Max Planck Institute for Human Cognitive and Brain Sciences, Brain Networks Group, Leipzig, Germany.
Beijing Normal University, College of Chinese Language and Culture, Beijing.
Hum Brain Mapp. 2021 Aug 15;42(12):3858-3870. doi: 10.1002/hbm.25470. Epub 2021 May 4.
The adult human brain remains plastic even after puberty. However, whether first language (L1) training in adults can alter the language network is yet largely unknown. Thus, we conducted a longitudinal training experiment on syntactically complex German sentence comprehension. Sentence complexity was varied by the depth of the center embedded relative clauses (i.e., single or double embedded). Comprehension was tested after each sentence with a question on the thematic role assignment. Thirty adult, native German speakers were recruited for 4 days of training. Magnetoencephalography (MEG) data were recorded and subjected to spectral power analysis covering the classical frequency bands (i.e., theta, alpha, beta, low gamma, and gamma). Normalized spectral power, time-locked to the final closure of the relative clause, was subjected to a two-factor analysis ("sentence complexity" and "training days"). Results showed that for the more complex sentences, the interaction of sentence complexity and training days was observed in Brodmann area 44 (BA 44) as a decrease of gamma power with training. Moreover, in the gamma band (55-95 Hz) functional connectivity between BA 44 and other brain regions such as the inferior frontal sulcus and the inferior parietal cortex were correlated with behavioral performance increase due to training. These results show that even for native speakers, complex L1 sentence training improves language performance and alters neural activities of the left hemispheric language network. Training strengthens the use of the dorsal processing stream with working-memory-related brain regions for syntactically complex sentences, thereby demonstrating the brain's functional plasticity for L1 training.
成人的大脑在青春期后仍然具有可塑性。然而，成人的第一语言（L1）训练是否可以改变语言网络在很大程度上尚不清楚。因此，我们进行了一项关于复杂德语句子理解的纵向训练实验。句子的复杂性通过中心嵌套关系从句的深度来改变（即，单层嵌套或双层嵌套）。在每个句子之后，用一个关于主题角色分配的问题进行理解测试。30 名成年母语为德语的人被招募参加为期 4 天的训练。记录了脑磁图（MEG）数据，并进行了频谱功率分析，涵盖了经典频段（即 theta、alpha、beta、低 gamma 和 gamma）。归一化的频谱功率，与关系从句的最后闭合时间锁相，进行了双因素分析（“句子复杂性”和“训练天数”）。结果表明，对于更复杂的句子，在布罗卡区 44（BA 44）观察到句子复杂性和训练天数的交互作用，表现为随着训练的进行，伽马功率下降。此外，在伽马频段（55-95 Hz），BA 44 与其他大脑区域（如额下回和顶下小叶）之间的功能连接与由于训练而导致的行为表现的增加相关。这些结果表明，即使对于母语为英语的人来说，复杂的 L1 句子训练也可以提高语言表现并改变左半球语言网络的神经活动。训练加强了与工作记忆相关的大脑区域的背侧处理流在句法复杂句子中的使用，从而证明了大脑对 L1 训练的功能可塑性。
