Effects of short-term second language learning on the development of individual semantic networks in written and spoken language

Previous studies have primarily focused on the relationship between native language (L1) and second language (L2) in the brain, specifically in one language modality, such as written or spoken language. However, there is limited research on how L2 proficiency impacts both modalities. This study aimed to investigate the functional networks involved in reading and speech comprehension for both L1 and L2, and observe changes in these networks as L2 proficiency improves. The dataset used in this study was obtained from a previous research conducted by Gurunandan et al., which involved Spanish-English bilingual participants undergoing a threemonth English training program. Participants underwent fMRI scanning and performed a semantic animacy judgment task in both spoken and written language before and after training. Through analysis, distinct neural networks associated with spoken and written language were found between individuals' L1 and L2, both before and after training. Moreover, as L2 proficiency improved, the spoken and written networks for L2 remained distinct from those of the L1. These findings suggest that short-term L2 learning experiences can modify neural networks, but may not be enough to achieve native-like proficiency, supporting the accommodation hypothesis. These results have important implications for language learning and education, indicating that additional shortterm training and exposure alone may not bridge the gap between L1 and L2 processing networks.