Presentation
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The functional separation and compensation between the left anterior and the posterior MFG in Chinese character reading
Poster B9 in Poster Session B and Reception, Thursday, October 6, 6:30 - 8:30 pm EDT, Millennium Hall
Fakun Chen1, Tian Chen1, Wenqi Cai1, Xiaojuan Wang1, Jianfeng Yang1; 1Shaanxi Normal University
The left middle frontal gyrus (MFG) is a region identified in Chinese character reading, which is considered specific to Chinese and responsible for verbal working memory. However, whether the function of the left MFG in Chinese reading is language-specific (verbal) or domain-general (nonverbal) working memory is unclear. The current study addressed this issue by combining the neural correlations (functional near-infrared spectroscopy, fNIRS) and neural causal (transcranial magnetic stimulation, TMS) technologies. Experiment 1 examined the function of left MFG in reading Chinese characters using fNIRS technology. We conducted a factorial design by manipulating the working memory (WM) load (0-back vs 2-back task) for two types of scripts (Chinese characters vs Yi scripts). The anterior MFG (BA46/9) showed a significant main effect of WM, in which it engaged more for 2-back than for 0-back task. In contrast, the posterior MFG (dorsal BA6) showed a significant interaction between script type and WM because it involved working memory only for Chinese characters but not Yi scripts. These results indicate that the left MFG engaged in Chinese character reading due to the working memory. Moreover, the anterior and the posterior part of the left MFG had a distinct function. The anterior MFG was domain-general (both for verbal and nonverbal), and the posterior MFG was language-specific (only for verbal) working memory. To further confirm the above results, Experiment 2 established the neural causality between the activities of the sub-regions of MFG and the language-specific and domain-general working memory. The experiment design was the same as experiment 1. Only the fNIRS data were collected after each participant received an offline continuous theta-burst transcranial magnetic stimulation (cTBS) to virtual damage to the anterior (BA46/9) and the posterior (BA6) MFG observed in experiment 1. When the anterior MFG was damaged, this region showed a significant interaction that the WM effect was observed for nonverbal Yi scripts but not for Chinese characters. Meanwhile, the posterior MFG showed a significant interaction that the WM effect was observed only for nonverbal Yi scripts but not for Chinese characters. It suggested that the virtual damage to the anterior MFG reduced its sensitivity to the language-specific WM but maintained its function of domain-general WM. Furthermore, the reduced function of anterior MFG also reduced the sensitivity of language-specific WM and increased the load of domain-general WM at the posterior MFG. When the posterior MFG was damaged, this region showed a reverse interaction that the WM effect was only significant for nonverbal Yi script but not for Chinese characters. Meanwhile, the anterior MFG remained the main effect of WM. It suggested that the damage to the posterior MFG reduced its sensitivity to the language-specific WM but remained the anterior MFG intact. In sum, the left MFG engaged in the working memory for reading Chinese characters. Its anterior region may be related to the domain-general WM, and the posterior part may be associated with the language-specific verbal WM. The anterior and the posterior sub-region showed the functional separation and compensation in Chinese character reading.
Topic Areas: Reading, Control, Selection, and Executive Processes