Wu Junjie, Cheng Yao, Qu Xingfang, Kang Tianmin, Cai Yimin, Wang Peng, Zaccarella Emiliano, Friederici Angela D, Hartwigsen Gesa, Chen Luyao
Key Research Base of Humanities and Social Sciences of the Ministry of Education, Academy of Psychology and Behavior, Tianjin Normal University, Tianjin, China.
Max Planck Partner Group, School of International Chinese Language Education, Beijing Normal University, Beijing, China.
Neurobiol Lang (Camb). 2024 Jun 24;5(2):608-627. doi: 10.1162/nol_a_00140. eCollection 2024.
The structure of human language is inherently hierarchical. The left posterior inferior frontal gyrus (LpIFG) is proposed to be a core region for constructing syntactic hierarchies. However, it remains unclear whether LpIFG plays a causal role in syntactic processing in Mandarin Chinese and whether its contribution depends on syntactic complexity, working memory, or both. We addressed these questions by applying inhibitory continuous theta-burst stimulation (cTBS) over LpIFG. Thirty-two participants processed sentences containing embedded relative clauses (i.e., complex syntactic processing), syntactically simpler coordinated sentences (i.e., simple syntactic processing), and non-hierarchical word lists (i.e., word list processing) after receiving real or sham cTBS. We found that cTBS significantly increased the coefficient of variation, a representative index of processing stability, in complex syntactic processing (esp., when subject relative clause was embedded) but not in the other two conditions. No significant changes in ' and reaction time were detected in these conditions. The findings suggest that (a) inhibitory effect of cTBS on the LpIFG might be prominent in perturbing the complex syntactic processing stability but subtle in altering the processing quality; and (b) the causal role of the LpIFG seems to be specific for syntactic processing rather than working memory capacity, further evidencing their separability in LpIFG. Collectively, these results support the notion of the LpIFG as a core region for complex syntactic processing across languages.
人类语言的结构本质上是分层级的。左后下额回（LpIFG）被认为是构建句法层级的核心区域。然而，LpIFG在汉语句法处理中是否起因果作用，以及它的作用是否取决于句法复杂性、工作记忆或两者，仍不清楚。我们通过在LpIFG上应用抑制性连续theta爆发刺激（cTBS）来解决这些问题。32名参与者在接受真实或伪cTBS后，对包含嵌入式关系从句的句子（即复杂句法处理）、句法上更简单的并列句（即简单句法处理）和非层级单词列表（即单词列表处理）进行加工。我们发现，cTBS显著增加了复杂句法处理（特别是当主语关系从句被嵌入时）中变异系数（一个处理稳定性的代表性指标），但在其他两种情况下没有增加。在这些情况下，未检测到‘和反应时间的显著变化。研究结果表明：（a）cTBS对LpIFG的抑制作用在干扰复杂句法处理稳定性方面可能很突出，但在改变处理质量方面很微妙；（b）LpIFG的因果作用似乎特定于句法处理而非工作记忆容量，进一步证明了它们在LpIFG中的可分离性。总的来说，这些结果支持了LpIFG作为跨语言复杂句法处理核心区域的观点。
