Williams Joshua T, Darcy Isabelle, Newman Sharlene D
Department of Psychological and Brain Sciences, Indiana University, United States; Program in Cognitive Science, Indiana University, United States; Speech and Hearing Sciences, Indiana University, United States.
Program in Cognitive Science, Indiana University, United States; Second Language Studies, Indiana University, United States.
Cortex. 2016 Feb;75:56-67. doi: 10.1016/j.cortex.2015.11.015. Epub 2015 Dec 1.
The present study tracked activation pattern differences in response to sign language processing by late hearing second language learners of American Sign Language. Learners were scanned before the start of their language courses. They were scanned again after their first semester of instruction and their second, for a total of 10 months of instruction. The study aimed to characterize modality-specific to modality-general processing throughout the acquisition of sign language. Results indicated that before the acquisition of sign language, neural substrates related to modality-specific processing were present. After approximately 45 h of instruction, the learners transitioned into processing signs on a phonological basis (e.g., supramarginal gyrus, putamen). After one more semester of input, learners transitioned once more to a lexico-semantic processing stage (e.g., left inferior frontal gyrus) at which language control mechanisms (e.g., left caudate, cingulate gyrus) were activated. During these transitional steps right hemispheric recruitment was observed, with increasing left-lateralization, which is similar to other native signers and L2 learners of spoken language; however, specialization for sign language processing with activation in the inferior parietal lobule (i.e., angular gyrus), even for late learners, was observed. As such, the present study is the first to track L2 acquisition of sign language learners in order to characterize modality-independent and modality-specific mechanisms for bilingual language processing.
本研究追踪了美国手语的晚期听力第二语言学习者在处理手语时的激活模式差异。学习者在语言课程开始前接受扫描。在第一学期和第二学期的教学结束后，他们再次接受扫描，总共接受了10个月的教学。该研究旨在描述在整个手语习得过程中从特定模态处理到一般模态处理的特征。结果表明，在手语习得之前，与特定模态处理相关的神经基质就已存在。经过大约45小时的教学后，学习者开始基于语音处理手语（例如，缘上回、壳核）。再经过一个学期的输入后，学习者再次过渡到词汇语义处理阶段（例如，左额下回），此时语言控制机制（例如，左尾状核、扣带回）被激活。在这些过渡阶段，观察到右半球的参与，且左侧化程度增加，这与其他本土手语使用者和口语第二语言学习者相似；然而，即使是晚期学习者，也观察到在顶下小叶（即角回）激活的情况下对手语处理的专门化。因此，本研究首次追踪手语学习者的第二语言习得，以描述双语语言处理中与模态无关和与模态相关的机制。
