Free Language Selection in the Bilingual Brain: An Event-Related fMRI Study

Enhancing Access Through Language-Tailored Approach in Telehealth and Veterans Video Connect: Traumatic Brain Injury (TBI) Veterans Satisfaction Assessment

INTRODUCTION

Traumatic brain injury (TBI) can impact language processing, necessitating language-tailored approaches. Telehealth may expand rural Veterans' access but has unknown feasibility for language preferences. This study explored telehealth/Veterans Video Connect satisfaction for Spanish/English TBI screening.

MATERIALS AND METHODS

The study was approved by the VA Caribbean Healthcare System Institutional Review Board and the Research and Development Committee. Mixed methods evaluated telehealth satisfaction in Veterans receiving TBI assessments from October 2021 to October 2023. Surveys included the 16-item Clinical Video Telehealth (CVT) questionnaire on communication, technical factors, coordination, and overall satisfaction, and the 21-item Telemedicine Satisfaction and Usefulness Questionnaire (TSUQ) examining usefulness, ease of use, manners, quality, and satisfaction. Mean domain/item scores were calculated among 57 Veterans, 12 English, and 45 Spanish-speaking. Semi-structured interviews also elicited user experiences from 4 providers and 5 Veterans. Transcripts underwent qualitative coding for themes using Atlas.ti.8.

RESULTS

On CVT (0-5 scale), overall satisfaction averaged 4.50 (English) and 4.69 (Spanish). Lowest scoring item for English users was easy video connection (4.25), while unclear expectations had the lowest Spanish score (3.60). For TSUQ, overall mean scores were 4.50 (English) and 4.67 (Spanish), with improved health post-telehealth having the lowest average (English 3.33, Spanish 3.67). Qualitatively, Veterans and providers noted strengths like access and communication but weaknesses around connectivity, care delays, and privacy. Differences emerged regarding convenience (Veterans) versus operational barriers (providers). There was a strong positive correlation for Spanish surveys and a moderate correlation for English surveys (r = 0.71 Spanish surveys, r = 0.69 English surveys) between TSUQ and CVT for individual respondents.

CONCLUSIONS

Patients conveyed positive experiences, but qualitative data revealed actionable targets for optimization like infrastructure and coordination improvements. Key limitations include small samples and lack of comparison to in-person care. Still, high satisfaction coupled with specific user feedback highlights telehealth's potential while directing enhancements. The results found high Veteran satisfaction with Spanish/English TBI telehealth, but mixed methods illuminated salient domains for better accommodating user needs, particularly regarding logistics and technology. Rigorously integrating experiences with metrics over expanded diverse samples and modalities can further guide refinements to enhance telehealth with a language-tailored approach.

Tracking Components of Bilingual Language Control in Speech Production: An fMRI Study Using Functional Localizers

When bilingual speakers switch back to speaking in their native language (L1) after having used their second language (L2), they often experience difficulty in retrieving words in their L1. This phenomenon is referred to as the L2 after-effect. We used the L2 after-effect as a lens to explore the neural bases of bilingual language control mechanisms. Our goal was twofold: first, to explore whether bilingual language control draws on domain-general or language-specific mechanisms; second, to investigate the precise mechanism(s) that drive the L2 after-effect. We used a precision fMRI approach based on functional localizers to measure the extent to which the brain activity that reflects the L2 after-effect overlaps with the language network (Fedorenko et al., 2010) and the domain-general multiple demand network (Duncan, 2010), as well as three task-specific networks that tap into interference resolution, lexical retrieval, and articulation. Forty-two Polish-English bilinguals participated in the study. Our results show that the L2 after-effect reflects increased engagement of domain-general but not language-specific resources. Furthermore, contrary to previously proposed interpretations, we did not find evidence that the effect reflects increased difficulty related to lexical access, articulation, and the resolution of lexical interference. We propose that difficulty of speech production in the picture naming paradigm-manifested as the L2 after-effect-reflects interference at a nonlinguistic level of task schemas or a general increase of cognitive control engagement during speech production in L1 after L2.

Cognitive and neural mechanisms of voluntary versus forced language switching in Chinese-English bilinguals: an fMRI study

The ecological validity of bilingual code-switching has garnered increasing attention in recent years. Contrary to traditional studies that have focused on forced language switching, emerging theories posit that voluntary switching may not incur such a cost. To test these claims and understand differences between forced and voluntary switching, the present study conducted a systematic comparison through both behavioral and neural perspectives. Utilizing fMRI alongside picture-naming tasks, our findings diverge from prior work. Voluntary language switching not only demonstrated switching costs at the behavioral level but also significantly activated brain regions associated with inhibitory control. Direct comparisons of voluntary and forced language switching revealed no significant behavioral differences in switching costs, and both shared several common brain regions that were activated. On the other hand, a nuanced difference between the two types of language switching was revealed by whole-brain analysis: voluntary switching engaged fewer language control regions than forced switching. These findings offer a comprehensive view of the neural and behavioral dynamics involved in bilingual language switching, challenging prior claims that voluntary switching imposes no behavioral or neural costs, and thus providing behavioral and neuroimaging evidence for the involvement of inhibitory control in voluntary language switching.

Inhibitory control training reveals a common neurofunctional basis for generic executive functions and language switching in bilinguals

BACKGROUND

The neural networks underpinning language control and domain-general executive functions overlap in bilinguals, but existing evidence is mainly correlative. Here, we present the first neurofunctional evidence for a transfer effect between (domain-general) inhibitory control and language control through training. We trained Chinese-English bilinguals for 8 days using a Simon task taxing the inhibitory control system, whilst an active control group was trained with a color judgment task that does not tax the inhibitory control system. All participants performed a language-switching task before and after training. It has been suggested that the activity of the left DLPFC was associated with domain-general top-down cognitive control (Macdonald et al. Science 288: 1835-1838, 2000) and bilingual language control (Wang et al. Neuroimage 35: 862-870, 2007). In addition, the dACC was closely related to the conflict detection (Abutalebi et al. Cereb Cortex 18:1496-1505, 2008). Last, the activity of the left caudate has been linked with lexical selection (Abutalebi et al. Cereb Cortex 18:1496-1505, 2008), especially the selection of the weak language (Abutalebi et al. Cortex 49: 905-911, 2013). Therefore, we focused on these three regions of interest (ROIs) where neural changes associated with transfer were expected to occur.

RESULTS

The results showed a negative correlation between changes in activation levels in the left dorsolateral prefrontal cortex (DLPFC) and changes in the switch cost magnitude in the language-switching task in the training group but not in the control group, suggesting that the DLPFC plays a critical role in the transfer effect from domain-general executive functions to language control. However, there was no measurable effect in the anterior cingulate cortex or left caudate nucleus, suggesting that the inhibitory control training increased the neural efficiency for language production in bilinguals in terms of attention shifting and conflict resolution, but the training did not affect conflict detection and lexical selection.

CONCLUSION

These findings showed how cognitive training evidence can help establish a causational link between the neural basis of domain-general executive functions and language control in bilinguals.

Bilingualism and domain-general cognitive functions from a neural perspective: A systematic review

A large body of research has indicated that bilingualism - through continual practice in language control - may impact cognitive functions, as well as relevant aspects of brain function and structure. The present review aimed to bring together 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 findings 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 effect of lexical accessibility on Spanish-English intra-sentential codeswitching

Bilingual speakers sometimes codeswitch, or alternate between languages, in a single utterance. We investigated the effect of lexical accessibility of words, defined as the ease with which a speaker retrieves and produces a word, on codeswitching in Spanish-English bilinguals. We first developed a novel sentence-production paradigm to elicit naturalistic codeswitches in the lab. We then predicted items on which speakers were more or less likely to codeswitch as a consequence of the relative lexical accessibility of those items' labels across a speaker's two languages. In a Spanish sentence-production task, greater lexical accessibility in English was associated with an increased rate of codeswitching and longer speaking durations on trials on which speakers codeswitched, as well as on trials on which speakers did not codeswitch. Codeswitches were more frequent on trials where speakers likely experienced more competition from the other-language label, suggesting that codeswitching may be a tool that bilingual speakers use to alleviate difficulty associated with cross-language lexical competition. Given findings that comprehenders are able to learn lexical distributions and subtle acoustic cues to predict upcoming codeswitches, the present work suggests that demands on speakers during language production may play a role in explaining how those patterns come to exist in the language environment.

Semantic and attentional networks in bilingual processing: fMRI connectivity signatures of translation directionality

Comparisons between backward and forward translation (BT, FT) have long illuminated the organization of bilingual memory, with neuroscientific evidence indicating that FT would involve greater linguistic and attentional demands. However, no study has directly assessed the functional interaction between relevant mechanisms. Against this background, we conducted the first fMRI investigation of functional connectivity (FC) differences between BT and FT. In addition to yielding lower behavioral outcomes, FT was characterized by increased FC between a core semantic hub (the left anterior temporal lobe, ATL) and key nodes of attentional and vigilance networks (left inferior frontal, left orbitofrontal, and bilateral parietal clusters). Instead, distinct FC patterns for BT emerged only between the left ATL and the right thalamus, a region implicated in automatic relaying of sensory information to cortical regions. Therefore, FT seems to involve enhanced coupling between semantic and attentional mechanisms, suggesting that asymmetries in cross-language processing reflect dynamic interactions between linguistic and domain-general systems.