The brain activity flow in language and cognitive control networks underlying second language proficiency

Abstract It remains unclear how language and cognitive control networks interact to support second language (L2) proficiency in the bilingual brain. Our study used gradient network and dynamic causal modelling (DCM) to investigate the brain activity flow in these two brain networks underlying L2 proficiency with sixty-one Chinese-English bilinguals. We found that the gradient values of the right calcarine gyrus and the left supramarginal gyrus were positively correlated with L2 proficiency. However, multivariate pattern and region-of-interest analyses suggested that L2 proficiency may not significantly modulate the brain activity flow of these two networks in global network gradients. Meanwhile, DCM findings demonstrated that L2 proficiency development increased inhibitory effects from the language network to the cognitive control network, indicating that L2 learning would modulate the cognitive control system. In summary, our study provides further insights into how language and cognitive control networks interact to establish a smooth bilingual system underlying L2 proficiency.