Differential cortical responses in second language learners to different vowel contrasts

Near-infrared spectroscopy was used to measure hemodynamic responses in Korean subjects learning Japanese as a second-language to Japanese phonemic contrasts that are either phonologically distinctive or non-distinctive in their first-language. These results were compared with those of Japanese native listeners reported previously. Unlike the results observed in the Japanese subjects, the Korean subjects did not show category-specific neural responses to a durational contrast that is non-distinctive in their first-language. The /a-e/ contrast elicited the larger response in the left auditory area, consistent with the results of the Japanese. These phoneme-dependent responses imply that the neuronal networks subserving the first and second-languages are either shared or exclusive according to the mutual relationship between the phonemic properties of the first and second-languages.