Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Department of Linguistics and Philosophy, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 32-D80802139, USA.
Sci Rep. 2021 Mar 31;11(1):7296. doi: 10.1038/s41598-021-86710-4.
The neuroscientific foundation of multilingualism, a unique cognitive capacity, necessitates further elucidation. We conducted an fMRI experiment to evaluate the acquisition of syntactic features in a new language (Kazakh) for multilinguals and bilinguals. Results showed that the multilinguals who were more proficient in their second/third languages needed fewer task trials to acquire Kazakh phonology. Regarding group differences, the reduction in response times during the initial exposure to Kazakh were significantly larger for the multilinguals than the bilinguals. For the multilinguals, activations in the bilateral frontal/temporal regions were maintained at a higher level than the initial level during subsequent new grammar conditions. For the bilinguals, activations in the basal ganglia/thalamus and cerebellum decreased to the initial level each time. Direct group comparisons showed significantly enhanced activations for the multilinguals in the left ventral inferior frontal gyrus. These results indicate that both syntax-related and domain-general brain networks were more enhanced for the multilinguals. We also unexpectedly observed significant activations in the visual areas for the multilinguals, implying the use of visual representation even when listening to speech sounds alone. Because the multilinguals were able to successfully utilize acquired knowledge in an accumulated manner, the results support the cumulative-enhancement model of language acquisition.
多语言能力的神经科学基础是一种独特的认知能力，需要进一步阐明。我们进行了一项 fMRI 实验，以评估多语言者和双语者对新语言（哈萨克语）句法特征的习得。结果表明，第二/第三语言能力更强的多语言者需要更少的任务试次来习得哈萨克语语音。关于组间差异，在最初接触哈萨克语时，多语言者的反应时减少幅度明显大于双语者。对于多语言者来说，在随后的新语法条件下，双侧额颞区的激活保持在比初始水平更高的水平。对于双语者来说，基底神经节/丘脑和小脑的激活每次都降低到初始水平。直接的组间比较显示，多语言者左侧腹下额前回的激活明显增强。这些结果表明，多语言者的语法相关和领域一般性大脑网络都得到了增强。我们还意外地观察到多语言者在视觉区域的显著激活，这意味着即使在单独听语音时，他们也会使用视觉表现。因为多语言者能够成功地以累积的方式利用所获得的知识，所以结果支持语言习得的累积增强模型。
