Verbal working memory of Korean–English bilinguals: An fMRI study

Abstract

This study investigated whether different brain areas are involved during working memory tasks related to first (L1) and second (L2) languages. Functional magnetic resonance imaging (fMRI) was performed on 24 bilingual native Korean speakers who acquired English as their L2 after the age of 12. Their L2 proficiency ranged from low to moderate. The images were acquired while the participants performed word recognition tasks in their L1 and L2. Different areas of activation were identified for Korean and English verbal working memory (KVWM and EVWM) tasks and more right hemisphere activation was found during L2 processing than during L1 processing. Direct comparison between activation during L1 and L2 processing revealed that additional hemisphere regions were recruited during the EVWM condition than during the KVWM condition, but no significantly greater activation occurred during the KVWM task than during the EVWM task. This pattern of results indicates that distinct brain areas are associated with L1 and L2 processing, and more diverse and right hemisphere areas are activated during L2 processing compared to L1 processing among low to moderately proficient late bilinguals. The activated areas during L2 processing relative to L1 processing were the left precuneus (BA 7), right superior parietal lobule (BA 7), left middle occipital gyrus (BA 19), and left cerebellum, suggesting that participants might rely more on visual cues and visual processing for word recoding and visual analysis during L2 processing than during L1 processing. It is also plausible that participants engaged in attention-based rehearsal during L2 processing.