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Abstract

Acquiring and speaking a second language increases demand on the processes of language control for bilingual as compared to monolingual speakers. Language control for bilingual speakers involves the ability to keep the two languages separated to avoid interference and to select one language or the other in a given conversational context. This ability is what we refer with the term “bilingual language control” (BLC). It is now well established that the architecture of this complex system of language control encompasses brain networks involving cortical and subcortical structures, each responsible for different cognitive processes such as goal maintenance, conflict monitoring, interference suppression, and selective response inhibition. Furthermore, advances have been made in determining the overlap between the BLC and the nonlinguistic executive control networks, under the hypothesis that the BLC processes are just an instantiation of a more domain‐general control system. Here, we review the current knowledge about the neural basis of these control systems. Results from brain imaging studies of healthy adults and on the performance of bilingual individuals with brain damage are discussed. Acquiring and speaking a second language (L2) increases demand on the processes of language control for bilingual as compared to monolingual speakers. Language control for bilingual speakers involves the ability to keep the two languages separated to avoid interference and to select one language or the other in a given conversational context. Here, we review the current knowledge about the neural basis of these control systems. Results from brain imaging studies of healthy adults and on the performance of bilingual individuals with brain damage are discussed.
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... They also pertain to active adult second language learners (e.g., Kuhl et al., 2016;Nichols and Joanisse, 2016;Pliatsikas et al., 2017;DeLuca et al., 2019a;Gallo et al., 2021). This is not surprising as it has been shown that adult second language acquisition, particularly in contexts of active use and engagement such as in linguistic immersion, is related to changes of brain structure and function (Abutalebi and Green, 2016;Calabria et al., 2018;Fedeli et al., 2021) where language processing and control cross-over with executive functioning (see Pliatsikas, 2019 for review). ...
... Beyond behavioral cognitive function measures, there is greater consistency of findings across bilingual neuroimaging studies at all ages. As we review in detail below, a plurality of relevant studies shows changes in the bilingual brain that overlap topographically with regions highly implicated in language processing/control, memory, and executive functioning (e.g., De Baene et al., 2015;Abutalebi and Green, 2016;Calabria et al., 2018). fMRI studies show increased efficiency in neural recruitment during task performance in bilinguals, even when there are no measurable behavioral differences (e.g., Abutalebi et al., 2012;DeLuca et al., 2020). ...
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As a result of advances in healthcare, the worldwide average life expectancy is steadily increasing. However, this positive trend has societal and individual costs, not least because greater life expectancy is linked to higher incidence of age-related diseases, such as dementia. Over the past few decades, research has isolated various protective “healthy lifestyle” factors argued to contribute positively to cognitive aging, e.g., healthy diet, physical exercise and occupational attainment. The present article critically reviews neuroscientific evidence for another such factor, i.e., speaking multiple languages. Moreover, with multiple societal stakeholders in mind, we contextualize and stress the importance of the research program that seeks to uncover and understand potential connections between bilingual language experience and cognitive aging trajectories, inclusive of the socio-economic impact it can have. If on the right track, this is an important line of research because bilingualism has the potential to cross-over socio-economic divides to a degree other healthy lifestyle factors currently do not and likely cannot.
... To shed light on the brain activity that is associated with BLC, researchers have conducted fMRI and PET studies on bilingual language switching tasks (e.g., de Bruin et al., 2014;Guo et al., 2011;Liu et al., 2021a, b, c; for a review, see Calabria et al., 2018). Abutalebi and Green (2008) proposed a neurocognitive model of bilingual language switching, which consisted of five brain regions for bilingual language switching: the left dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), caudate nucleus, and bilateral supramarginal gyri (SMG). ...
... The pre-SMA/dACC complex was also consistently activated in both switching domains. The pre-SMA/dACC complex has been attributed to conflict monitoring and resolution in both linguistic and non-linguistic tasks (Botvinick et al., 2001;Calabria et al., 2018). The activity of the pre-SMA/dACC complex has been consistently reported when performing cognitive control tasks such as Stroop, flanker, or task switching experiments (Botvinick et al., 2004;Carter et al., 1999;Hyafil et al., 2009), as well as during language switching tasks (Branzi et al., 2016b;Liu et al., 2021a, b ;Guo et al., 2011;Yuan et al., 2021). ...
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The extent to which bilingual language control (BLC) is related to domain-general executive control (EC) remains unclear. The present study applied activation likelihood estimation (ALE) meta-analyses to identify commonalities and distinctions in the brain regions across domains reported in neuroimaging studies. We specifically compare results from two experimental tasks: language switching, a typical measure of BLC, and task switching, an experiment that measures EC. Conjunction analyses showed a domain-general pattern between language switching and task switching, with convergent activity in the left dorsolateral prefrontal cortex (DLPFC), pre-SMA/dACC complex (pre-supplementary motor area/dorsal anterior cingulate cortex), and left precuneus. Regarding domain-specificity, contrast analyses revealed stronger convergence of activation in the left fusiform gyrus and occipital gyrus in language switching compared to task switching, and conversely, stronger convergence of activation in the left DLPFC in task switching. Overall, these findings illustrate the partially overlapping nature of the neural circuits involved in BLC and EC.
... Such a model can easily be extended to comprehension in which lexical/structural items are activated differently depending on the language and wider situation (see also Blanco-Elorrieta & Caramazza, 2021). The recurrence of specific interactional contexts could lead to neural adaptations to their specific control demands (Calabria et al., 2018). The alpha band power increase we have seen in the context with a bilingual partner, who used code-switching prior to the experiment and activated the code-switching context, could have been partly related to sustained open language control. ...
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Beta band power Alpha band power Gamma band power A B S T R A C T Code-switching, i.e. the alternation between languages in a conversation, is a typical, yet socially-constrained practice in bilingual communities. For instance, code-switching is permissible only when other conversation partners are fluent in both languages. Studying code-switching provides insight in the cognitive and neural mechanisms underlying language control, and their modulation by linguistic and non-linguistic factors. Using time-frequency representations, we analyzed brain oscillation changes in EEG data recorded in a prior study (Kaan et al., 2020). In this study, Spanish-English bilinguals read sentences with and without switches in the presence of a bilingual or monolingual partner. Consistent with prior studies, code-switches were associated with a power decrease in the lower beta band (15-18 Hz). In addition, code-switches were associated with a power decrease in the upper gamma band (40-50 Hz), but only when a bilingual partner was present, suggesting the semantic/pragmatic processing of code-switches differs depending on who is present.
... Taken together, this review provides a necessary update on the discussion surrounding bilingual inhibitory control. Moreover, this review goes beyond previous reviews of language control (e.g., Abutalebi & Green, 2007;Bobb & Wodniecka, 2013;Calabria et al., 2018;Declerck & Philipp, 2015a;Kroll et al., 2008) by organizing this review systematically according to four major empirical effects supposed to index bilingual inhibition (asymmetrical switch costs, n-2 language repetition costs, reversed language dominance, blocked language order effect; see below), covering both language production and language comprehension, and separating the assessment of the empirical replicability of the effects themselves from the assessment of the evidence in support of their underlying theoretical assumptions. In doing so, we raise and discuss open questions that still need to be addressed in the context of bilingual inhibition. ...
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To achieve fluent language processing as a bilingual, a dominant theoretical framework assumes that the nontarget language is inhibited. This assumption is based on several empirical effects that are typically explained with inhibitory control. In the current article, we discuss four prominent effects linked to bilingual inhibition in language production (i.e., asymmetrical switch costs, n-2 language repetition costs, reversed language dominance, and the blocked language order effect). We argue that these effects require more empirical examination in order to arrive at a firmer basis for the assumption that inhibition plays a major role during bilingual language control. In particular, the empirical replicability of the phenomena themselves needs to be established more firmly, the underlying theoretical assumptions need further examination, and the alternative explanations of the empirical effects need to be scrutinized. In turn, we conclude that inhibitory control may provide a coherent framework for bilingual language production while outlining the challenges that the inhibition account still needs to face. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
... While these studies suggest domain-general cognitive involvement in language control, not all studies and tasks investigating the relationship between domain-specific and domain-general control have consistently found this involvement (for a review, see Calabria et al., 2018). The following section will explore the proposition by Anthony and Blumenfeld (2019) that these contradictory results may stem from unclear distinctions between bilinguals in terms of bilingual profiles. ...
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The ability of bilingual individuals to manage two competing languages is assumed to rely on both domain-specific language control and domain-general control mechanisms. However, previous studies have reported mixed findings about the extent and nature of cross-domain generality. The present study examined the role of language dominance, along with bilingual language experience, in the relationship between word recognition and domain-general cognitive control. Two single-language lexical decision tasks (one in L1 and another in L2) and a domain-general flanker task were administered to bilinguals who live in the sociolinguistic context of a minority and a majority language, namely, Uyghur (L1) and Chinese (L2), respectively. The results showed a diversity in language dominance patterns with better performance in L2 than L1 in the recognition modality, even for participants who self-identified as globally being dominant in L1. This finding reflected all bilinguals’ self-evaluation that their preferred language for reading was L2, suggesting that language dominance is dynamic, depending on what language modality is measured. Furthermore, it was found that an earlier onset age of L2 acquisition (but not recent exposure) and a higher across-modality dominance in L2 were related to faster L2 word recognition. When self-reported language dominance was operationalised as a grouping variable, it was further found that both across-modality L1- and L2-dominant bilingual participants demonstrated a significant relationship between L2 word recognition and domain-general monitoring control, while only L1-dominant bilinguals additionally tapped into inhibitory control, indexed by the flanker effect during L2 word recognition. These findings suggest that language dominance has an impact on the extent and nature of the overlap in control mechanisms across specific linguistic and domain-general cognitive domains and add evidence to a domain-general monitoring account of bilingual word recognition.
... Bilingual speakers commonly select the appropriate language to use in different contexts, such as using English at work and Chinese at home, or switching between two languages in the same conversation. For a successful code-switching production, bilinguals need to access the appropriate language and resolve the competition from the unwanted (Bonfieni, Branigan, Pickering & Sorace, 2019;Green, 1998;Green & Abutalebi, 2013), a process that requires additional demand on general-domain cognitive control mechanisms (e.g., Abutalebi & Green, 2007, 2008Calabria, Costa, Green & Abutalebi, 2018). ...
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This study explored how bilingual code-switching habits affect cognitive shifting and inhibition. Habitual code-switching from 31 Mandarin-English bilingual adults were collected through the Language and Social Background Questionnaire (Anderson et al., 2018) and the Bilingual Switching Questionnaire (Rodriguez-Fornells et al., 2012). All participants performed verbal and nonverbal switching tasks, including the verbal fluency task, a bilingual picture-naming and colour-shape switching task. A Go/No-go task was administered to measure the inhibitory control of participants. Frequent bilingual switchers showed less efforts and time costs in switching into naming pictures in Chinese as well as switching across different nonverbal tasks in the colour-shape switching task. Additionally, bilinguals intensively engaged in dense code-switching practices showed advantages in conflicts monitoring and inhibition in the Go/No-go task. The cooperative control of two language in participants’ dense code-switching practices was observed. Overall, the study, observing not only the connections between intensity of single-language context experience and goal maintenance efficiency, partially supported the Adaptive Control Hypothesis (ACH)’ prediction (Green & Abutalebi, 2013). However, it also indicated the facilitations of dense code-switching experience on response inhibition proficiency, which was inconsistent with ACH’s prediction. The practical implications of how different bilingual language experiences affect human cognition are discussed.
... Previous research has shown bilingualism contributes to the building-up of brain reserves in older age (Calabria et al., 2018). Studies employing diffusion tensor imaging (DTI) have found that older bilinguals maintain higher integrity in several WM tracts supporting language processing and control, specifically the corpus callosum (CC), superior longitudinal fasciculi (SLF) bilaterally, and right inferior fronto-occipital fasciculus (IFOF) (Anderson et al., 2018a;Luk et al., 2011). ...
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Bilingualism has been associated with increases in compensatory mechanisms to age-related neurocognitive decline thus delaying dementia symptom onset and leading to a more favorable trajectory of neurocognitive aging. However, most research to date has examined bilingualism-induced effects on neurocognition within older age ranges or young adults– with middle-aged individuals typically not being a population of interest. Furthermore, bilingualism is often treated as a dichotomous variable, despite it being a heterogeneous experience on an individual level. In the present study we employed diffusion tensor imaging (DTI) to examine whether bilingualism, and the degree of engagement in bilingual experience, modulates the nature or rate of white matter decline associated with aging. DTI data and language history data were collected from a cohort of monolingual and bilingual individuals spanning a wide age range. Two separate analyses were run. First, generalized additive models were run on matched monolingual and bilingual samples, examining effects of age on the trajectory of white matter integrity and how bilingualism modulates this effect. This analysis revealed a significant effect of age within the monolingual group for fractional anisotropy values in the right superior longitudinal fasciculus. However, the age effect within the bilingual group was not significant, indicating a faster decline in white matter integrity within the monolingual cohort. Second, general linear models were run on the entire participant sample, examining an interaction between age and degree of bilingual engagement on white matter integrity. Results from this analysis indicate that increased engagement in bilingual language use across the lifespan correlates with a slower decline in white matter integrity with age. Together these results indicate bilingualism, and specifically degree of bilingual engagement, impacts the trajectory of age-related decline in white matter integrity across the lifespan.
Thesis
La compréhension du langage, bien qu’étant omniprésente au quotidien, est un processus cognitif complexe dont les mécanismes et les réseaux corticaux sous-jacents sont encore peu compris. Lors de la compréhension, différents processus cognitifs semblent entrer en jeu. Il est notamment proposé que les performances de compréhension soient modulées non seulement par le type d’information linguistique traitée mais également par des mécanismes domaine-généraux. L'objectif de cette thèse était d’une part d'évaluer les interactions entre la compréhension du langage oral et le contrôle cognitif, et d’autre part de caractériser le traitement des informations sémantiques et syntaxiques dans la compréhension et dans les interactions précédemment décrites. Nous avons pour cela mené plusieurs études avec des mesures comportementales (Etude 1-4) et en électroencéphalographie intracrânienne -SEEG- (Etude 5-7). Dans ces études, nous avons mis au point différents paradigmes expérimentaux permettant d’évaluer la relation entre les processus de compréhension du langage et ceux de contrôle cognitif de manière causale et corrélationnelle. Nous avons proposé des manipulations linguistiques en lien avec les informations lexico-sémantiques et syntaxiques. Nos études montrent que dans des situations d’ambiguïté linguistique les processus de contrôle cognitif sont impliqués et permettent de meilleures performances. De plus, d’après nos résultats les liens entre la compréhension du langage oral et le contrôle cognitif semblent être bidirectionnelle. Nos études en sEEG se sont centrées tout d’abord sur la caractérisation du rôle fonctionnel des différentes bandes de fréquence (alpha, beta, low-gamma et high-gamma) lors du traitement de l’information sémantique et syntaxique. Ces études montrent que le réseau canonique du langage présente un pattern d’activité majoritairement marqué par une absence de spécificité fonctionnelle à travers les quatre bandes de fréquences explorées. Au niveau temporal deux sous-réseaux semblent émerger en termes de patterns d’activité spectrale avec un traitement sémantique soutenu par l’activité de hautes fréquences tandis que le traitement syntaxique semble être soutenu par un traitement de basses fréquences. De plus, les résultats montrent qu’une même région peut présenter une dissociation fonctionnelle en lien avec la fréquence évaluée. Finalement, nous avons évalué l’effet de ce type de dissociation fonctionnelle en lien avec les processus de contrôle cognitif (control attentionnel). Cette dernière étude, en cours, semble montrer des modulations attentionnelles au sein des voies ventrale et dorsale en fonction de la spécialisation linguistique du réseau évalué. L’ensemble de ces travaux de thèse apportent des arguments quant à l’existence de liens entre les processus de compréhension du langage oral et ceux de contrôle cognitif. Ces résultats ouvrent des perspectives au niveau appliqué et notamment dans la proposition de méthodes interventionnelles par l’entraiment du contrôle cognitif lors de troubles de la compréhension.
Article
Previous research has shown that language switching is costly, and that these costs are likely to persist even when speakers are given ample time to prepare. The aim of this study was to determine whether there are cognitive limitations to speakers' ability to prepare for a switch, or whether a new language can be prepared in advance and any cost to switch language eliminated. To explore this, language switching costs were measured in a group of Dutch-English (L1-L2) bilinguals who named pictures in their two languages while the preparation time was manipulated. The participants were given either no time to prepare (cue to stimulus interval, CSI: 0 ms), or some time to prepare, for the target language (CSI: 250, 500, and 800 ms). The results revealed that when speakers had no time to prepare, language switching was costly. However, when preparation time was provided, switching costs disappeared. This suggests that there might be no cognitive limitations to the ability to prepare for a language switch, and that, provided enough preparation time, the effort to switch language could be eliminated. This finding might also explain why normal code-switched conversations seem effortless, as speakers typically have ample time to prepare for the language switch.
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The present functional magnetic resonance imaging (fMRI) study investigated influences of language contexts on inhibitory control and the underlying neural processes. Thirty Cantonese–Mandarin–English trilingual speakers, who were highly proficient in Cantonese (L1) and Mandarin (L2), and moderately proficient in English (L3), performed a picture-naming task in three dual-language contexts (L1-L2, L2-L3, and L1-L3). After each of the three naming tasks, participants performed a flanker task, measuring contextual effects on the inhibitory control system. Behavioral results showed a typical flanker effect in the L2-L3 and L1-L3 condition, but not in the L1-L2 condition, which indicates contextual facilitation on inhibitory control performance by the L1-L2 context. Whole brain analysis of the fMRI data acquired during the flanker tasks showed more neural activations in the right prefrontal cortex and subcortical areas in the L2-L3 and L1-L3 condition on one hand as compared to the L1-L2 condition on the other hand, suggesting greater involvement of the cognitive control areas when participants were performing the flanker task in L2-L3 and L1-L3 contexts. Effective connectivity analyses displayed a cortical-subcortical-cerebellar circuitry for inhibitory control in the trilinguals. However, contrary to the right-lateralized network in the L1-L2 condition, functional networks for inhibitory control in the L2-L3 and L1-L3 condition are less integrated and more left-lateralized. These findings provide a novel perspective for investigating the interaction between bilingualism (multilingualism) and inhibitory control by demonstrating instant behavioral effects and neural plasticity as a function of changes in global language contexts.
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In a recent review, Mukadam, Sommerlad, and Livingston (2017) argue that bilingualism offers no protection against cognitive decline. The authors examined the results of 13 studies (five prospective, eight retrospective) in which monolinguals and bilinguals were compared for cognitive decline and onset of dementia symptoms. Analysis of four of the five prospective studies resulted in the conclusion that there was no difference between monolinguals and bilinguals, whereas seven of the eight retrospective studies actually showed bilingualism to result in a four-to-five year delay of symptom onset. The authors decided to ignore the results from the retrospective studies in favor of those from the prospective studies, reasoning that the former may be confounded by participants' cultural background and education levels. In this commentary, we argue that most of these studies actually controlled for these two variables and still found a positive effect of bilingualism. Furthermore, we argue that the meta-analysis of the prospective studies is not complete, lacking the results of two crucial reports. We conclude that the literature offers substantial evidence for a bilingual effect on the development of cognitive decline and dementia.
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A neglected question regarding cognitive control is how control processes might detect situations calling for their involvement. The authors propose here that the demand for control may be evaluated in part by monitoring for conflicts in information processing. This hypothesis is supported by data concerning the anterior cingulate cortex, a brain area involved in cognitive control, which also appears to respond to the occurrence of conflict. The present article reports two computational modeling studies, serving to articulate the conflict monitoring hypothesis and examine its implications. The first study tests the sufficiency of the hypothesis to account for brain activation data, applying a measure of conflict to existing models of tasks shown to engage the anterior cingulate. The second study implements a feedback loop connecting conflict monitoring to cognitive control, using this to simulate a number of important behavioral phenomena.
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Research on the neural bases of bilingual language control has largely overlooked the role of preparatory processes, which are central to cognitive control. Additionally, little is known about how the process involved in global language selection may differ from those involved in the selection of words and morpho-syntactic rules for manipulating them. These processes were examined separately in an fMRI experiment, with an emphasis on understanding how and when general cognitive control regions become activated. Results of region-of-interest analyses on 23 early Spanish-English bilinguals showed that the anterior cingulate cortex (ACC) was primarily engaged during the language preparation phase of the task, whereas the left prefrontal (DLPFC) and pre-supplementary motor areas showed increasing activation from preparation to execution. Activation in the basal ganglia (BG), left middle temporal lobe, and right precentral cortical regions did not significantly differ throughout the task. These results suggest that three core cognitive control regions, the ACC, DLPFC, and BG, which have been previously implicated in bilingual language control, engage in distinct neurocognitive processes. Specifically, the results are consistent with the view that the BG "keep track" of the target language in use throughout various levels of language selection, that the ACC is particularly important for top-down target language preparation, and that the left prefrontal cortex is increasingly involved in selection processes from preparation through task execution.
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Speaking more than one language is associated with neurocognitive benefits in seniors (Alladi et al. 2013). Few studies however have tested this hypothesis directly by comparing bilingual seniors who vary in chronological age. We report a Voxel-Based Morphometry (VBM) study showing cumulative effects of age on grey matter volume (GMV) in brain structures that are involved in cognitive control in bilingual seniors and found no differences in RT or accuracy between bilingual and monolingual seniors on a behavioral test of cognitive control called the Attentional Network Task (ANT), and no differences in GMV for selected ROIs between groups. However, chronological age predicted the size of interference and conflict effects for monolingual speakers only. We also observed a more widespread pattern of bilateral aging-effcts in brain regions that are classically associated with aging in monolingual speakers compared to bilingual speakers. Notably, GMV in the dorsal anterior cingulate cortex (dACC) and the level of daily exposure to a second language (L2) independently predict performance on the ANT in bilingual speakers. We conclude that regular (daily) bilingual experience mitigates the typical effects of aging on cognitive control at the behavioral and the neural level.
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Neural basis of language switching and the cognitive models of bilingualism remain controversial. We explored the functional neuroanatomy of language switching implementing a new multimodal protocol assessing neuropsychological, functional magnetic resonance and intraoperative electrical stimulation mapping results. A prospective series of 9 Spanish–Catalan bilingual candidates for awake brain surgery underwent a specific language switching paradigm implemented both before and after surgery, throughout the electrical stimulation procedure and during functional magnetic resonance both pre- and postoperatively. All patients were harboring left-hemispheric intrinsic brain lesions and were presenting functional language-related activations within the affected hemisphere. Language functional maps were reconstructed on the basis of the intraoperative electrical stimulation results and compared to the functional magnetic resonance findings. Single language-naming sites (Spanish and Catalan), as well as language switching naming sites were detected by electrical stimulation mapping in 8 patients (in one patient only Spanish related sites were detected). Single naming points outnumbered the switching points and did not overlap with each other. Within the frontal lobe, the single language naming sites were found significantly more frequently within the inferior frontal gyrus as compared to the middle frontal gyrus [X² (1) = 20.3, p < .001]. Contrarily, switching naming sites were distributed across the middle frontal gyrus significantly more often than within the inferior frontal gyrus [X² (1) = 4.1, p = .043]. Notably, there was not always an overlap between functional magnetic resonance and electrical stimulation mapping findings. After surgery, patients did not report involuntary language switching and their neuropsychological scores did not differ significantly from the pre-surgical examinations. Our results suggest a functional division of the frontal cortex between naming and language switching functions, supporting that non-language specific cognitive control prefrontal regions (middle frontal gyrus) are essential to maintain an effective communication together with the classical language-related sites (inferior frontal gyrus).
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The present study investigated the neural correlates of naming disadvantage of the dominant language under the mixed language context. Twenty one unbalanced Chinese-English bilinguals completed a cued picture naming task while being scanned with functional magnetic resonance imaging (fMRI). Behavioral results showed that naming pictures in the second lanuage (L2) was significantly slower than naming pictures in the first language (L1) under a single language context. When comparing picture naming in L2 to naming in L1, enhanced activity in the left inferior parietal lobule and left cerebellum was observed. On the contrary, naming pictures in Chinese (L1) was significantly slower than naming in English (L2) under the mixed language context. The fMRI results showed that bilateral inferior frontal gyri, right middle frontal gyrus, and right supplementary motor area were activated to a greater extent in L1 than in L2. These results suggest that the dominant language is inhibited to a greater extent to ensure the production of the second language under the mixed language context. Therefore, more attentional control resources are recruited when bilinguals produced the dominant language. The present study, for the first time, reveals neural correlates of L1 naming disadvantage under the mixed language context.