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Abstract
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.
FULL TEXT: https://www.sciencedirect.com/science/article/abs/pii/S0028393222001324?via%3Dihub
... Notably, the recruitment of areas such as the ACC and PFC is not exclusive to language control; as they also play a role in cognitive control (Aarts et al., 2008;Cools, 2011;Frank, 2011;Kerns et al., 2004). Evidence from multiple studies supports that language control and cognitive control share overlapping neural mechanisms across widely distributed brain regions (e.g., Anderson et al., 2018;De Baene et al., 2015;Weissberger et al., 2015;Wu et al., 2019;Jiao et al., 2022). For instance, Jiao et al. (2022) conducted a meta-analysis of neuroimaging studies, identifying a prominent shared activation pattern in the left dorsolateral PFC, presupplementary motor area (SMA)/dorsal ACC, and left precuneus during both language switching tasks and non-verbal switching tasks. ...
... Evidence from multiple studies supports that language control and cognitive control share overlapping neural mechanisms across widely distributed brain regions (e.g., Anderson et al., 2018;De Baene et al., 2015;Weissberger et al., 2015;Wu et al., 2019;Jiao et al., 2022). For instance, Jiao et al. (2022) conducted a meta-analysis of neuroimaging studies, identifying a prominent shared activation pattern in the left dorsolateral PFC, presupplementary motor area (SMA)/dorsal ACC, and left precuneus during both language switching tasks and non-verbal switching tasks. However, some studies challenge this view, suggesting that the mechanisms involved in both types of switching tasks may be primarily distinct (Blanco-Elorrieta & Pylkkä nen, 2016;Magezi et al., 2012). ...
... As neuroimaging techniques are inherently correlational rather than indicative of causality (e.g., Pestalozzi et al., 2020;Wu et al., 2024aWu et al., , 2025, brain activity triggered by stimuli does not guarantee that all activated regions are responsible for the task; as a result, some studies may report epiphenomenally activated regions that are absent in others. For instance, the LIFG has been shown to activate during both language switching and non-verbal switching tasks in fMRI studies (e.g., De Baene et al., 2015;Jiao et al., 2022), while the LPTL is essential for language processing (e.g., Binder et al., 1996;Choi et al., 2015;Friederici & Kotz, 2003;Meyer et al., 2005;Powell et al., 2007). However, the causal mechanisms underlying their involvement in these processes remain inadequately explored. ...
Previous research has mainly explored the relationship between bilingual language control and domain-general cognitive control through behavioral correlations, often revealing epiphenomenal links rather than causality. This study utilizes transcranial magnetic stimulation (TMS) to investigate the causal roles of the left inferior frontal gyrus (LIFG) and left posterior temporal lobe (LPTL) in these processes among 33 unbalanced Chinese-English bilinguals. Continuous theta burst stimulation was applied in separate sessions, with vertex stimulation as a control. Our results demonstrate that LIFG stimulation significantly increased switching costs in non-verbal switching tasks, highlighting its role in domain-general cognitive control. Conversely, LPTL stimulation did not affect switching or mixing costs in language or non-verbal switching tasks, suggesting no causal involvement. However, it reduced reaction times during language switching tasks, underscoring its specialization in language processing. These findings highlight potential distinctions between the neural mechanisms of bilingual language control and domain-general cognitive control, particularly in the LIFG.
... Bilinguals are constantly faced with the challenge of controlling their two languages to avoid interference from the language not in use. There is an ongoing debate on whether and how the language control mechanisms recruit domain-general cognitive control processes (Green, 1998;Jiao et al., 2022a). Though it has been repeatedly observed that language control during production engages domain-general inhibition (Green, 1998;Jiao et al., 2022a;Kang et al., 2020;Linck et al., 2012;Liu et al., 2014; but see Calabria et al., 2012Calabria et al., , 2015Prior & Gollan, 2013;Segal et al., 2019), the association between domain-general cognitive control and language control during comprehension is relatively under-researched, and the relevant studies have yielded inconsistent findings. ...
... There is an ongoing debate on whether and how the language control mechanisms recruit domain-general cognitive control processes (Green, 1998;Jiao et al., 2022a). Though it has been repeatedly observed that language control during production engages domain-general inhibition (Green, 1998;Jiao et al., 2022a;Kang et al., 2020;Linck et al., 2012;Liu et al., 2014; but see Calabria et al., 2012Calabria et al., , 2015Prior & Gollan, 2013;Segal et al., 2019), the association between domain-general cognitive control and language control during comprehension is relatively under-researched, and the relevant studies have yielded inconsistent findings. ...
This study investigated the engagement of domain-general cognitive control during the comprehension of dense code-switching sentences. Stimulus-locked event-related potentials (ERPs) were measured while L1-dominant Chinese–English bilinguals read switch and non-switch sentences. The results of the reading task revealed language dominance effects on the N400, left anterior negativity (LAN) and late positive component (LPC). The language dominance effects at lexical level (i.e., on the N400 and LAN) were modulated by individual differences in monitoring capacity. In contrast, inhibition capacity predicted code-switching costs at the sentence level (i.e., for the LPC component). The results suggest that proactive monitoring and reactive inhibition affect different processing stages during the comprehension of dense code-switching sentences. These findings partially align with processing models of code-switching incorporating a dual control mode perspective and contribute new insight into the dynamic interplay between reactive and proactive control processes.
... Cognitive Neuroscience (CN) is an interdisciplinary subject that seeks practical and theoretical methodologies that establish connections between brain functions and mental processes (Banich and Compton, 2018). Moreover, CN research has brought relevant biological and psychological discoveries about cognitive processes such as memory (Jimenez et al., 2020;Vaz et al., 2020;Bergmann and Ortiz-Tudela, 2023), attention (Li et al., 2020;Jacob et al., 2021;Niu et al., 2021), language (García et al., 2020;Finlayson et al., 2021;Jiao et al., 2022) and emotions (Alexander et al., 2021;Eslinger et al., 2021;Quadt et al., 2022). Cognitive processes are also involved in the learning process, and recent research is creating learning models to understand the different scenarios where this process occurs (Parong and Mayer, 2021;Zhang et al., 2021;Skulmowski and Xu, 2022). ...
Introduction
In transitioning from Industry 4.0 to the forthcoming Industry 5.0, this research explores the fusion of the humanistic view and technological developments to redefine Continuing Engineering Education (CEE). Industry 5.0 introduces concepts like biomanufacturing and human-centricity, embodying the integration of sustainability and resiliency principles in CEE, thereby shaping the upskilling and reskilling initiatives for the future workforce. The interaction of sophisticated concepts such as Human-Machine Interface and Brain-Computer Interface (BCI) forms a conceptual bridge toward the approaching Fifth Industrial Revolution, allowing one to understand human beings and the impact of their biological development across diverse and changing workplace settings.
Methods
Our research is based on recent studies into Knowledge, Skills, and Abilities taxonomies, linking these elements with dynamic labor market profiles. This work intends to integrate a biometric perspective to conceptualize and describe how cognitive abilities could be represented by linking a Neuropsychological test and a biometric assessment. We administered the brief Neuropsychological Battery in Spanish (Neuropsi Breve). At the same time, 15 engineering students used the Emotiv insight device that allowed the EEG recollection to measure performance metrics such as attention, stress, engagement, and excitement.
Results
The findings of this research illustrate a methodology that allowed the first approach to the cognitive abilities of engineering students to be from neurobiological and behavioral perspectives. Additionally, two profiles were extracted from the results. The first illustrates the Neuropsi test areas, its most common mistakes, and its performance ratings regarding the students' sample. The second profile shows the interaction between the EEG and Neuropsi test, showing engineering students' cognitive and emotional states based on biometric levels.
Discussions
The study demonstrates the potential of integrating neurobiological assessment into engineering education, highlighting a significant advancement in addressing the skills requirements of Industry 5.0. The results suggest that obtaining a comprehensive understanding of students' cognitive abilities is possible, and educational interventions can be adapted by combining neuropsychological approaches with EEG data collection. In the future, it is essential to refine these evaluation methods further and explore their applicability in different engineering disciplines. Additionally, it is necessary to investigate the long-term impact of these methods on workforce preparation and performance.
... Some studies found supporting evidence for this explanation. For instance, Jiao et al. (2022) conducted a meta-analysis of neuroimaging studies to investigate the neural mechanisms underlying bilingual language control and EF. Using contrast analyses, they found that 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 dorsolateral prefrontal cortex in task switching. ...
In processing their two languages, bilinguals have to selectively attend to the target language and reduce interference from the non-target language. This experience may have specific cognitive consequences on Executive Functions (EF) through bilingual language processing. Some studies found cognitive consequences in executive functioning skills. However, other studies did not replicate these findings or found a bilingual disadvantage. The aim of this study was to test for the cognitive consequences of bilingualism in EF among a large number of young adults using a latent variable approach, to rule out non-EF task differences as an explanation for inconsistency across studies. Also, we were interested in testing the EF structure using the Confirmatory Factor Analysis (CFA) approach. The results did not support a cognitive consequence of bilingualism and also the EF structure was the same for both groups. We discuss other possible variables that might contribute to the mixed results across studies.
... Functional MRI studies of the DLPFC contributions to language function have largely investigated its shared role in executive functioning/working memory and language control processes, especially for bilingual and multilingual individuals. Meta-analytic evidence suggests that the DLPFC cooperates with a network of other regions including the pre-supplementary motor area, the anterior cingulate cortex, and the precuneus during language switching for bilingual individuals [82]. DLPFC activation has also been observed processing complex syntax [83] and in reading comprehension [84], especially when work-ing memory demands were higher in the task employed. ...
Functional MRI is a well-established tool used for pre-surgical planning to help the neurosurgeon have a roadmap of critical functional areas that should be avoided, if possible, during surgery to minimize morbidity for patients with brain tumors (though this also has applications for surgical resection of epileptogenic tissue and vascular lesions). This article reviews the locations of secondary language centers within the brain along with imaging findings to help improve our confidence in our knowledge on language lateralization. Brief overviews of these language centers and their contributions to the language networks will be discussed. These language centers include primary language centers of “Broca’s Area” and “Wernicke’s Area”. However, there are multiple secondary language centers such as the dorsal lateral prefrontal cortex (DLPFC), frontal eye fields, pre- supplemental motor area (pre-SMA), Basal Temporal Language Area (BTLA), along with other areas of activation. Knowing these foci helps to increase self-assurance when discussing the nature of laterality with the neurosurgeon. By knowing secondary language centers for language lateralization, via fMRI, one can feel confident on providing neurosurgeon colleagues with appropriate information on the laterality of language in preparation for surgery.
... Previous studies using the code-switch paradigm have highlighted several brain regions and connectivity patterns associated with language control (De Baene et al. 2015;De Bruin et al. 2014;Reverberi et al. 2015;Wang et al. 2007). Interestingly, neuroimaging evidence has implicated overlapping brain regions between executive functions (e.g., non-linguistic language control) and language control in processing emotional stimuli and regulating emotional status (De Baene et al. 2015;De Bruin et al. 2014;Hosoda et al. 2012;Jiao et al. 2022b;Weissberger et al. 2015). The anterior cingulate cortex (ACC) is an important brain region in the neural network associated with executive functions and language control. ...
Research has shown that several variables affect language control among bilingual speakers but the effect of affective processing remains unexplored. Chinese–English bilinguals participated in a novel prime-target language switching experiment in which they first judged the affective valence (i.e., positive or negative) of auditorily presented words and then named pictures with neutral emotional valence in either the same (non-switch trial) or different language (switch trial). Brain activity was monitored using functional magnetic resonance imaging (fMRI). The behavioral performance showed that the typical switch cost (i.e., the calculated difference between switch and non-switch trials) emerged after processing positive words but not after negative words. Brain imaging demonstrated that processing negative words immediately before non-switch picturing naming trials (but not for switch trials) increased activation in brain areas associated with domain-general cognitive control. The opposite patterns were found after processing positive words. These findings suggest that an (emotional) negative priming effect is induced by spontaneous exposure to negative words and that these priming effects may be triggered by reactive emotional processing and that they may interact with higher level cognitive functions.
... It is still an ongoing debate to what extent there is a relation between language control and executive control in bilinguals (for reviews, see Bialystok, 2017;Lehtonen et al., 2018;Wodniecka et al., 2020). It has been widely accepted that both languages are activated in parallel during bilingual language production (Jiao, Meng, Wang, Schwieter, & Liu, 2022;Kroll, Bobb, & Wodniecka, 2006;Kroll, Dussias, Bice, & Perrotti, 2015) and bilingual language comprehension (Marian & Spivey, 2003;Thierry & Wu, 2007). This suggests the engagement of control mechanisms during bilingual language processing. ...
The relationship between bilingual language control and executive control is debated. The present study investigated the effect of short‐term language switching in a comprehension task on executive control performance in unbalanced bilinguals. Participants were required to perform a context task and an executive control task (i.e., flanker task) in sequence. A picture‐word matching task created different language contexts in Experiment 1 (i.e., L1, L2, and dual‐language contexts). By modifying the color‐shape switching task, we created different contexts that do not involve language processing in Experiment 2 (i.e., color, shape, and dual context). Experiment 1 showed overall faster responses (in both congruent and incongruent trials) in the flanker task after a language switching context than after single (L1 or L2) contexts. This suggests that the language switching in a comprehension task affected general monitoring performance. By contrast, the nonlinguistic contexts in Experiment 2 did not affect flanker performance. This provides further evidence for the crucial role of language processing during switching to elicit short‐term adaptions on domain‐general conflict monitoring. Overall, our findings add to the previous studies by showing cross‐talk between bilingual language control and domain‐general conflict monitoring when language switching occurs in a comprehension task.
Previous research examining the factors that determine language choice and voluntary switching mainly involved early bilinguals. Here, using picture naming, we investigated language choice and switching in late Dutch–English bilinguals. We found that naming was overall slower in cued than in voluntary switching, but switch costs occurred in both types of switching. The magnitude of switch costs differed depending on the task and language, and was moderated by L2 proficiency. Self-rated rather than objectively assessed proficiency predicted voluntary switching and ease of lexical access was associated with language choice. Between-language and within-language switch costs were not correlated. These results highlight self-rated proficiency as a reliable predictor of voluntary switching, with language modulating switch costs. As in early bilinguals, ease of lexical access was related to word-level language choice of late bilinguals.
Language switching is encountered commonly and inevitably in bilingual society and often induces costs for target language's production. However, for auditory words' comprehension at sentence level, the limited research showed divergent findings. Some research observed comprehension costs when the language of target words was switched with the code of sentential contexts kept constant; but a potential switch advantage was also showed in non-dominant targets' processing when sentential context switches occurred. Additionally, it's well documented that the words' emotional connotations play a key role in both L1 and L2 word comprehension. Therefore, we aimed to explore which switch effect would occur when bilinguals comprehended L1/L2 emotional target nouns in auditory modality at behavioral and neural level through a visual object selection task. Behaviorally, switch related costs occurred in L1 targets' comprehension, whereas advantage effects were found in L2. Moreover, greater switch advantage occurred for positive and negative targets than for neutral ones. Consistently, larger LPC (Late Positive Component) defection was elicited for L2-Switch trials relative to L2-Nonswitch trials and the differences of LPC's amplitude could predict the behavioral advantageous effects of switching in nondominant targets' comprehension, which suggest that language switching lead to deeper re-analyses for emotional words. Taken together, it's suggested that bilinguals can adaptively utilize top-down (sentential prediction) and bottom-up (words' emotional information) cues to access weaker L2 representations.
How does bilingual language control adapt to the cultural context? We address this question by looking at the pattern of switch cost and reversed language dominance effect, which are suggested to separately reflect reactive and proactive language control mechanisms, in the contexts with culturally-neutral pictures (i. e., baseline context) or culturally-biased pictures (i.e., congruent context where culture matched the language to be spoken or incongruent context where culture mismatched the language to be spoken). Results showed an asymmetric switch cost with larger costs for L2 in the congruent context as compared with the baseline and incongruent contexts, but the reversed language dominance effect was not changed across contexts, suggesting that cultural context plays a critical role in modulating reactive but not proactive language control. These findings reveal the dynamic nature of language control in bilinguals and have important implications for the current models of bilingual language control.
Models vary in the extent to which language control processes are domain general. Those that posit that language control is at least partially domain general insist on an overlap between language control and executive control at the goal level. To further probe whether or not language control is domain general, we conducted the first event-related potential (ERP) study that directly compares language-switch costs, as an index of language control, and task-switch costs, as an index of executive control. The language switching and task switching methodology were identical, except that the former required switching between languages (English or Spanish) whereas the latter required switching between tasks (color naming or category naming). This design allowed us to directly compare control processes at the goal level (cue-locked ERPs) and at the task performance level (picture-locked ERPs). We found no significant differences in the switch-related cue-locked and picture-locked ERP patterns across the language and task switching paradigms. These results support models of domain-general language control.
It has been documented that conflict adaptation (conflict resolution in a task enhanced by that in a previous task) exists not only in the same domain but also across different domains with shared cognitive control mechanisms. For the first time, the present study adopted a cross-task adaptive blocked design to examine the relationship between bilingual language control and cognitive control from the perspective of the immediately adjacent, mutual influence on the neural connectivity level. The results showed that the conflict setting induced by previous tasks changed the nodal degrees of the anterior cingulate cortex/presupplementary motor area and the right thalamus, and connectivity strength of shared links between adjacent language and cognitive control tasks. In addition, pre-activation of the cognitive control network affected the transitivity of the successive use of the language control network. These findings not only indicate a cross-task adaptation effect on the neural con-nectivity level, but also provide evidence for similarities in conflict detection and inhibition control between language-specific control and domain-general cognitive control. In addition, our results also suggest that there is only partial overlap between bilingual language control and domain-general cognitive control.
The current longitudinal study investigated how classroom second language (L2) learning modulates the neural correlates of bilingual language control during language production. Chinese college freshmen majoring in English undertook two test sessions (i.e. pre-learning and post-learning) over the course of one year. Specifically, while in the scanner, participants were instructed to name pictures in either their first or second language in response to cues. Behavioral results showed that language switch costs in the post-learning session were reduced as compared to the pre-learning session. fMRI results showed that, compared to the pre-learning session, the connectivity strength between the dorsal anterior cingulate gyrus and the left caudate was increased in the post-learning session. Critically, this increased connectivity strength was correlated with the reduction in language switch costs. These findings suggest that the language control network used during bilingual language production could be modulated by long-term L2 learning in a naturalistic classroom setting. ARTICLE HISTORY
Numerous brain imaging studies identified a domain-general or "multiple-demand" (MD) activation pattern accompanying many tasks and may play a core role in cognitive control. Though this finding is well established, the limited spatial localization provided by traditional imaging methods precluded a consensus regarding the precise anatomy, functional differentiation, and connectivity of the MD system. To address these limitations, we used data from 449 subjects from the Human Connectome Project, with the cortex of each individual parcellated using neurobiologically grounded multimodal MRI features. The conjunction of three cognitive contrasts reveals a core of 10 widely distributed MD parcels per hemisphere that are most strongly activated and functionally interconnected, surrounded by a penumbra of 17 additional areas. Outside cerebral cortex, MD activation is most prominent in the caudate and cerebellum. Comparison with canonical resting-state networks shows MD regions concentrated in the fronto-parietal network but also engaging three other networks. MD activations show modest relative task preferences accompanying strong co-recruitment. With distributed anatomical organization, mosaic functional preferences, and strong interconnectivity, we suggest MD regions are well positioned to integrate and assemble the diverse components of cognitive operations. Our precise delineation of MD regions provides a basis for refined analyses of their functions.
While several reviews provide an in-depth discussion on reactive language control, which is the language control process that is initiated when the non-target language disrupts the selection of target language words, few have touched on proactive language control, which is the language control process implemented as an anticipation of any non-target language interference disrupting the selection of target language words. In the current review, three prominent markers of proactive language control are discussed (i.e., the reversed language dominance effect, language-mixing costs, and the blocked language-order effect). Based on these three markers, it appears that proactive language control can be implemented to mainly restrict interference from the first language during bilingual language production, but is typically absent during bilingual language comprehension. The literature also implies that proactive language control might be partly domain general. With respect to the underlying mechanism of proactive language control, there are some indications that proactive language control relies on inhibition, but no unequivocal evidence has been provided so far.
In the present study, we use a training design in two experiments to examine whether bilingual language switching facilitates two components of cognitive control, namely monitoring and inhibitory control. The results of Experiment 1 showed that training in language switching reduced mixing costs and the anti-saccade effect among bilinguals. In Experiment 2, the findings revealed a greater decrease of mixing costs and a smaller decrease of the anti-saccade effect from pre- to post-training for the language switching training group compared to the second language training group. Overall, the results suggest that extensive exercise in monitoring and inhibitory control in an experimental setting may enhance the corresponding components of cognitive control. We discuss these findings in the context of the relationship between bilingual language control and executive control.
Where and under what conditions do spatial and numerical skills converge and diverge in the brain? To address this question, we conducted a meta-analysis of brain regions associated with basic symbolic number processing, arithmetic, and mental rotation. We used Activation Likelihood Estimation (ALE) to construct quantitative meta-analytic maps synthesizing results from 83 neuroimaging papers (24–31 studies/cognitive process). All three cognitive processes were found to activate bilateral parietal regions in and around the intraparietal sulcus (IPS); a finding consistent with shared processing accounts. Numerical and arithmetic processing were associated with overlap in the left IPS, whereas mental rotation and arithmetic both showed activity in the middle frontal gyri. These patterns suggest regions of cortex potentially more specialized for symbolic number representation and domain-general mental manipulation, respectively. Additionally, arithmetic was associated with unique activity throughout the fronto-parietal network and mental rotation was associated with unique activity in the right
superior parietal lobe. Overall, these results provide new insights into the intersection of numerical and spatial thought in the human brain.
Although there are well-known limitations of the human cognitive system in performing two tasks simultaneously (dual-tasking) or alternatingly (task-switching), the question for a common vs. distinct neural basis of these multitasking limitations is still open. We performed two Activation Likelihood Estimation meta-analyses of neuroimaging studies on dual-tasking or task-switching and tested for commonalities and differences in the brain regions associated with either domain. We found a common core network related to multitasking comprising bilateral intraparietal sulcus (IPS), left dorsal premotor cortex (dPMC), and right anterior insula. Meta-analytic contrasts revealed eight fronto-parietal clusters more consistently activated in dual-tasking (bilateral frontal operculum, dPMC, and anterior IPS, left inferior frontal sulcus and left inferior frontal gyrus) and, conversely, four clusters (left inferior frontal junction, posterior IPS, and precuneus as well as frontomedial cortex) more consistently activated in task-switching. Together with sub-analyses of preparation effects in task-switching, our results argue against purely passive structural processing limitations in multitasking. Based on these findings and drawing on current theorizing, we present a neuro-cognitive processing model of multitasking.
Aims: The present study aimed to investigate the effect of contexts (i.e., non-conflicting context vs. conflicting context) on bilingual language switch costs during language comprehension.
Methodology: Thirty-two unbalance Chinese-English bilinguals completed
a modified comprehension-based language switching task in two
contexts. They made a judgement about the colour meaning of the word.
In the non-conflicting context all words were presented in white ink,
while in the conflicting context the words were printed in an inconsistent
ink colour.
Data and analysis: Reaction time and accuracy data were analyzed using
linear mixed-effects models.
Findings/conclusions: Results showed that the switch costs were larger in
the conflicting context than in the non-conflicting context. Further, in the
non-conflicting context an asymmetrical switch cost with larger costs for
L2 was observed as compared to symmetrical switch costs in the conflicting context.
Originality: This is the first study that indicates bilingual comprehension-
based language control adapts flexibly depending on the context, just as
during bilingual production.
Significance/implications: These findings supported and expanded the
classic adaptive control hypothesis.
How do faces with social-cultural identity affect bilingual language control? We approach this question by looking at the switch cost patterns and reversed language dominance effect, which are suggested to reflect bilingual language control mechanisms, in the absence (i.e., baseline context) or presence of faces with socio-cultural identity (Asian or Caucasian). In separate blocks, the face matched (i.e., congruent context) or mismatched (i.e., incongruent context) the language to be spoken. In addition, cue preparation time was manipulated to be long (Experiment 1) or short (Experiment 2). In both experiments, a unique asymmetric switch cost with larger costs for L2 was observed in the congruent context as compared with the baseline and incongruent contexts. Furthermore, the reversed language dominance effect was not modulated across contexts. These results suggest a critical role of contextual faces in modulating local but not global language control. Thus, bilingual language control changes flexibly within an environment that includes faces with socio-cultural identity.
What is the relationship between bilingual language control (BLC) mechanisms and domain-general executive control (EC) processes? Do these two domains share some of their mechanisms? Here, we take a novel approach to this question, investigating whether short-term language switching training improves non-linguistic task switching performance. Two groups of bilinguals were assigned to two different protocols; one group was trained in language switching (switching-task training group) another group was trained in blocked language picture naming (single-block training group). Both groups performed a non-linguistic and linguistic switching task before (pre-training) and after training (post-training). Non-linguistic and linguistic switch costs decreased to a greater extent for the switching-task training than for the single-block training group from pre- to post-training. In contrast, mixing costs showed similar reductions for both groups. This suggests short-term language switching training can transfer to the non-linguistic domain for certain sub-mechanisms (i.e., switch cost). Thus, there is some overlap of the control mechanisms across domains.
Bilingual speakers are suggested to use control processes to avoid linguistic interference from the unintended language. It is debated whether these bilingual language control (BLC) processes are an instantiation of the more domain-general executive control (EC) processes. Previous studies inconsistently report correlations between measures of linguistic and non-linguistic control in bilinguals. In the present study, we investigate the extent to which there is cross-talk between these two domains of control for two switch costs, namely the n-1 shift cost and the n-2 repetition cost. Also, we address an important problem, namely the reliability of the measures used to investigate cross-talk. If the reliability of a measure is low, then these measures are ill-suited to test cross-talk between domains through correlations. We asked participants to perform both a linguistic- and non-linguistic switching task at two sessions about a week apart. The results show a dissociation between the two types of switch costs. Regarding test–retest reliability, we found a stronger reliability for the n-1 shift cost compared to the n-2 repetition cost within both domains as measured by correlations across sessions. This suggests the n-1 shift cost is more suitable to explore cross-talk of BLC and EC. Next, we do find cross-talk for the n-1 shift cost as demonstrated by a significant cross-domain correlation. This suggests that there are at least some shared processes in the linguistic and non-linguistic task.
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.
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.
Previous studies have demonstrated that language switching in bilinguals can be affected by a number of variables, including the processing context. Here, we used a modified language-switching task combined with a Stroop paradigm, which manipulated the context of the task, to examine the impact of processing context on switch costs. The results of both Experiment 1 and Experiment 2 showed that the switch costs and the level of asymmetry in the switch costs are larger in the conflicting context than in the non-conflicting context, suggesting that the processing context affects the switch costs. In addition, the results of Experiment 2 revealed that individual variances in cognitive control capacity also play a role in the overall magnitude of the switch costs. Critically, processing context effects can be modulated by individual variance in cognitive control capacities. The results of this study are discussed within the framework of classic models of bilingual language control (e.g., the inhibitory control model).
The present study investigated processing differences between young adults who were English monolinguals or English-French bilinguals on a task- and language-switching paradigm. The mechanisms responsible for task switching and language switching were investigated using electrophysiological (EEG) measures. In nonverbal task switching, monolinguals and bilinguals demonstrated equivalent mixing (pure vs. repeat) and switching (repeat vs. switch) costs, but bilinguals were more accurate in the mixed blocks. Bilinguals used a more distributed neural network than monolinguals that captured the nonverbal mixing effect and showed earlier discrimination for the switching effect in the ERPs. In language switching, more distributed networks for bilinguals than monolinguals were found for the switching effect. The scalp distributions revealed more overlap between task switching and language switching for bilinguals than monolinguals. For switch costs, both groups showed P3/LPC modulations in both tasks, but bilinguals showed extended activation to central regions for both switching tasks. For mixing costs, both groups revealed modulations of the N2 but only bilinguals showed extended activation to the occipital region. Overall bilinguals revealed more overlapping processing between task- and language-switching than monolinguals, consistent with the interpretation of integration of verbal and nonverbal control networks during early visual processing for bilinguals and later executive processing for monolinguals.
The present study investigated how language switching experience would modulate the neural correlates of cognitive control involved in bilingual language production. A group of unbalanced Chinese–English bilinguals undertook an 8-day cued picture naming training during which they named pictures in either of their languages based on visually presented cues. Participants' brain activation was scanned before and after the training in the same task. Behavioral results revealed a significant training effect such that switch costs were reduced after training. fMRI results showed that after training, activation of brain areas associated with cognitive control including the anterior cingulated cortex and the caudate was reduced. Besides, the activation reduction in the left dorsal anterior cingulated cortex positively correlated with the reduction in switch costs in response time and this training effect could be transferred to untrained stimuli. These findings suggest that neural correlates of cognitive control, especially that of the conflict monitoring process, in bilingual language production could be modulated by short-term language switching training. Hum Brain Mapp, 2017.
Whereas some models claim that language control is part of more general executive control, others have proposed that there is little overlap between these two processes. To shed light on this controversy, we compared switching effects observed in closely matched language switching and task switching tasks. The correlation analyses showed a positive moderate to strong correlation between the two switching variants in all three experiments. The results further showed that language- and task-switch costs differed although the cues, stimuli, response modality, and the number of response alternatives were identical across the two switching variants (Experiments 1), and when additionally the same linguistic tasks (picture naming/category naming) were used in both switching variants (Experiment 3), at least for the error rates. However, similar language- and task-switch costs were obtained when the same non-linguistic tasks (parity/magnitude) were used (Experiment 2). These results point towards overlapping mechanisms for language control and executive control.
Unlabelled:
For multilingual individuals, adaptive goal-directed behavior as enabled by cognitive control includes the management of two or more languages. This work used magnetoencephalography (MEG) to investigate the degree of neural overlap between language control and domain-general cognitive control both in action and perception. Highly proficient Arabic-English bilingual individuals participated in maximally parallel language-switching tasks in production and comprehension as well as in analogous tasks in which, instead of the used language, the semantic category of the comprehended/produced word changed. Our results indicated a clear dissociation of language control mechanisms in production versus comprehension. Language-switching in production recruited dorsolateral prefrontal regions bilaterally and, importantly, these regions were similarly recruited by category-switching. Conversely, effects of language-switching in comprehension were observed in the anterior cingulate cortex and were not shared by category-switching. These results suggest that bilingual individuals rely on adaptive language control strategies and that the neural involvement during language-switching could be extensively influenced by whether the switch is active (e.g., in production) or passive (e.g., in comprehension). In addition, these results support that humans require high-level cognitive control to switch languages in production, but the comprehension of language switches recruits a distinct neural circuitry. The use of MEG enabled us to obtain the first characterization of the spatiotemporal profile of these effects, establishing that switching processes begin ∼ 400 ms after stimulus presentation.
Significance statement:
This research addresses the neural mechanisms underlying multilingual individuals' ability to successfully manage two or more languages, critically targeting whether language control is uniform across linguistic domains (production and comprehension) and whether it is a subdomain of general cognitive control. The results showed that language production and comprehension rely on different networks: whereas language control in production recruited domain-general networks, the brain bases of switching during comprehension seemed language specific. Therefore, the crucial assumption of the bilingual advantage hypothesis, that there is a close relationship between language control and general cognitive control, seems to only hold during production.
Previous studies have found that lifelong bilingual language experience led to bilingual cognitive control advantage. However, a recent study proposes a new viewpoint that bilingual cognitive control depends on fast language context rather than long-term language experience. Thus, whether the cognitive control components are influenced by language switching context is still an open question. In the current study, two experiments were conducted to investigate the immediate influence of language switch on cognitive control’s different components.
Experiment 1 examined whether language switching context had immediate influence on cognitive control and whether the influences are existed on various components of cognitive control. Thirty participants joined in the Experiment 1 that contains three parts: pre-test part, language switching part and post-test part. In the pre-test part, all participants were asked to complete a “faces task”, which was used to test three components of cognitive control capacity (i.e., response inhibition, interference suppression and cognitive flexibility). Then, they performed a language switch task, in which they were required to name some Arabic numbers from 1 to 8 in Chinese or English according to the cues. When the cue was a green square (or red), participants named the Arabic numbers in Chinese (or English) when the cue was a red square. Finally, participants took part in the “faces task” again in the post-test part. Results showed that language switching context could influence bilinguals’ different components of cognitive control. Specifically, it can facilitate response inhibition and disturb interference suppression, while cannot affect cognitive flexibility. Therefore, response inhibition, interference suppression, and cognitive flexibility were distinct cognitive control components, which had different neural basis.
Experiment 2 was conducted to test two questions. First, we intended to replicate the immediate effect that was observed in Experiment 1. Second, we aimed to explore the causes of the immediate effect. A between-subject design was used in Experiment 2. Ninety-three participants were divided into three groups. Each group performed different language naming tasks. One group named the Arabic numbers in Chinese, while the second group in English. The third group performed language switching task that is the same as Experiment 1. Then, all groups joined in the “faces task.” The results were consistent with Experiment 1, which may suggest that our results are robust. In addition, the results showed that non-proficient Chinese-English bilinguals need more response inhibition because they preferred to use English in language switching. Thus their response inhibition capacity improved by exercises. However, this effect may hinder bilinguals’ interference suppression, while we did not find such effect on cognitive flexibility.
Taken together, results from these two experiments suggested that language switching context had immediate influences on non-proficient bilinguals’ cognitive control ability. Specifically, it could facilitate response inhibition and disturb interference suppression, while no such effect was found on cognitive flexibility. Besides, the results showed that response inhibition, interference suppression, and cognitive flexibility had independent mechanisms. Furthermore, the current study illustrated that the bilingual cognitive control advantages were the results of long-term bilingual language use, which revealed the internal mechanisms of the bilingual advantage.
Key words language switch; language context; components of cognitive control; bilingual advantage
Bilingual speakers may select between two languages either on demand (forced language selection) or on their own volition (free language selection). However, the neural substrates underlying free and forced language selection may differ. While the neural substrates underlying forced language selection have been well-explored with language switching paradigms, those underlying free language selection have remained unclear. Using a modified digit-naming switching paradigm, we addressed the neural substrates underlying free language selection by contrasting free language switching with forced language switching. For a digit-pair trial, Chinese-English bilinguals named each digit in Chinese or English either on demand under forced language selection condition or on their own volition under free language selection condition. The results revealed activation in the frontoparietal regions that mediate volition of language selection. Furthermore, a comparison of free and forced language switching demonstrated differences in the patterns of brain activation. Additionally, free language switching showed reduced switching costs as compared to forced language switching. These findings suggest differences between the mechanism(s) underlying free and forced language switching. As such, the current study suggests interactivity between control of volition and control of language switching in free language selection, providing insights into a model of bilingual language control.
Language switching has been one of the main tasks to investigate language control, a process that restricts bilingual language processing to the target language. In the current review, we discuss the How (i.e., mechanisms) and Where (i.e., locus of these mechanisms) of language control in language switching. As regards the mechanisms of language control, we describe several empirical markers of language switching and their relation to inhibition, as a potentially important mechanism of language control. From this overview it becomes apparent that some, but not all, markers indicate the occurrence of inhibition during language switching and, thus, language control. In a second part, we turn to the potential locus of language control and the role of different processing stages (concept level, lemma level, phonology, orthography, and outside language processing). Previous studies provide evidence for the employment of several of these processing stages during language control so that either a complex control mechanism involving different processing stages and/or multiple loci of language control have to be assumed. Based on the discussed results, several established and new theoretical avenues are considered.
Controlling multiple languages during speech production is believed to rely on functional mechanisms that are (at least partly) shared with domain-general cognitive control in early, highly proficient bilinguals. Recent neuroimaging results have indeed suggested a certain degree of neural overlap between language control and nonverbal cognitive control in bilinguals. However, this evidence is only indirect. Direct evidence for neural overlap between language control and nonverbal cognitive control can only be provided if two prerequisites are met: Language control and nonverbal cognitive control should be compared within the same participants, and the task requirements of both conditions should be closely matched. To provide such direct evidence for the first time, we used fMRI to examine the overlap in brain activation between switch-specific activity in a linguistic switching task and a closely matched nonlinguistic switching task, within participants, in early, highly proficient Spanish-Basque bilinguals. The current findings provide direct evidence that, in these bilinguals, highly similar brain circuits are involved in language control and domain-general cognitive control.
Language control refers to the cognitive mechanism that allows bilinguals to correctly speak in one language avoiding interference from the nontarget language. Bilinguals achieve this feat by engaging brain areas closely related to cognitive control. However, 2 questions still await resolution: whether this network is differently engaged when controlling nonlinguistic representations, and whether this network is differently engaged when control is exerted upon a restricted set of lexical representations that were previously used (i.e., local control) as opposed to control of the entire language system (i.e., global control). In the present event-related functional magnetic resonance imaging study, we investigated these 2 questions by employing linguistic and nonlinguistic blocked switching tasks in the same bilingual participants. We first report that the left prefrontal cortex is driven similarly for control of linguistic and nonlinguistic representations, suggesting its domain-general role in the implementation of response selection. Second, we propose that language control in bilinguals is hierarchically organized with the dorsal anterior cingulate cortex/presupplementary motor area acting as the supervisory attentional system, recruited for increased monitoring demands such as local control in the second language. On the other hand, prefrontal, inferior parietal areas and the caudate would act as the response selection system, tailored for language selection for both local and global control.
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Using fMRI, we conducted two types of property generation task that involved language switching, with early bilingual speakers of Korean and Chinese. The first is a more conventional task in which a single language (L1 or L2) was used within each trial, but switched randomly from trial to trial. The other consists of a novel experimental design where language switching happens within each trial, alternating in the direction of the L1/L2 translation required. Our findings support a recently introduced cognitive model, the ‘hodological’ view of language switching proposed by Moritz-Gasser and Duffau. The nodes of a distributed neural network that this model proposes are consistent with the informative regions that we extracted in this study, using both GLM methods and Multivariate Pattern Analyses: the supplementary motor area, caudate, supramarginal gyrus and fusiform gyrus and other cortical areas.
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 investigated the relationship between language control and executive control by testing three groups of bilinguals (104 participants) and 54 monolinguals in a training and transfer paradigm. Participants practiced either a language or a non-linguistic color/shape switching task and were tested one week later on both tasks. The color-shape task produced significant immediate improvement with training, which was maintained a week later, but exhibited no cross-task transfer effects. In the dominant-language, training effects did not persist after one week, and there were no transfer effects. In the non-dominant language there were significant training effects that lasted a week, and there was also transfer facilitation from prior practice with the color/shape task, which was limited to a reduction in mixing costs. Despite limited transfer, there were significant correlations between tasks in mixing costs for bilinguals, in switching costs for monolinguals, and in intrusion errors for all participants. Finally, the pattern of costs observed for the two tasks exhibited both similarities and differences across participants. These results imply a limited but significant role for executive control in bilingual language control, possibly playing a stronger role in facilitating non-dominant language production and in supporting the ability to monitor response outcomes to avoid errors.
The aim of the present study is two-fold. First, we investigate age-related changes to bilingual language control (bLC) mechanisms across lifespan. Second, we explore the relation between bLC mechanisms and those of the domain-general executive (EC) system by looking at age effects on these two systems. To do so, we compare the performances of the three age groups of bilinguals (young, middle-aged and elderly) in a language switching task to those of non-linguistic switching task. We found an age-related change in the non-linguistic switch cost but not in the language switch cost. Moreover, we did not find any correlation between the magnitudes of the switch costs. Taken together these results indicate that bLC is not affected by age as the EC system is, and interestingly, we add new evidence that the bLC mechanisms are not fully subsidiary to those of the domain-general EC system.
A number of studies have concluded that cognitive control is not fully established until late adolescence. The precise differences in brain function between adults and adolescents with respect to cognitive control, however, remain unclear. To address this issue, we conducted a study in which 185 adolescents (mean age (SD) 14.6 (0.3) years) and 28 adults (mean age (SD) 25.2 (6.3) years) performed a single task that included both a stimulus-response (S-R) interference component and a task-switching component. Behavioural responses (i.e. reaction time, RT; error rate, ER) and brain activity during correct, error and post-error trials, detected by functional magnetic resonance imaging (fMRI), were measured. Behaviourally, RT and ER were significantly higher in incongruent than in congruent trials and in switch than in repeat trials. The two groups did not differ in RT during correct trials, but adolescents had a significantly higher ER than adults. In line with similar RTs, brain responses during correct trials did not differ between groups, indicating that adolescents and adults engage the same cognitive control network to successfully overcome S-R interference or task switches. Interestingly, adolescents with stronger brain activation in the bilateral insulae during error trials and in fronto-parietal regions of the cognitive control network during post-error trials did have lower ERs. This indicates that those mid-adolescents who commit fewer errors are better at monitoring their performance, and after detecting errors are more capable of flexibly allocating further cognitive control resources. Although we did not detect a convincing neural correlate of the observed behavioural differences between adolescents and adults, the revealed interindividual differences in adolescents might at least in part be due to brain development.
The underlying mechanisms that adapt with L2 learning are still poorly understood. The present longitudinal study examined the effects of L2 learning on grey matter structure of Chinese college freshmen majoring in English. Participants were scanned twice, one year apart. Our voxel-based morphometry analyses revealed that gray matter volume (GMV) decreased in the left anterior cingulate cortex (ACC) and right inferior frontal gyrus (IFG) after L2 learning for one year. Critically, these structural adaptations correlated with changes in participants' language control ability across L2 learning. Moreover, age of acquisition of L2 was a significant predictor of volumetric change in the left ACC and L2 proficiency was a significant predictor of volumetric change in the right IFG. Overall, these findings enrich our understanding of the dynamic nature of structural brain adaptations, and the mechanisms these adaptations index, as a function of classroom L2 learning.
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 current longitudinal resting-state functional magnetic resonance imaging study examined changes in language control network after one year of L2 English classroom learning. A group of Chinese college freshmen majoring in English underwent two scans, one before (i.e., Session 1) and one after (i.e., Session 2) the one-year L2 courses. Learners' language control abilities were assessed via a behavioral language switching task. Our graph theory and functional connectivity analyses revealed that with increased exposure to the L2, nodal betweenness in language control areas, such as the dorsal anterior cingulate cortex (dACC), decreased and connectivity between dACC and pre-supplementary motor area (pre-SMA) increased. Critically, these neural changes were correlated with participants' behavioral performance on the language switching task. Taken together, these findings suggest that the language control network in resting brain could be modulated by long-term L2 learning in a naturalistic classroom setting, and that the dACC/pre-SMA complex appears to play a critical role in language control.
Numerous brain imaging studies identified a domain-general or “multiple-demand” (MD) activation pattern accompanying many tasks and may play a core role in cognitive control. Though this finding is well established, the limited spatial localization provided by traditional imaging methods precluded a consensus regarding the precise anatomy, functional differentiation, and connectivity of the MD system. To address these limitations, we used data from 449 subjects from the Human Connectome Project, with the cortex of each individual parcellated using neurobiologically grounded multimodal MRI features. The conjunction of three cognitive contrasts reveals a core of 10 widely distributed MD parcels per hemisphere that are most strongly activated and functionally interconnected, surrounded by a penumbra of 17 additional areas. Outside cerebral cortex, MD activation is most prominent in the caudate and cerebellum. Comparison with canonical resting-state networks shows MD regions concentrated in the fronto-parietal network but also engaging three other networks. MD activations show modest relative task preferences accompanying strong co-recruitment. With distributed anatomical organization, mosaic functional preferences, and strong interconnectivity, we suggest MD regions are well positioned to integrate and assemble the diverse components of cognitive operations. Our precise delineation of MD regions provides a basis for refined analyses of their functions.
When switching languages, bilinguals recruit a language control network that overlaps with brain regions known to support general cognitive control, but it is unclear whether these same regions are recruited in passive comprehension of language switches. Using fMRI with a blocked design, 24 Spanish-English bilinguals silently read 36 paragraphs in which the default language was Spanish or English, and that had either (1) no switches, (2) function word switches or (3) content word switches. Relative to no switches, function switches activated the right IFG, bilateral MFG, and left IPL/SMG. In contrast, switching on content words produced limited neural switching costs observed only in the left IFG. Switching into the dominant language was more costly in the right SMG than switching into the nondominant language, and neural switching costs were correlated with switching costs in the dominant language in cued picture-naming. Seemingly passive reading comprehension involves brain regions known to support cognitive control in active switching during production, possibly reflecting the operation of a modality-general switch mechanism.
Notwithstanding rising interest, a coherent picture of the brain's representation of two languages has not yet been achieved. In the present meta-analysis we analysed a large number of functional neuroimaging studies focusing on language processing in bilinguals. We used activation likelihood estimation (ALE) to enucleate activation areas involved in bilingual processing and control of different types of linguistic knowledge - lexico-semantics, grammar, phonology - in L1 and L2. Results show that surprisingly, compared to L2, lexico-semantic processing in L1 involves a widespread system of cortico-subcortical regions, especially when L2 is acquired later in life. By contrast, L2 processing recruits regions exceeding the L1 semantic network and relating to executive control processes. Only few regions displayed selective activation for grammar and phonology. Analyses of language switching highlight a functional overlap between domain-general and bilingual language control networks. Collectively, our findings point to a shared neural network for L1 and L2 with few differences depending on the linguistic level. The emerging picture identifies under-investigated issues, offering clear directions for future research.
This chapter reviews current knowledge about the relationship between language control and executive control (EC) mechanisms in bilingual speakers. The most common strategy to assess the relationship between the two domains of control is to compare people's performance on control tasks that involve linguistic and non‐linguistic processes. The chapter reviews studies that have tested bilingual language control (BLC) and EC in the same population of bilingual speakers by focusing on neuroimaging data and cognitive and language deficits following brain damage. One critical point in studying the cross‐talk between language and EC in bilinguals is the complexity of the concept of control in these two domains. In recent years, the issue of EC deficits amongst bilingual patients with aphasia has attracted interest, especially amongst speech pathology researchers. In sum, aphasia studies that have explored the cross‐talk between BLC and EC have yielded mixed findings, with some indications favouring an incomplete overlap between the two systems.
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.
Given the increasing number of neuroimaging publications, the automated knowledge extraction on brain-behavior associations by quantitative meta-analyses has become a highly important and rapidly growing field of research. Among several methods to perform coordinate-based neuroimaging meta-analyses, Activation Likelihood Estimation (ALE) has been widely adopted. In this paper, we addressed two pressing questions related to ALE meta-analysis: i) Which thresholding method is most appropriate to perform statistical inference? ii) Which sample size, i.e., number of experiments, is needed to perform robust meta-analyses? We provided quantitative answers to these questions by simulating more than 120,000 meta-analysis datasets using empirical parameters (i.e., number of subjects, number of reported foci, distribution of activation foci) derived from the BrainMap database. This allowed to characterize the behavior of ALE analyses, to derive first power estimates for neuroimaging meta-analyses, and to thus formulate recommendations for future ALE studies. We could show as a first consequence that cluster-level family-wise error (FWE) correction represents the most appropriate method for statistical inference, while voxel-level FWE correction is valid but more conservative. In contrast, uncorrected inference and false-discovery rate correction should be avoided. As a second consequence, researchers should aim to include at least 20 experiments into an ALE meta-analysis to achieve sufficient power for moderate effects. We would like to note, though, that these calculations and recommendations are specific to ALE and may not be extrapolated to other approaches for (neuroimaging) meta-analysis.
We explored the overlap between bilingual language control (bLC) and domain-general executive control (EC) by focusing on inhibitory control processes. We tested 62 bilinguals in linguistic and non-linguistic switching tasks for two types of costs, such as the n-1 shift cost and the n-2 repetition cost. In order to explore the involvement of inhibitory control in bLC and EC, we assessed the pattern of switch costs in the two tasks and then we correlated them between tasks. Results showed reduced n-2 repetition costs as compared to n-1 shift costs in the linguistic task only, suggesting that small amount of inhibition were deployed when switching between languages. Importantly, neither the n-1 shift costs nor the n-2 repetition costs were correlated between tasks. These results, supported by additional evidence from the ex-Gaussian analysis, suggest that inhibitory control is differently involved in bLC and in EC.
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.
The basal ganglia are critically involved in language control (LC) processes, allowing a bilingual to utter correctly in one language without interference from the non-requested language. It has been hypothesized that the neural mechanism of LC closely resembles domain-general executive control (EC). The purpose of the present study is to investigate the integrity of bilingual LC and its overlap with domain-general EC in a clinical population such as individuals with Parkinson's disease (PD), notoriously associated with structural damage in the basal ganglia.We approach these issues in two ways. First, we employed a language switching task to investigate the integrity of LC in a group of Catalan–Spanish bilingual individuals with PD, as compared to a group of matched healthy controls. Second, to test the relationship between domain-general EC and LC we compared the performances of individuals with PD and healthy controls also in a non-linguistic switching task. We highlight that, compared to controls, individuals with PD report decreased processing speed, less accuracy and larger switching costs in terms of RT and errors in the language switching task, whereas in the non-linguistic switching task PD patients showed only increased switching cost in terms of errors. However, we report a positive correlation between the magnitudes of linguistic and non-linguistic mixing costs in individuals with PD. Taken together, these results support the notion of a critical role of the basal ganglia and connected structures in LC, and suggest a possible link between LC and domain-general EC.
Significance
One of the oldest debates in cognitive neuroscience concerns the degree of functional specialization present in the human brain. Prior work has discovered several highly specialized components dedicated to particular mental functions, like face recognition or motion perception. However, our cognitive versatility suggests the additional existence of more general-purpose machinery. Building on prior neuroimaging evidence, along with neurophysiological evidence from non-human primates, we searched for such domain-general brain regions in humans. Seven diverse demanding cognitive tasks produced overlapping activation at the individual-subject level in a number of frontal and parietal brain regions. Thus, human cognition arises from hardware that includes not only specialized components, but also very general-purpose ones that plausibly enable us to solve novel problems.