Neural representations of phonological information in bilingual language production.

Previous research has explored the neural mechanisms of bilinguals' language production, but most studies focused on neural mechanisms of cognitive control during language production. Therefore, it is unclear which brain regions represent lexical information (especially phonological information) during production and how they are affected by language context. To address those questions, we used representational similarity analysis to explore neural representations of phonological information in native (L1) and second languages (L2) in the single- and mixed-language contexts, respectively. Results showed that Chinese-English bilinguals behaviorally performed worse and exhibited more activations in brain regions associated with language processing and cognitive control in the mixed-language context relative to the single-language context. Further representational similarity analysis revealed that phonological representations of L1 were detected in the left pars opercularis, middle frontal gyrus, and anterior supramarginal gyrus, while phonological representations of L2 were detected in the bilateral occipitotemporal cortex regardless of the target language. More interestingly, robust phonological representations of L1 were observed in brain areas related to phonological processing during L2 production regardless of language context. These results provide direct neuroimaging evidence for the nonselective processing hypothesis and highlight the superiority of phonological representations in the dominant language during bilingual language production.