单词产生任务中汉字认知加工的神经机制

Neural Mechanisms Underlying the Processing of Chinese Characters in a Word Generation Task

采用事件相关电位(ERP)技术探讨了汉字字形的单词产生过程中的脑内时程动态变化。结果发现,无论是"推测成功"(增加一笔可构成另一个汉字)还是"判断成功"(增加一笔无法构成另一个汉字)情况下,刺激都诱发了N120和P220成分,其中N120可能反映了汉字笔画部件知觉特征的早期加工,而P220可能与笔画部件的特征整合以及对汉字的最初识别和编码有关。随后,两类反应都诱发了明显的P500,可能属于晚期P300成分,在一定程度上反映了工作记忆中新词产生的假设-检验过程。在700-1000ms内,"推测成功"比"判断成功"诱发了一个更大的ERP负成分(N700-1000),偶极子溯源分析的结果显示,该负成分主要起源于扣带后回附近,可能与新词的成功获得以及正确检验有关。

The present study was to investigate spatiotemporal cortical activation patterns in the processing of Chinese characters during a word generation task. Event-related brain potentials （ERPs） were measured when the subjects generated a new character by adding a stroke to Chinese word. The results showed that Chinese characters elicited some early ERP components under two different conditions, N120 and P220, According to previous studies, N120 might be related to the initial visual perception of strokes, while P220 reflected early orthographic distinction and evaluation. Subsequently, generation success and judgment success both elicited a late positive component （P500）, related to hypothesis-testing processing during word generation in working memory. Then, generation success elicited a more negative ERP deflection （N700-1000） than did judgment succeeds between 700-1000 ms. Dipole analysis localized the generator of NT00-1000 the in posterior cingulate cortex, possibly related to successful word reconstruction and recollective process in the long-term memory.