The Effect of AoA-L2 on Functional Network Dynamics in Bilinguals

Bilingual experiences have been shown to induce functional and structural neuroplasticity, yet how the age of second language acquisition (AoA-L2) shapes the functional network dynamics remains unclear. In this study, we investigated the effect of AoA-L2 on the temporal properties of dynamic functional connectivity (dFC) states and the variability of dFC and functional network topological organization in bilinguals by using resting-state fMRI data. Compared with late bilinguals, early bilinguals spent a greater proportion of time in sparsely connected states within the subcortical and ventral attention networks and exhibited greater variability of dFC involving multiple systems, including auditory, frontoparietal, subcortical, and attentional networks. In addition, the L2 proficiency was positively associated with the variability of dFC between the cingulo-opercular and default mode networks but negatively associated with the variability of dFC between the frontoparietal and visual networks. These findings suggest that AoA-L2 modulates the temporal flexibility of functional network organization, providing novel perspectives on the functional neuroplasticity induced by bilingualism.