Bilingual experience shapes brain connectivity in childhood

Abstract How bilingualism impacts the brain networks that support language and cognitive control in childhood is largely unknown. Here we used diffusion-weighted and resting-state functional MRI to assess structural and functional connectivity in 36 English–Greek bilinguals and 17 English monolinguals aged 8 to 10 years. We examined language networks (arcuate and inferior fronto-occipital fasciculus microstructure; fronto-temporal functional connectivity) as well as domain-general networks involved in attention and cognitive control (superior longitudinal fasciculus microstructure; default mode network; salience network; fronto-parietal control network; striatal network functional connectivity). In the bilingual group, greater bilingual engagement was associated with enhanced default-mode and fronto-parietal functional connectivity. Earlier bilingual exposure was associated with higher superior longitudinal fasciculus microstructure. There were no associations between bilingual experience measures and language network metrics. Overall, we reveal that immersive bilingualism leaves neural signatures in the developing brain, mainly by shaping the intrinsic connectivity of domain-general networks.