Structural brain changes as a function of second language vocabulary training: Effects of learning context.

Recent research indicates that learning a second language (L2) results in both functional and structural brain changes. However, few studies have examined whether structural brain changes vary as a function of the context in which L2 learning takes place. The current study examines changes in cortical thickness (CT) and gray matter volume (GMV) in response to short-term L2 vocabulary learning. In particular, we compared structural changes for learning with paired picture-word (PW) association versus learning within virtual environments (VE) and non-trained controls. Both L2 training groups learned the same 90 Mandarin Chinese nouns across 7 training sessions over approximately 20 days. Our results show (a) CT and GMV increased in regions implicated in a language control network for both L2 training groups, and (b) participants in different learning contexts may rely on different structures within this language control network. In particular, CT in the right IFG was associated with L2 training performance for the PW group, whereas CT in the right IPL showed a positive correlation with L2 training performance for the VE group. Our findings indicate that short-term L2 training leads to changes in brain structure, which vary based on L2 learning contexts and individual differences in cognitive ability.