language score(s) was independent of time interval (between MRI and language assessment) and age of MRI, suggesting that the dilated CNN + RN using psychometry-driven diffusion tractography connectome may be useful for prediction of the presence of language disorder, and possibly provide a better understanding of the neurological mechanisms of language deficits in young children.
... The peak voxel in our data is slightly more medial in the pallidum.) They argued that this pattern reflects bilinguals' greater reliance on articulatory motor Bilingualism: Language and Cognition 533 processes in mapping novel and existing words, given the known involvement of the putamen/pallidum in motor processes and control of articulatory processes (e.g., Wildgruber, Ackermann & Grodd, 2001;Wise, Greene, Buchel & Scott, 1999; for review, see Viñas-Guasch & Wu, 2017), and the finding of increased grey matter density in the left putamen for multilinguals relative to monolinguals (Abutalebi et al., 2013; see also Burgaleta, Sanjuán, Ventura-Campos, Sebastián-Gallás & Ávila, 2016). If bilinguals' long-term experience navigating two languages and controlling articulatory processes in two languages induced structural changes in the putamen and has prepared bilinguals to rely on articulatory motor processing when integrating novel words into their existing mental lexicon, then this may also explain why a bilingual advantage in word learning is prevalent in behavioural studies employing auditory or combined auditory-visual word learning strategies, and why studies using visual-only learning strategies (the present study and Bradley et al., 2013) did not observe a bilingual advantage. ...
This study investigated how bilingual experience alters neural mechanisms supporting novel word learning. We hypothesised that novel words elicit increased semantic activation in the larger bilingual lexicon, potentially stimulating stronger memory integration than in monolinguals. English monolinguals and Spanish–English bilinguals were trained on two sets of written Swahili–English word pairs, one set on each of two consecutive days, and performed a recognition task in the MRI-scanner. Lexical integration was measured through visual primed lexical decision. Surprisingly, no group difference emerged in explicit word memory, and priming occurred only in the monolingual group. This difference in lexical integration may indicate an increased need for slow neocortical interleaving of old and new information in the denser bilingual lexicon. The fMRI data were consistent with increased use of cognitive control networks in monolinguals and of articulatory motor processes in bilinguals, providing further evidence for experience-induced neural changes: monolinguals and bilinguals reached largely comparable behavioural performance levels in novel word learning, but did so by recruiting partially overlapping but non-identical neural systems to acquire novel words.
... Also importantly, other investigations suggest that the thalamus is related to language processing and bilingualism, based on evidence showing that corticothalamo-cortical connections have a pivotal impact on language processing through feedback mechanisms (Crosson, 2013) and that the thalamus is expanded in young simultaneous bilinguals compared with monolinguals (Burgaleta et al., 2016). Thus, our results suggest that bilingualism may act as a CR factor by means of a higher amplitude of regional spontaneous activity in the thalamus, specifically in nuclei that show atrophy in dementia (Zarei et al., 2010) and are related to memory impairment (Danet et al., 2017;Fedio and Van Buren, 1975;Harding et al., 2000). ...
Background:
Bilingualism is considered a cognitive reserve (CR) factor, due to the delay in the onset of dementia in bilinguals compared to monolinguals. Two neural mechanisms have been suggested to underlie CR: neural reserve and neural compensation. However, it is still unclear how bilingualism contributes to these mechanisms.
Methods:
In this study, we used cognitive tests, functional connectivity (FC), regional homogeneity, and fractional amplitude of low-frequency fluctuation (fALFF) measures to study resting-state brain patterns in a sample of bilingual and monolingual subjects with mild cognitive impairment (MCI).
Results:
We found no significant differences between the groups in age, sex, education, or cognitive level, but bilinguals showed higher FC than monolinguals between the posterior part of the superior temporal gyrus and the precuneus, positively correlated with Mini-Mental State Examination (MMSE) scores, and higher fALFF in the thalamus bilaterally.
Conclusions:
Our results suggest that bilingualism may act as a CR factor that protects against dementia through neural compensation.
... Then, as dual-language management becomes more automatic, its neural processing shifts partly to subcortical areas (Lieberman, 2000;Tettamanti et al., 2005) as occurs in procedural knowledge (Packard and Knowlton, 2002). Bilinguals show expanded morphology in basal ganglia (Burgaleta et al., 2016). Damage to this brain area produces pathologic code-switching (Lieberman, 2000;Abutalebi and Green, 2008) similarly as it affects task-switching abilities in early Parkinson disease patients (Packard and Knowlton, 2002). ...
Findings suggest a positive impact of bilingualism on cognition, including the later onset of dementia. However, it is not clear to what extent these effects are influenced by variations in attentional control demands in response to specific task requirements. In this study, 20 bilingual and 20 monolingual older adults performed a task-switching task under explicit task-cuing vs. memory-based switching conditions. In the cued condition, task switches occurred in random order and a visual cue signaled the next task to be performed. In the memory-based condition, the task alternated after every second trial in a predictable sequence without presenting a cue. The performance of bilinguals did not vary across experimental conditions, whereas monolinguals experienced a pronounced increase in response latencies and error rates in the cued condition. Both groups produced similar switch costs (difference in performance on switch trials as opposed to repeating trials within the mixed-task block) and mixing costs (difference in performance on repeat trials of a mixed-task block as opposed to trials of a single-task block), but bilinguals produced them with lower response latencies. The cognitive benefits of bilingualism seem not to apply to executive functions per se but to affect specific cognitive processes that involve task-relevant context processing. The present results suggest that lifelong bilingualism could promote in older adults a flexible adjustment to environmental cues, but only with increased task demands. However, due to the small sample size, the results should be interpreted with caution.
... There is ample literature on neuroplasticity as it relates to bilingualism and second language (L2) learning [1][2][3][4][5]. Learning two languages simultaneously is typically defined as simultaneous bilingualism. ...
Second language learning has been shown to impact and reshape the central nervous system, anatomically and functionally. Most of the studies on second language learning and neuroplasticity have been focused on cortical areas, whereas the subcortical neural encoding mechanism and its relationship with L2 learning have not been examined extensively. The purpose of this study was to utilize frequency-following response (FFR) to examine if and how learning a tonal language in adulthood changes the subcortical neural encoding in hearing adults. Three groups of subjects were recruited: native speakers of Mandarin Chinese (native speakers (NS)), learners of the language (L2 learners), and those with no experience (native speakers of foreign languages (NSFL)). It is hypothesized that differences would exist in FFRs obtained from the three language experience groups. Results revealed that FFRs obtained from L2 learners were found to be more robust than the NSFL group, yet not on a par with the NS group. Such results may suggest that in human adulthood, subcortical neural encoding ability may be trainable with the acquisition of a new language and that neuroplasticity at the brainstem level can indeed be influenced by L2 learning.
... The present study expands on Weekes et al. 45 by looking at the effects of bilingualism on metabolite concentrations in the ventral striatum, a subcortical grey matter nucleus comprising the caudate nucleus and the putamen, key structures for language selection and cognitive control 28 , that have both been shown to be affected structurally by bilingualism 41,43 . In order to study such effects across the adult lifespan, the present study comprises a relatively large sample that spans an age range representative of the adult lifespan, additionally accounting for the known effects of age on metabolite concentrations 19 . ...
Cognitively demanding experiences, including complex skills acquisition and processing, have been shown to induce brain adaptations, at least at the macroscopic level, e.g. on brain volume and/or functional connectivity. However, the neurobiological bases of these adaptations, including at the microstructural cellular level, remain poorly understood. Here we use bilingualism as a case study to investigate the microscopic correlates of experience-based brain adaptations. We employ Magnetic Resonance Spectroscopy to measure concentrations of metabolites in the ventral striatum, a region critical to language control which is reshaped by bilingualism. Our results revealed increased concentration of myo-Inositol in bilinguals compared to monolinguals. This metabolite is linked to synaptic pruning, a process underlying experience-based brain restructuring. Crucially, concentration was predicted by relative amount of bilingual engagement. Our results suggest that (degree of) long-term cognitive experiences have measurable effects at the microcellular level, which might accompany, if not drive, the observed macroscopic brain adaptations.
... The procedure is known as a generalized Procrustes analysis [3]. The shape analysis applications include medical imaging and morphometrics for biology [5][6][7][8][9][10][11]. Although there are many papers on biology and medical imaging fields, as far as we know, there are no economics analysis paper by this statistical shape analysis except [12]. ...
Alzheimer’s disease (AD) is an age-related neurocognitive disorder that is epidemic in the elderly population. Currently, there are limited pharmacological interventions, and this has heightened the urgency to identify potential preventable or modifiable risk factors that promote resilience to the neuropathological effects of AD. The regular use of two or more languages is one such factor that may increases cognitive reserve through the long-standing executive control involved in managing multiple languages in the brain. There is also evidence that bilingualism is associated with increased brain reserve or maintenance, particularly in frontal-executive structures and networks. This review examines the current, sometimes conflicting literature on bi/multilingualism and AD. These studies have confounding variations in the assessment of age of second language onset, language proficiency, language usage, and whether determining incidence of AD or age of symptom onset. Despite these limitations, most publications support the presence of increased frontal-executive reserve that compensates for the development of AD neuropathology and, thereby, delays the emergence of clinical symptoms of dementia by about 4-5 years. Although regularly speaking more than one language does not protect against AD neuropathology, the delay in its clinical expression has a potentially significant impact on the lifelong morbidity from this age-related disease. Learning other languages may be an important modifiable factor for delaying the clinical expression of AD in later life.
Multilingualism affects cognitive, behavioral, and neural function across the lifespan. Here, we review the neuroimaging literature on bilingualism, multilingualism, and executive functions, focusing on three multilingual groups who rely on language control to varying degrees to overcome competition from other languages: third-language learners, multilingual adults, and simultaneous interpreters. In third-language learners, changes in brain regions underlying executive functions occur during the early stages of acquiring another language. In multilingual adults, effects of language experience reflect a qualitative difference between monolingual and multilingual processing rather than cumulative effects of increased linguistic knowledge. In simultaneous interpreters, changes in gray matter volume and white matter integrity are found in areas underlying language selection and executive functions, reflecting neural efficiency due to experience with rapid translation. The implications of these findings for our understanding of multilingualism and the value of moving beyond the monolingual–bilingual dichotomy are discussed.
Structural and functional brain adaptations in bilingual speakers are well documented in the neurolinguistic literature. However, far less is known about neural changes evidenced in multilingual speakers. This study investigates brain plasticity in a group of highly proficient multilinguals, fluent in four or more languages, compared to a group of monolinguals. An ROI analysis used to evaluate differences in core linguistic regions and regions associated with language control revealed robust decreases for multilinguals in grey matter thickness of two brain regions within the parietal lobe (i.e., precuneus and angular gyrus), involved in lexico-semantic processing, memory retrieval, and control maintenance. We discuss our findings in the context of emerging models characterizing trajectorial changes in brain structures associated with language experience. We consider how the demands of optimal functioning within multi-linguistic environments may foster cortical changes that manifest as decreased GM thickness in highly proficient multilingual compared to monolinguals.
Bilingualism is a ubiquitous global phenomenon. Beyond being a language experience, bilingualism also entails a social experience, and it interacts with development and learning, with cognitive and neural consequences across the lifespan. The authors of this volume are world renowned experts across several subdisciplines including linguistics, developmental psychology, and cognitive neuroscience. They bring to light bilingualism’s cognitive, developmental, and neural consequences in children, young adults, and older adults. This book honors Ellen Bialystok, and highlights her profound impact on the field of bilingualism research as a lifelong experience. The chapters are organized into four sections: The first section explores the complexity of the bilingual experience beyond the common characterization of “speaking multiple languages.” The next section showcases Ellen Bialystok’s earlier impact on psychology and education; here the contributors answer the question “how does being bilingual shape children’s development?” The third section explores cognitive and neuroscientific theories describing how language experience modulates cognition, behavior, and brain structures and functions. The final section shifts the focus to the impact of bilingualism on healthy and abnormal aging and asks whether being bilingual can stave off the effects of dementia by conferring a “cognitive reserve.”
Bilingualism is a ubiquitous global phenomenon. Beyond being a language experience, bilingualism also entails a social experience, and it interacts with development and learning, with cognitive and neural consequences across the lifespan. The authors of this volume are world renowned experts across several subdisciplines including linguistics, developmental psychology, and cognitive neuroscience. They bring to light bilingualism’s cognitive, developmental, and neural consequences in children, young adults, and older adults. This book honors Ellen Bialystok, and highlights her profound impact on the field of bilingualism research as a lifelong experience. The chapters are organized into four sections: The first section explores the complexity of the bilingual experience beyond the common characterization of “speaking multiple languages.” The next section showcases Ellen Bialystok’s earlier impact on psychology and education; here the contributors answer the question “how does being bilingual shape children’s development?” The third section explores cognitive and neuroscientific theories describing how language experience modulates cognition, behavior, and brain structures and functions. The final section shifts the focus to the impact of bilingualism on healthy and abnormal aging and asks whether being bilingual can stave off the effects of dementia by conferring a “cognitive reserve.”
Four patterns describe how bilingualism affects the functional connectivity of the brain. First, a general observation across most of the studies I surveyed was that bilinguals tended to have higher functional connectivity when compared to monolinguals. Second, increased connectivity with the salience network, a set of regions including the anterior cingulate cortex, the bilateral insula, and subcortical regions is often associated with language training or language diversity where proactive attention to content is paramount. Third, to the degree that individuals have greater exposure or mastery of a second language, (greater proficiency and an earlier or simultaneous age of acquisition) and can rely more on reactive control, studies often show greater bilateral connectivity between the inferior frontal gyri. This is also sometimes associated with decreased activation of frontal regions implying distributed load and greater neural efficiency. The distributed neural pattern in young adulthood may also explain how bilingual older adults are able to sustain their cognition at levels of neuropathology most monolinguals cannot endure. Fourth, in studies that examined anticorrelations between task and rest networks, bilinguals tended to have more distinct (e.g., modular organization), and more strongly anticorrelated task-positive and default-mode networks, and this was often correlated with cognitive control.
The current paper aims to evaluate the metacognitive awareness of translating of idiomatic expressions. Metacognitive awareness is tested through Cognitive Task Analysis (henceforth CTA) and evaluating competencies to solve the translation problems. It is based on the model analyzing the regulatory and executive functions during the translation process. It is hypothesized that the translators have intrinsic competencies to conceptualize the idiomatic expressions in the SL and TL than in bilinguals depending on their expertise, error-monitoring, and attention-control during translation tasks. To resolve this apparent discrepancy between translators and bilinguals, the current study tackles two subject groups; the first involves (translators), and the second includes bilinguals, they were given question forms of idiomatic expressions. Statistics (G factor) was taken as the procedure of data analysis. The study concludes that translators do not have only potential metalinguistic skills, but a subset of metacognitive awareness to the textual material. Bilinguals, on the other hand, have metalinguistic skills to come up with the patterns of conceptualizing idiomatic expressions.
Purpose. Languages play an important role in shaping our brain and personality. Numerous studies in the past have found that bilingual and trilingual individuals outperform monolinguals on certain cognitive assessments. In some studies, monolinguals have outperformed the other two groups on emotional tests. Most of the studies have reported mixed findings on this topic, making it difficult to draw conclusions.
Procedure. For the first time, the present study attempts to examine linguistic ability, empathy, emotional intelligence and cognitive flexibility in an Indian sample of 90 participants (Mage = 26.86 years, SD = 7.45) (28 monolingual, 30 bilingual and 32 trilingual). Each of the participants completed the Interpersonal Reactivity Index Questionnaire, Trait Emotional Intelligence Questionnaire – Short Form and Colour Stroop Test on PEBL (Psychology Experiment Building Language) software.
Results. One – Way ANOVA revealed statistically significant results for Empathy [F(2,87) = 218.84, p
Diffusion-weighted imaging has been widely used in the research on post-stroke verbal fluency but acquiring diffusion data is not always clinically feasible. Achieving comparable reliability for detecting brain variables associated with verbal fluency impairments, based on more readily available anatomical, non-diffusion images (T1, T2 and FLAIR), enables clinical practitioners to have complementary neurophysiological information at hand to facilitate diagnosis and treatment of language impairment. Meanwhile, although the predominant focus in the stroke recovery literature has been on cortical contributions to verbal fluency, it remains unclear how subcortical regions and white matter disconnection are related to verbal fluency. Our study thus utilized anatomical scans of ischaemic stroke survivors (n = 121) to identify longitudinal relationships between subcortical volume, white matter tract disconnection, and verbal fluency performance at 3- and 12-months post-stroke. Subcortical grey matter volume was derived from FreeSurfer. We used an indirect probabilistic approach to quantify white matter disconnection in terms of disconnection severity, the proportion of lesioned voxel volume to the total volume of a tract, and disconnection probability, the probability of the overlap between the stroke lesion and a tract. These disconnection variables of each subject were identified based on the disconnectome map of the BCBToolkit. Using a linear mixed multiple regression method with 5-fold cross-validations, we correlated the semantic and phonemic fluency scores with longitudinal measurements of subcortical grey matter volume and 22 bilateral white matter tracts, while controlling for demographic variables (age, sex, handedness and education), total brain volume, lesion volume, and cortical thickness. The results showed that the right subcortical grey matter volume was positively correlated with phonemic fluency averaged over 3 months and 12 months. The finding generalized well on the test data. The disconnection probability of left superior longitudinal fasciculus II and left posterior arcuate fasciculus was negatively associated with semantic fluency only on the training data, but the result aligned with our previous study using diffusion scans in the same clinical population. In sum, our results presented evidence that routinely acquired anatomical scans can serve as a reliable source for deriving neural variables of post-stroke verbal fluency performance. The use of this method might provide an ecologically valid and more readily implementable analysis tool.
Meta-analyses are a method by which to increase the statistical power and general-izability of neuroimaging findings. In the neurolinguistics literature, meta-analyses have the potential to substantiate hypotheses about L1 and L2 processing networks and to reveal differences between the two that may escape detection in individual studies. Why then is there so little consensus between the reported findings of even the most recently published and most highly-powered meta-analyses? Limitations in the literature, such as the absence of a common method to define and measure descriptive categories (e.g., proficiency level, degree of language exposure, age of acquisition , etc.) are often cited. An equally plausible explanation lies in the technical details of how individual meta-analyses are conducted. This paper provides a review of recent meta-analyses, with a discussion of their methodological choices and the possible effect those choices may have on the reported findings.
Human communication not only involves the need to switch between the modalities of speaking and listening, but for bilinguals, it can also involve switching between languages. It is unknown as to whether modality and language switching share underlying control mechanisms or whether one type of switching affects control processes involved in the other. The present study uses behavioral and fMRI measures to examine neural circuits of control during communicative situations that required Chinese-English bilinguals to switch between modalities and their two languages according to associated color cues. The results showed that for both language and modality control, similar brain regions were recruited during speech production and comprehension. For modality control, the specific control processes partly depended on the corresponding modality. Finally, switching between modalities appears to exert more influence on language control in production compared to comprehension. These findings offer a first detailed characterization of the neural bases involved in control mechanisms in bilingual communication.
The present study uses EEG time-frequency representations (TFRs) with a Flanker task to investigate if and how individual differences in bilingual language experience modulate neurocognitive outcomes (oscillatory dynamics) in two bilingual group types: late bilinguals (L2 learners) and early bilinguals (heritage speakers—HSs). TFRs were computed for both incongruent and congruent trials. The difference between the two (Flanker effect vis-à-vis cognitive interference) was then (1) compared between the HSs and the L2 learners, (2) modeled as a function of individual differences with bilingual experience within each group separately and (3) probed for its potential (a)symmetry between brain and behavioral data. We found no differences at the behavioral and neural levels for the between-groups comparisons. However, oscillatory dynamics (mainly theta increase and alpha suppression) of inhibition and cognitive control were found to be modulated by individual differences in bilingual language experience, albeit distinctly within each bilingual group. While the results indicate adaptations toward differential brain recruitment in line with bilingual language experience variation overall, this does not manifest uniformly. Rather, earlier versus later onset to bilingualism—the bilingual type—seems to constitute an independent qualifier to how individual differences play out.
Bilingualism imposes additional requirements on the cognitive system. As such, it can be a driving force of neuroplastic changes in the brain of a person who speaks more than one language. The need to store and use two systems of representations corresponding to the two languages as well as to develop an efficient control system which allows to use the intendent, contextual-ly appropriate language, may result in both functional and structural changes. Neuroimaging studies show that the neural organization of language representations in a bilingual brain depends to a large degree on the type of representation. Conceptual representations seem to share common neural underpinnings between the different languages. Lexical representations, related to the vocabulary and words, are processed by the same brain regions regardless of the language, however , they have been shown to be coded by distinct neu-ronal populations. Finally, neuroplastic reorganization of syntactic representations is highly dependent on factors related to individual experiences of bilingualism, such as age of acquisition and proficiency in the second language. Neuroplastic changes in the bilingual brain have also been linked to the increased demands that using two languages imposes on the cognitive control mechanisms. Both structural and functional changes in the brain of bilinguals were observed withing a wide network referred to as language control network. Summing up, neuroimaging studies have demonstrated that bilingualism is related to neuroplastic changes in both structure and functioning of the brain. However, the newest reports suggest the extent and intensity of the neuroplastic changes are most likely dependent on individual experiences of each bilingual speaker.
Subcortical contributions to core linguistic computations pertaining to syntax-semantics remain drastically under-studied. We critique the cortico-centric focus which has largely accompanied research into these higher-order linguistic functions and suggest that, while much remains unknown , there is nevertheless a rich body of research concerning the possible roles of subcortex in natural language. Although much current evidence emerges from distinct domains of cognitive neuroscience, in this review article we attempt to show that there is a clear place for subcortex in models of natural language syntax-semantics, including a role in binary set-formation, categorized object maintenance, lexico-semantic processing, conceptual-to-lexical transformations, morphosyntactic linearization, semantic feature-binding, and cross-cortical representational integration. In particular, we consult models of language processing relying on oscillatory brain dynamics in order to investigate both the apparent and possible functional roles of subcortex in language.
Autism spectrum disorder (ASD) is associated with marked heterogeneity with respect to the development of executive function abilities. The ‘bilingual advantage’ refers to the observation that individuals who speak two languages perform better on executive function tasks than monolinguals under some circumstances. There is not yet consensus, however, as to whether this advantage can be reliably demonstrated, nor is there consensus regarding under which conditions it emerges. Bilingual and monolingual children with ASD have comparable developmental outcomes, particularly in the areas of core ASD symptoms, cognitive function, and language. Still, despite the potential advantages that bilingualism may confer, clinicians commonly advise against providing a bilingual environment for children with ASD. The purpose of the present review is to provide an up-to-date assessment of the limited literature on bilingualism in children with ASD in order to inform evidence-based practice. Studies suggest a potential bilingual advantage in ASD in the areas of nonverbal intelligence quotient, adaptive functioning, and expressive vocabulary. A limited yet growing literature provides preliminary evidence for enhanced executive function ability in some children with ASD. Taken together, current evidence suggests that although a ‘bilingual advantage’ may not be universally present in typical development, it may manifest under specific circumstances, conferring advantage for populations in which executive function is compromised. Further work is needed to develop consistent, evidence-based guidelines around language recommendations for families of children with ASD and to better understand the cognitive and brain mechanisms giving rise to the bilingual advantage in clinical developmental populations.
Being multilingual is a valuable advantage in today’s global society, which is right at everyone’s doorstep. Language and the ability to communicate are important skills to possess. These skills are particularly useful for healthcare professionals because without effective communication, it is tricky to collect reliable information, inform patients of a diagnosis, and/or engage them in developing a management plan. This chapter discusses the connection between speaking several languages and speaker’s mind health. New research on multilingualism has impacted the author insight into the effect of learning and using two or more languages on cognition, the brain, and success and well-being across the lifetime in the last twenty years. The notion of learning various languages expose the linguistic and cognitive development in the community, the latest findings imply that people gain a swathe of health benefits, becoming more open to different languages and new learning in general. An old saying says, speaking more than one language inevitably means that one’s have access to more than one culture, the person tend to have a better understand of intercultural differences and the nuances of different subcultures within an entire culture. The finding of the study shows that knowing several languages support ones life style, boost to live longer and the speaker become a certain kind of personification of cultural dynamicity and cross-culture exchange. Consequently, multilingualism has a range of social, psychological, and lifestyle benefits. Furthermore, experts are discovering a slew of health benefits from learning multiple languages, including quicker stroke recovery and delayed dementia development.
There is a growing body of evidence based on adult neuroimaging that suggests that the brain adapts to bilingual experiences to support language proficiency. The Adolescent Brain Cognitive Development (ABCD) Study is a useful source of data for evaluating this claim during childhood, as it involves data from a large sample of American children. Using the baseline ABCD Study data collected at ages nine and ten, the goal of this study was to identify differences in cortical thickness between bilinguals and monolinguals and to evaluate how variability in English vocabulary and English use within bilinguals might explain these group differences. We identified bilingual participants as children who spoke a non-English language and were exposed to the non-English language at home. We then identified a matched sample of English monolingual participants based on age, sex, pubertal status, parent education, household income, non-verbal IQ, and handedness. Bilinguals had thinner cortex than monolinguals in widespread cortical regions. Within bilinguals, more English use was associated with greater frontal and parietal cortical thickness; greater English vocabulary was associated with greater frontal and temporal cortical thickness. These findings replicate and extend previous research with bilingual children and highlight unexplained cortical thickness differences between bilinguals and monolinguals.
Bilingualism is a natural laboratory for studying whether the brain's structural connectome is influenced by different aspects of language experience. However, evidence on how distinct components of bilingual experience may contribute to structural brain adaptations is mixed. The lack of consistency, however, may depend, at least in part, on methodological choices in data acquisition and processing. Herein, we adopted the Network Neuroscience framework to investigate how individual differences in second language (L2) exposure, proficiency , and age of acquisition (AoA)-measured as continuous between-subject variables-relate to whole-brain structural organization. We observed that L2 exposure modulated the connectivity of two networks of regions subserving language comprehension and production. L2 proficiency was associated with enhanced connectivity within a rostro-caudal network, which supports language selection and word learning. Moreover, L2 AoA and exposure affected inter-hemispheric communication between control-related regions. These findings expand mechanistic knowledge about particular environmental factors associated with specific variation in brain structure.
A large body of research has indicated that bilingualism may impact cognitive functions, as well as relevant aspects of brain function and structure, through continual practice in language control. The present review aimed to bring together relevant findings on the relationship between bilingualism and domain-general cognitive functions from a neural perspective. The final sample included 210 studies, covering findings regarding neural responses to bilingual language control and/or domain-general cognitive tasks, as well as regarding effects of bilingualism on non-task-related brain function and brain structure. The evidence indicates that a) bilingual language control likely entails neural mechanisms responsible for domain-general cognitive functions; b) bilingual experiences impact neural responses to domain-general cognitive functions; and c) bilingual experiences impact non-task-related brain function (both resting-state and metabolic function) as well as aspects of brain structure (both macrostructure and microstructure), each of which may in turn impact mental processes, including domain-general cognitive functions. Such functional and structural neuroplasticity associated with bilingualism may contribute to both cognitive and neural reserves, producing benefits across the lifespan.
The benefits of bilingualism and bilingual education
Syntactic, lexical, and phonological/phonetic knowledge are vital aspects of macro level language ability. Prior research has predominantly focused on environmental or cortical sources of individual differences in these areas; however, a growing literature suggests an auditory brainstem contribution to language performance in both typically developing (TD) populations and children with autism spectrum disorder (ASD). This study investigates whether one aspect of auditory brainstem responses (ABRs), neural response stability, which is a metric reflecting trial-by-trial consistency in the neural encoding of sound, can predict syntactic, lexical, and phonetic performance in TD and ASD school-aged children. Pooling across children with ASD and TD, results showed that higher neural stability in response to the syllable /da/ was associated with better phonetic discrimination, and with better syntactic performance on a standardized measure. Furthermore, phonetic discrimination was a successful mediator of the relationship between neural stability and syntactic performance. This study supports the growing body of literature that stable subcortical neural encoding of sound is important for successful language performance.
Significance
This article fills an important gap in the literature on structural changes in the brain that are induced by speaking two languages. It has been suggested that early lifelong bilingualism affects the structure of white matter (WM) of the brain and preserves its integrity in older age. Here we show that similar WM effects are also found in bilingual individuals who learn their second language (L2) later in life and are active users of both languages. This finding presents a strong argument for the general benefits of additional language learning and the importance of language learning and use in a naturalistic environment.
It is a timely issue to understand the impact of bilingualism upon brain structure in healthy aging and upon cognitive decline given evidence of its neuroprotective effects. Plastic changes induced by bilingualism were reported in young adults in the left inferior parietal lobule (LIPL) and its right counterpart (RIPL) (Mechelli et al., 2004). Moreover, both age of second language (L2) acquisition and L2 proficiency correlated with increased grey matter (GM) in the LIPL/RIPL. However it is unknown whether such findings replicate in older bilinguals. We examined this question in an aging bilingual population from Hong Kong. Results from our Voxel Based Morphometry study show that elderly bilinguals relative to a matched monolingual control group also have increased GM volumes in the inferior parietal lobules underlining the neuroprotective effect of bilingualism. However, unlike younger adults, age of L2 acquisition did not predict GM volumes. Instead, LIPL and RIPL appear differentially sensitive to the effects of L2 proficiency and L2 exposure with LIPL more sensitive to the former and RIPL more sensitive to the latter. Our data also intimate that such differences may be more prominent for speakers of languages that are linguistically closer such as in Cantonese-Mandarin bilinguals as compared to Cantonese-English bilinguals.
The present study explored the bilingual cognitive control mechanism by comparing Chinese-English bilinguals' language switching in a blocked picture naming paradigm against three baseline conditions, namely the control condition (a fixation cross, low-level baseline), single L1 production (Chinese naming, high-level baseline), and single L2 production (English naming, high-level baseline). Different activation patterns were observed for language switching against different baseline conditions. These results indicate that different script bilingual language control involves a fronto-parietal-subcortical network that extends to the precentral gyrus, the Supplementary Motor Area, the Supra Marginal Gyrus, and the fusiform. The different neural correlates identified across different comparisons supported that bilingual language switching involves high-level cognitive processes that are not specific to language processing. Future studies adopting a network approach are crucial in identifying the functional connectivity among regions subserving language control.
We used functional magnetic resonance imaging (fMRI) to examine the neural basis of extreme multilingual language control in a group of 50 multilingual participants. Comparing brain responses arising during simultaneous interpretation (SI) with those arising during simultaneous repetition revealed activation of regions known to be involved in speech perception and production, alongside a network incorporating the caudate nucleus that is known to be implicated in domain-general cognitive control. The similarity between the networks underlying bilingual language control and general executive control supports the notion that the frequently reported bilingual advantage on executive tasks stems from the day-to-day demands of language control in the multilingual brain. We examined neural correlates of the management of simultaneity by correlating brain activity during interpretation with the duration of simultaneous speaking and hearing. This analysis showed significant modulation of the putamen by the duration of simultaneity. Our findings suggest that, during SI, the caudate nucleus is implicated in the overarching selection and control of the lexico-semantic system, while the putamen is implicated in ongoing control of language output. These findings provide the first clear dissociation of specific dorsal striatum structures in polyglot language control, roles that are consistent with previously described involvement of these regions in nonlinguistic executive control.
Previous studies have investigated orthographic-to-phonological mapping during reading by comparing brain activation for (1) reading words to object naming, or (2) reading pseudowords (e.g., "phume") to words (e.g., "plume"). Here we combined both approaches to provide new insights into the underlying neural mechanisms. In fMRI data from 25 healthy adult readers, we first identified activation that was greater for reading words and pseudowords relative to picture and color naming. The most significant effect was observed in the left putamen, extending to both anterior and posterior borders. Second, consistent with previous studies, we show that both the anterior and posterior putamen are involved in articulating speech with greater activation during our overt speech production tasks (reading, repetition, object naming, and color naming) than silent one-back-matching on the same stimuli. Third, we compared putamen activation for words versus pseudowords during overt reading and auditory repetition. This revealed that the anterior putamen was most activated by reading pseudowords, whereas the posterior putamen was most activated by words irrespective of whether the task was reading words or auditory word repetition. The pseudoword effect in the anterior putamen is consistent with prior studies that associated this region with the initiation of novel sequences of movements. In contrast, the heightened word response in the posterior putamen is consistent with other studies that associated this region with "memory guided movement." Our results illustrate how the functional dissociation between the anterior and posterior putamen supports sublexical and lexical processing during reading.
Recent evidence suggests that lifelong bilingualism may contribute to cognitive reserve (CR) in normal aging. However, there is currently no neuroimaging evidence to suggest that lifelong bilinguals can retain normal cognitive functioning in the face of age-related neurodegeneration. Here we explored this issue by comparing white matter (WM) integrity and gray matter (GM) volumetric patterns of older adult lifelong bilinguals (N=20) and monolinguals (N =20). The groups were matched on a range of relevant cognitive test scores and on the established CR variables of education, socioeconomic status and intelligence. Participants underwent high-resolution structural imaging for assessment of GM volume and diffusion tensor imaging (DTI) for assessment of WM integrity. Results indicated significantly lower microstructural integrity in the bilingual group in several WM tracts. In particular, compared to their monolingual peers, the bilingual group showed lower fractional anisotropy and/or higher radial diffusivity in the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus bilaterally, the fornix, and multiple portions of the corpus callosum. There were no group differences in GM volume. Our results suggest that lifelong bilingualism contributes to CR against WM integrity declines in aging.
Individuals who develop bilingually typically outperform monolinguals on tests of executive functions. This advantage likely reflects enhanced prefrontal function, but the mechanisms that underlie this improvement are still poorly understood. This article describes a theory on the nature of the neural underpinnings of improved executive function in bilinguals. Specifically, we propose that growing up in a bilingual environment trains a gating system in the striatum that flexibly routes information to the prefrontal cortex. This article is divided into three sections. Firstly, literature establishing a three-way connection between bilingualism, executive function, and fronto-striatal loops is summarized. Secondly, a computational model of information processing in the basal ganglia is described, illustrating how the striatal nuclei function to transfer information between cortical regions under prerequisite conditions. Finally, this model is extended to describe how bilingualism may “train the brain,” enabling improved performance under conditions of competitive information selection during information transfer. Theoretical implications and predictions of this theory are discussed.
The experience of learning and using a second language (L2) has been shown to affect the grey matter (GM) structure of the brain. Importantly, GM density in several cortical and subcortical areas has been shown to be related to performance in L2 tasks. Here, we show that bilingualism can lead to increased GM volume in the cerebellum, a structure that has been related to the processing of grammatical rules. Additionally, the cerebellar GM volume of highly proficient L2 speakers is correlated to their performance in a task tapping on grammatical processing in an L2, demonstrating the importance of the cerebellum for the establishment and use of grammatical rules in an L2.
The article reports research investigating the way bilingualism affects cognitive and linguistic performance across the life span. In general, bilingualism appears to have both benefits and costs. Regarding costs, bilinguals typically have lower formal language proficiency than monolinguals do; for example, they have smaller vocabularies and weaker access to lexical items. The benefits, however, are that bilinguals exhibit enhanced executive control in nonverbal tasks requiring conflict resolution, such as the Stroop and Simon tasks. These patterns and their consequences are illustrated and discussed. We also propose some suggestions regarding underlying mechanisms for these effects.
We examined the effects of learning a second language (L2) on brain structure. Cortical thickness was measured in the MRI datasets of 22 monolinguals and 66 bilinguals. Some bilingual subjects had learned both languages simultaneously (0-3years) while some had learned their L2 after achieving proficiency in their first language during either early (4-7years) or late childhood (8-13years). Later acquisition of L2 was associated with significantly thicker cortex in the left inferior frontal gyrus (IFG) and thinner cortex in the right IFG. These effects were seen in the group comparisons of monolinguals, simultaneous bilinguals and early and late bilinguals. Within the bilingual group, significant correlations between age of acquisition of L2 and cortical thickness were seen in the same regions: cortical thickness correlated with age of acquisition positively in the left IFG and negatively in the right IFG. Interestingly, the monolinguals and simultaneous bilinguals did not differ in cortical thickness in any region. Our results show that learning a second language after gaining proficiency in the first language modifies brain structure in an age-dependent manner whereas simultaneous acquisition of two languages has no additional effect on brain development.
In the recent decades structural connectivity between Brocaís area and the basal ganglia has been postulated in the literature, though no direct evidence of this connectivity has yet been presented. The current study investigates this connectivity using a novel diffusion-weighted imaging (DWI) fiber tracking method in humans in vivo. Our findings suggest direct connections between sub-regions of Brocaís area and the anterior one-third of the putamen as well as the ventral anterior nucleus of the thalamus. Thus, we are the first to provide a detailed account of inferred circuitry involving basal ganglia, thalamus, and Brocaís area, which would be a prerequisite to substantiate their support of language processing.
Two studies (Golestani et al., 2007; Wong et al., 2008) have reported a positive correlation between the ability to perceive foreign speech sounds and the volume of Heschl's gyrus (HG), the structure that houses the auditory cortex. More precisely, participants with larger left Heschl's gyri learned consonantal or tonal contrasts faster than those with smaller HG. These studies leave open the question of the impact of experience on HG volumes. In the current research, we investigated the effect of early language exposure on Heschl's gyrus by comparing Spanish–Catalan bilinguals who have been exposed to two languages since childhood, to a group of Spanish monolinguals matched in education, socio-economic status, and musical experience. Manual volumetric measurements of HG revealed that bilinguals have, on average, larger Heschl's gyri than monolinguals. This was corroborated, for the left Heschl's gyrus, by a voxel-based morphometry analysis showing larger gray matter volumes in bilinguals than in monolinguals. Since the bilinguals in this study were not a self-selected group, this observation provides a clear demonstration that learning a second language is a causal factor in the increased size of the auditory cortex.
Most debate oil home ownership and risk has focused oil the management of mortgage debt. But there are other risks for home buyers in settings where housing dominates people's wealth portfolios: where the investment dimensions of property are at a premium; and where housing wealth is, de facto, all asset base for welfare. This article draws from qualitative research with 150 UK mortgage holders to assess the character, extent zinc possible mitigation of this wider risk regime. The analysis first explores the value home buyers attach to the financial returns on housing. Next we document the extent to which home equity is earmarked and used as a financial buffer. Finally, reflecting oil the merits and limitations of this tactic, we conclude by asking whether - in the interests of housing and social policy, as well as with a view to managing the economy - there is any need, scope or appetite for more actively sharing the financial risks and investment gains of housing systems anchored oil owner-occupation.
Little is known in cognitive neuroscience about the brain mechanisms and brain representations involved in bilingual language processing. On the basis of previous studies on switching and bilingualism, it has been proposed that executive functions are engaged in the control and regulation of the languages in use. Here, we review the existing evidence regarding the implication of executive functions in bilingual processing using event-related brain potentials and functional magnetic resonance imaging. Several brain potential experiments have shown an increased negativity at frontocentral areas in bilinguals, probably related to the activation of medial prefrontal regions, for different tasks, languages, and populations. Enhanced cognitive control is required in bilinguals, which also involves the recruitment of the left dorso-lateral prefrontal cortex. The degree of activation of this mechanism is also discussed considering the similarity of languages in use at the lexical, grammatical, and phonological levels. We propose that the prefrontal cortex probably mediates cognitive control in bilingual speakers through the interplay between a top-down selection-suppression mechanism and a local inhibitory mechanism in charge of changing the degree of selection-suppression of the different lexicons.
To examine neural response to spoken and printed language in children with speech sound errors (SSE).
Functional magnetic resonance imaging was used to compare processing of auditorily and visually presented words and pseudowords in 17 children with SSE, ages 8;6[years;months] through 10;10, with 17 matched controls.
When processing spoken words and pseudowords, the SSE group showed less activation than typically speaking controls in left middle temporal gyrus. They also showed greater activation than controls in several cortical and subcortical regions (e.g., left superior temporal gyrus, globus pallidus, insula, fusiform, and bilateral parietal regions). In response to printed words and pseudowords, children with SSE had greater activation than controls in regions including bilateral fusiform and anterior cingulate. Some differences were found in both speech and print processing that that may be associated with children with SSE failing to show common patterns of task-induced deactivation and/or attentional resource allocation.
Compared with controls, children with SSE appear to rely more on several dorsal speech perception regions and less on ventral speech perception regions. When processing print, numerous regions were observed to be activated more for the SSE group than for controls.
Human brain imaging has identified structural changes in gray and white matter that occur with learning. However, ascribing imaging measures to underlying cellular and molecular events is challenging. Here we review human neuroimaging findings of structural plasticity and then discuss cellular and molecular level changes that could underlie observed imaging effects. Greater dialog between researchers in these different fields would help to facilitate cross-talk between cellular and systems level explanations of how learning sculpts brain structure.
Previous research has shown that bilingual speakers have higher levels of cognitive control than comparable monolinguals, especially at older ages. The present study investigates a possible neural correlate of this behavioral effect. Given that white matter (WM) integrity decreases with age in adulthood, we tested the hypothesis that bilingualism is associated with maintenance of WM in older people. Using diffusion tensor imaging, we found higher WM integrity in older people who were lifelong bilinguals than in monolinguals. This maintained integrity was measured by fractional anisotropy (FA) and was found in the corpus callosum extending to the superior and inferior longitudinal fasciculi. We also hypothesized that stronger WM connections would be associated with more widely distributed patterns of functional connectivity in bilinguals. We tested this by assessing the resting-state functional connectivity of frontal lobe regions adjacent to WM areas with group differences in FA. Bilinguals showed stronger anterior to posterior functional connectivity compared to monolinguals. These results are the first evidence that maintained WM integrity is related to lifelong naturally occurring experience; the resulting enhanced structural and functional connectivity may provide a neural basis for "brain reserve."
Monitoring and controlling 2 language systems is fundamental to language use in bilinguals. Here, we reveal in a combined
functional (event-related functional magnetic resonance imaging) and structural neuroimaging (voxel-based morphometry) study
that dorsal anterior cingulate cortex (ACC), a structure tightly bound to domain-general executive control functions, is a
common locus for language control and resolving nonverbal conflict. We also show an experience-dependent effect in the same
region: Bilinguals use this structure more efficiently than monolinguals to monitor nonlinguistic cognitive conflicts. They
adapted better to conflicting situations showing less ACC activity while outperforming monolinguals. Importantly, for bilinguals,
brain activity in the ACC, as well as behavioral measures, also correlated positively with local gray matter volume. These
results suggest that early learning and lifelong practice of 2 languages exert a strong impact upon human neocortical development.
The bilingual brain adapts better to resolve cognitive conflicts in domain-general cognitive tasks.
In the first decade of neurocognitive word production research the predominant approach was brain mapping, i.e., investigating the regional cerebral brain activation patterns correlated with word production tasks, such as picture naming and word generation. Indefrey and Levelt (2004) conducted a comprehensive meta-analysis of word production studies that used this approach and combined the resulting spatial information on neural correlates of component processes of word production with information on the time course of word production provided by behavioral and electromagnetic studies. In recent years, neurocognitive word production research has seen a major change toward a hypothesis-testing approach. This approach is characterized by the design of experimental variables modulating single component processes of word production and testing for predicted effects on spatial or temporal neurocognitive signatures of these components. This change was accompanied by the development of a broader spectrum of measurement and analysis techniques. The article reviews the findings of recent studies using the new approach. The time course assumptions of Indefrey and Levelt (2004) have largely been confirmed requiring only minor adaptations. Adaptations of the brain structure/function relationships proposed by Indefrey and Levelt (2004) include the precise role of subregions of the left inferior frontal gyrus as well as a probable, yet to date unclear role of the inferior parietal cortex in word production.
This review considers speaking in a second language from the perspective of motor-sensory control. Previous studies relating brain function to the prior acquisition of two or more languages (neurobilingualism) have investigated the differential demands made on linguistic representations and processes, and the role of domain-general cognitive control systems when speakers switch between languages. In contrast to the detailed discussions on these higher functions, typically articulation is considered only as an underspecified stage of simple motor output. The present review considers speaking in a second language in terms of the accompanying foreign accent, which places demands on the integration of motor and sensory discharges not encountered when articulating in the most fluent language. We consider why there has been so little emphasis on this aspect of bilingualism to date, before turning to the motor and sensory complexities involved in learning to speak a second language as an adult. This must involve retuning the neural circuits involved in the motor control of articulation, to enable rapid unfamiliar sequences of movements to be performed with the goal of approximating, as closely as possible, the speech of a native speaker. Accompanying changes in motor networks is experience-dependent plasticity in auditory and somatosensory cortices to integrate auditory memories of the target sounds, copies of feedforward commands from premotor and primary motor cortex and post-articulatory auditory and somatosensory feedback. Finally, we consider the implications of taking a motor-sensory perspective on speaking a second language, both pedagogical regarding non-native learners and clinical regarding speakers with neurological conditions such as dysarthria.
Using functional magnetic resonance imaging, we found that when bilinguals named pictures or read words aloud, in their native or nonnative language, activation was higher relative to monolinguals in 5 left hemisphere regions: dorsal precentral gyrus, pars triangularis, pars opercularis, superior temporal gyrus, and planum temporale. We further demonstrate that these areas are sensitive to increasing demands on speech production in monolinguals. This suggests that the advantage of being bilingual comes at the expense of increased work in brain areas that support monolingual word processing. By comparing the effect of bilingualism across a range of tasks, we argue that activation is higher in bilinguals compared with monolinguals because word retrieval is more demanding; articulation of each word is less rehearsed; and speech output needs careful monitoring to avoid errors when competition for word selection occurs between, as well as within, language.
The neural systems underlying translation and language switching were investigated using PET. Proficient German–English adult bilinguals were scanned whilst either translating or reading visually presented words in German (L1), English (L2) or alternating L1/L2. We refer to alternating L1/L2 as `switching'. The results revealed contrasting patterns of activation for translation and switching, suggesting at least partially independent mechanisms. Translation, but not switching, increased activity in the anterior cingulate and subcortical structures whilst decreasing activation in several other temporal and parietal language areas associated with the meaning of words. Translation also increased activation in regions associated with articulation (the anterior insula, cerebellum and supplementary motor area) arguably because the reading response to the stimulus must be inhibited whilst a response in a different language is activated. In contrast, switching the input language resulted in activation of Broca's area and the supramarginal gyri, areas associated with phonological recoding. The results are discussed in terms of the cognitive control of language processes.
Objective: To investigate whether unilateral pallidotomy affects cognitive and behavioral functioning Methods: At baseline and after 6 months we assessed neuropsychological functioning in 35 patients with advanced PD. After baseline examination, patients were randomized to pallidotomy within 1 month (6 left-sided, 13 right-sided) or to pallidotomy after follow-up assessment 6 months later (n = 16; control group). We performed neuropsychological tests of language, visuospatial function, memory, attention, and executive functions. Self ratings and proxy ratings of memory problems and dysexecutive symptoms were also collected. Results: No significant differences over time were found between pallidotomy and control groups, with the exception of a decrease of verbal fluency in the left-sided pallidotomy group. Conclusions: Unilateral pallidotomy is relatively safe with respect to cognition and behavior. Left-sided pallidotomy may lead to minor deterioration in verbal fluency. The sample size of this study is too small, however, to rule out the possibility of infrequent but clinically important side effects.
The brain has an extraordinary ability to functionally and physically change or reconfigure its structure in response to environmental stimulus, cognitive demand, or behavioral experience. This property, known as neuroplasticity, has been examined extensively in many domains. But how does neuroplasticity occur in the brain as a function of an individual's experience with a second language? It is not until recently that we have gained some understanding of this question by examining the anatomical changes as well as functional neural patterns that are induced by the learning and use of multiple languages. In this article we review emerging evidence regarding how structural neuroplasticity occurs in the brain as a result of one’s bilingual experience. Our review aims at identifying the processes and mechanisms that drive experience-dependent anatomical changes, and integrating structural imaging data with current knowledge of functional neural plasticity of language and other cognitive skills. The evidence reviewed so far portrays a picture that is highly consistent with structural neuroplasticity observed for other domains: second language experience-induced brain changes, including increased gray matter density and white matter integrity, can be found in children, young adults, and the elderly; can occur rapidly with short-term language learning or training; and are sensitive to age, age of acquisition, proficiency or performance level, language-specific characteristics, and individual differences. We conclude with a theoretical perspective on neuroplasticity in language and bilingualism, and point to future directions for research.
The ability to speak two languages often marvels monolinguals, although bilinguals report no difficulties in achieving this feat. Here, we examine how learning and using two languages affect language acquisition and processing as well as various aspects of cognition. We do so by addressing three main questions. First, how do infants who are exposed to two languages acquire them without apparent difficulty? Second, how does language processing differ between monolingual and bilingual adults? Last, what are the collateral effects of bilingualism on the executive control system across the lifespan? Research in all three areas has not only provided some fascinating insights into bilingualism but also revealed new issues related to brain plasticity and language learning.
Performance of bilingual Russian–English speakers and monolingual English speakers during auditory
processing of competing lexical items was examined using eye tracking. Results revealed that both bilinguals and monolinguals experienced competition from English lexical items overlapping phonetically with an English target item (e.g., spear and speaker). However, only bilingual speakers experienced competition from Russian competitor items overlapping crosslinguistically with an English target (e.g., spear and spichki, Russian for matches). English monolinguals treated the Russian competitors as they did any other filler items. This difference in performance between bilinguals and monolinguals tested with exactly the same sets of stimuli suggests that eye movements to a crosslinguistic competitor are due to activation of the other language and to between-language competition rather than being an artifact of stimulus selection or experimental design.
Neuroimaging studies have revealed associations between intelligence and brain morphology. However, researchers have focused primarily on the anatomical features of the cerebral cortex, whereas subcortical structures, such as the basal ganglia (BG), have often been neglected despite extensive functional evidence on their relation with higher-order cognition. Here we performed shape analyses to understand how individual differences in BG local morphology account for variability in cognitive performance. Structural MRI was acquired in 104 young adults (45 men, 59 women, mean age = 19.83, SD = 1.64), and the outer surface of striatal structures (caudate, nucleus accumbens, and putamen), globus pallidus, and thalamus was estimated for each subject and hemisphere. Further, nine cognitive tests were used to measure fluid (Gf), crystallized (Gc), and spatial intelligence (Gv). Latent scores for these factors were computed by means of confirmatory factor analysis and regressed vertex-wise against subcortical shape (local displacements of vertex position), controlling for age, sex, and adjusted for brain s