Decoding how cerebellum represents bilingual language information

While the cerebellum is increasingly recognized for its involvement in language processing, the nature and extent of how it represents bilingual language information remain poorly understood. Crucially, it is unknown whether the cerebellum encodes bilingual language information solely through cerebellar activities or primarily through cortico-cerebellar interactions, and whether the information richness of those representations varies across languages. Here we used functional magnetic resonance imaging (fMRI) to investigate how the cerebellum flexibly adapts its contribution during narrative comprehension in proficient Chinese-English bilinguals. The participants performed identical tasks in their first (L1) and second language (L2). We revealed that cerebellum exhibited enhanced informativeness (information richness) through cortico-cerebellar interaction during bilingual narrative processing. Notably, this informativeness was significantly greater in L2. Cross-language differences in the cortico-cerebellar interactions-loaded informativeness were primarily mediated by functional interactions related to the cortical default mode network (DMN) and the cerebellar sensorimotor network (SMN). These findings suggest that the cerebellum dynamically modulates its functional coupling with the cortical networks to support language-specific processing. The semantic dimensions of the narrative stimuli account for the informativeness of cortico-cerebellar interactions in both languages. Our study provides novel insights and a methodological framework for understanding cerebellum's role in bilingual language processing.