Key Research Base of Humanities and Social Sciences of the Ministry of Education, Academy of Psychology and Behavior, Tianjin Normal University, Tianjin, China.
Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, Australia.
Cereb Cortex. 2024 Nov 5;34(11). doi: 10.1093/cercor/bhae452.
Language production in bilinguals relies on the collaborative interaction between two neural systems: the language control system (e.g. the right inferior frontal gyrus) and the language processing system (e.g. the left superior temporal gyrus). However, the causal mapping between these brain systems and their cognitive functions, as well as the temporal dynamics between these two systems during bilingual language production, remain unclear. To investigate this, our study applied online transcranial magnetic stimulation to the right inferior frontal gyrus and left superior temporal gyrus in Chinese-English bilinguals performing a language-switching task. Transcranial magnetic stimulation was administered within seven 100 ms time windows (TW1 to TW7) following the picture onset. We observed time window-specific enhancements of language control, as shown by a significant reduction in switching costs upon the stimulations on both sites relative to the sham stimulation: specifically, the right inferior frontal gyrus at TW1, TW2, TW4, and TW5 and the left superior temporal gyrus at TW2 and TW5. These findings indicate a double-strike top-down control mechanism underpinned by the pathway from the right inferior frontal gyrus to the right inferior frontal gyrus, potentially during both stages during production: the language task schema and the lemma selection. Our study provides the first evidence of the dynamic interactions between language control and processing systems causally underpinning bilingual language production.
语言控制系统（例如右侧额下回）和语言处理系统（例如左侧颞上回）。然而，这些大脑系统及其认知功能之间的因果关系以及在双语语言产生过程中这两个系统之间的时间动态仍然不清楚。为了研究这一点，我们的研究在执行语言转换任务的汉英双语者中应用了在线经颅磁刺激技术，对右侧额下回和左侧颞上回进行刺激。经颅磁刺激在图片出现后的七个 100ms 时间窗（TW1 到 TW7）内进行。我们观察到语言控制的时间窗特异性增强，这表现为与假刺激相比，在两个部位的刺激下，转换成本显著降低：具体来说，右侧额下回在 TW1、TW2、TW4 和 TW5，左侧颞上回在 TW2 和 TW5。这些发现表明，由右侧额下回到右侧额下回的通路支持一种双重自上而下的控制机制，这可能发生在产生过程的两个阶段：语言任务图式和词干选择。我们的研究首次提供了证据，证明了双语语言产生的语言控制和处理系统之间的动态相互作用。
