Neural mechanisms of extreme language control in bimodal bilinguals

Abstract: Multilingual language control is a cognitive mechanism for selecting and using the appropriate language while avoiding interference from further acquired languages, depending on the communicative need. A vast body of research on language control and bilingualism has shown that language control is a complex and demanding process that shares overlapping brain regions engaged in domain-general executive control functions. In addition, evidence shows that language control is employed regardless of modality differences between languages, such as bimodal bilingualism, which involves acquiring and using sign and spoken languages. However, further work is needed to elucidate the neural underpinnings of language control utilized in bimodal bilingualism (or multilingualism), which involves acquiring and using sign and spoken languages. To investigate this, we used functional magnetic resonance imaging (fMRI) to examine the neural basis of a simultaneous interpreting (SI) task in early Turkish-Turkish Sign Language (TID) bimodal bilinguals (N = 20 recruited, 17 analysed). SI  in pairs of oral languages has been a focus of investigation due to the claim that it requires “extreme language control”, since it poses an unusual language control demands – unlike most communicative contexts, which are monolingual and consequently require the suppression of the language (or languages) not in use, SI requires simultaneous access to two languages: the language to be interpreted (source language), and the language that must be produced (target language).

The investigation included two interpreting directions: from Turkish to TID and TID to Turkish, and control conditions: TID shadowing, Turkish shadowing, as well as passive observation of TID and passive listening to Turkish. Our analyses revealed overlapping activations in motor regions, including the precentral gyrus and insula, for shadowing in Turkish and TID. However, we report distinct neural mechanisms employed in SI in two directions: When interpreting from Turkish to TID, domain-general structures such as the precentral gyrus and cerebellum were engaged, and conversely, interpreting from TID to Turkish involved activation of the posterior part of the superior temporal gyrus. The findings provide new insights into the neural mechanisms of bimodal language control, contributing to our understanding of how bilingual individuals manage and switch between languages across different modalities. Overall, we discuss the complex processes involved in bilingual language control, particularly in bimodal bilingualism, and lay the groundwork for further exploration in this field.

Le mardi 21 avril 2026 à 11h00 / salle Alain Roure, LMA

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