AoA-L2 and Usage-L2 modulate the functional neuroplasticity of the subcortex

Previous studies revealed structural differences in subcortical regions between monolinguals and bilinguals; however, whether the functional neuroplasticity of the subcortex is modulated by different bilingual experiences remains unclear. Here, we examined the effect of age of second language acquisition (AoA-L2) and usage of L2 (Usage-L2) on subcorto-cortical and intra-subcortical functional connectivity (FC) in bilinguals by using resting-state fMRI data. The relations between brain measurements and bilingual experiences were revealed by using multiple regression analysis. We found that increased AoA-L2 was mainly related to decreased subcortical FC involving the anterior thalamus, basal ganglia, and hippocampus. Increased Usage-L2 at home was mainly associated with decreased subcortical FC of the amygdala, globus pallidus, hippocampus, and nucleus accumbens. The FC of these subcortical regions displayed a positive relation with Usage-L2 in social settings. These findings reveal that bilingual experiences modulate the functional neuroplasticity of the subcortex in different ways.