生体医工学
Online ISSN : 1881-4379
Print ISSN : 1347-443X
ISSN-L : 1347-443X
研究
日本語複文読解時における統語処理のMEG計測
渡邊 直輝竹内 文也栗城 眞也萩原 裕子
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2005 年 43 巻 4 号 p. 631-637

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Reading comprehension requires the processing of both semantic components and grammatical aspects, which includes the analysis of words and their order (syntax) to understand the sentence structure. Here, we report an MEG (magnetoencephalography) study performed to measure the time course of neural responses and to image their activities while subjects were reading Japanese complex sentences. The stimulus sentences consisted of subject, object, and verb phrases, constituting the main clause and subordinate clause, and were presented visually phrase-by-phrase while conducting the MEG. We examined normal word-order (CAN ; canonical) sentences and scrambled (SCR) sentences that included “displacement” of the object phrase to the top of its subordinate clause. The localization of distributed sources was performed for the response to the object (or subject in the SCR sentence) phrase and verb phrase in the subordinate clause. Main activities in the left hemisphere were commonly found for the two phrases in the occipitotemporal border (fusiform gyrus) and occipital (visual cortex) regions within 190-300 ms from the onset of the phrases. After 300 ms, activities became strong in the prefrontal region. These activities in the posterior and anterior brain regions may reflect visual form analysis of words and working memory process, respectively. For the displaced subject phrase of the SCR sentence, early activity at about 140 ms was found in the left occipital-to-occipitotemporal region, suggesting facilitation of visual form analysis. Specific activity was also found strongly in the region around the left motor/premotor cortex in a wide latency range of 200-550 ms for both subject and verb phrases of SCR sentence. This finding suggests the possibility of motor/premotor activity, such as a mirror neuron circuit, in processing the displaced phrase without overt speech. Thus, the present study indicates the involvement of multiple regions other than classical language areas when processing syntactic aspects of scrambled sentences.

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© 2005 社団法人日本生体医工学会
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