Accumulating evidence has demonstrated that bilingual experience shapes the intrinsic functional organization of the brain. However, the findings from different studies remain fragmented. This review synthesizes resting-state functional magnetic resonance imaging (fMRI) studies examining how distinct dimensions of bilingual experience, including the age of L2 acquisition (AoA-L2), L2 proficiency (PL-L2), and usage of L2 (Usage-L2), modulate the resting-state functional connectivity (RSFC) and the intrinsic organization of the functional network. Earlier AoA-L2 is associated with stronger RSFC involving the language, attentional, and subcortical systems, whereas later acquisition is linked to compensatory increases in control and cerebellar-subcortical circuits. The evidence for PL-L2 indicates that bilinguals with higher proficiency exhibit increased RSFC within attentional, subcortical, and cerebellar networks, along with a more efficient and integrated organization of the whole-brain functional network. The frequency and contextual diversity of real-world Usage-L2 dynamically reshape intrinsic connectivity, with socially diverse language engagement enhancing cross-network integration in control, subcortical, and cerebello-cortical circuits, whereas routine home use is linked to more reduced or localized connectivity patterns. The current evidence reveals meaningful but fragmented patterns linking bilingual experience to intrinsic functional connectivity, largely due to conceptual inconsistencies, limited linguistic diversity, small samples, methodological heterogeneity, and the scarcity of longitudinal or multimodal designs. This review identifies seven priorities for future research to address these constraints and move toward a more unified account of bilingual neuroplasticity: establishing standardized and multidimensional measures of bilingual experience; expanding linguistic and sociocultural diversity; increasing statistical power and reproducibility; implementing longitudinal, training-based, and experience-sampling designs; harmonizing resting-state preprocessing and analytical pipelines; modeling nonlinear and interactive brain-experience relationships; and integrating multimodal neuroimaging to elucidate mechanistic pathways. Advances in these directions will enable the field to move beyond descriptive findings toward explanatory models that illuminate how different dimensions of bilingual experience dynamically reorganize the intrinsic functional architecture of the brain.
Jiang et al. (Tue,) studied this question.