Bilingual language processing relies on shared semantic representations that are modulated by each language

Billions of people throughout the world are bilingual and can extract meaning from multiple languages. While some evidence suggests that there is a shared system in the human brain for processing semantic information from different languages, other evidence suggests that semantic processing is to some degree distinct between languages. We conducted a study to determine how semantic representations in the brains of bilinguals can support both shared and distinct processing for different languages. Functional magnetic resonance imaging (fMRI) was used to record brain responses while participants who are fluent in both English and Chinese read several hours of natural narratives in each language. These data were then used to specifically and comprehensively compare semantic representations between the two languages. First, we show that semantic representations are largely shared between languages. Second, we show that there are finer-grained differences that systematically alter how the same meaning is represented between different languages. Our results suggest that for bilinguals, semantic brain representations are shared across languages but modulated by each language. These results reconcile current competing theories of bilingual language processing.