Language context tunes brain network for language control in bilingual language production

When bilinguals intend to speak in their first (L1) or second language (L2) according to the environment, a brain network involving cortical-subcortical regions is recruited to resolve cross-language interference. Research has found that the activation of these brain regions varies with language contexts. However, previous studies have not yet examined adaptive changes in the interactions of brain regions for different language contexts. To address this gap, we adopted extended unified structural equation modeling (euSEM) to identify the connectivity patterns of the bilingual control network. Twenty-one unbalanced Chinese-English bilinguals were instructed to name pictures in L1-single, L2-single, and dual-language contexts while undergoing functional magnetic resonance imaging (fMRI). We found that unbalanced bilinguals relied on a more functional integrated brain network, which was reflected by clearer core-periphery structures and increased global efficiency, in dual-language and L2-single contexts compared to L1-single context. Furthermore, the pattern of brain connectivity in the dual-language context was more similar to that in the L1-single context than the L2-single context. More importantly, we found more similarities between the connectivity patterns of dual-language and L1-single contexts in bilinguals with lower inhibitory control abilities. These findings provide the first connectivity evidence for the effect of language context on the bilingual language control network, which inhibits the base language and underpins bilinguals' change along the monolingual-bilingual mode continuum.