Neuroanatomical markers of individual differences in native and non-native vowel perception

Although most human beings experience no difficulty in perceiving their native language, strong individual differences are observed for certain foreign phonemic contrasts. Diaz, Baus, Escera, Costa, and Sebastian-Galles (2008, Brain potentials to native phoneme discrimination reveal the origin of individual differences in learning the sounds of a second language. Proceedings of the National Academy of Sciences of the United States of America, 105, 16083–16088) reported a correlation between eventrelated potential (ERP) responses to native and non-native vowels in a group of early and highly-skilled bilinguals. In the present study, we compared the brain morphology of two groups of bilinguals who were equally proficient in their second language but differed in their perception of both native and non-native vowels. A whole brain, voxel-based morphometry analysis (VBM) revealed larger white matter volume in the right insulo/frontoopercular region in individuals who exhibited poorer perceptual discrimination of native and non-native vowels. As the volume of it, Universitat Pompeu Fabra, C/ Roc Boronat 138 – Room 55.126, 08018