Early neural activation for lexico-semantic access in the left anterior temporal area analyzed by an fMRI-assisted MEG multidipole method
Early neural activation for lexico-semantic access in the left anterior temporal area analyzed by an fMRI-assisted MEG multidipole method
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DOI：
10.1016/j.neuroimage.2008.10.021
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发表时间：
2009-02-01
期刊：
影响因子：
5.7
通讯作者：
Murata, Tsutomu
中科院分区：
文献类型：
--
作者：
Fujimaki, Norio;Hayakawa, Tomoe;Murata, Tsutomu
为了确定词汇语义获取的时间和位置，我们通过脑磁图（MEG）和功能磁共振成像（fMRI）测量神经激活，并通过fMRI辅助的MEG多偶极子分析估计神经源。由于语音处理和词汇语义获取的激活在许多大脑区域重叠，我们比较了词汇和语音决策任务的激活。前一项任务需要视觉形式加工、语音加工和词汇语义获取，后一项任务只需要视觉形式和语音加工，两个任务的语音任务要求相似。10个被试中有9个或10个被试被激活的区域分别是颞上、下顶叶区、颞前区、双脑额下区和左腹侧枕颞区。在视觉刺激出现后200 ~ 400 ms的所有50 ms时间窗内，两种任务的左前颞区激活均存在显著差异。以往对语义痴呆的研究和对正常受试者的神经影像学研究表明，该区域在获取语义知识方面起着关键作用。在100 ~ 150 ms和400 ~ 450 ms的时间窗内，各区域的任务差异呈现出共性，说明视觉形式加工的早期差异和决策过程的后期差异。结果表明，左前颞区词汇语义通路的激活始于早期视觉形态加工后200 ~ 250 ms的时间窗口。(C) 2008爱思唯尔公司版权所有。
To determine the time and location of lexico-semantic access, we measured neural activations by magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) and estimated the neural sources by fMRI-assisted MEG multidipole analysis. Since the activations for phonological processing and lexico-semantic access were reported to overlap in many brain areas, we compared the activations in lexical and phonological decision tasks. The former task required visual form processing, phonological processing, and lexico-semantic access, while the latter task required only visual form and phonological processing, with similar phonological task demands for both tasks. The activation areas observed among 9 or 10 subjects out of 10 were the superior temporal and inferior parietal areas, anterior temporal area, and inferior frontal area of both hemispheres, and the left ventral occipitotemporal area. The activations showed a significant difference between the 2 tasks in the left anterior temporal area in all 50-ms time windows between 200-400 ms from the onset of visual stimulus presentation. Previous studies on semantic dementia and neuroimaging studies on normal subjects have shown that this area plays a key role in accessing semantic knowledge. The difference between the tasks appeared in common to all areas in the time windows of 100-150 ms and 400-450 ms, suggesting early differences in visual form processing and late differences in the decision process, respectively. The present results demonstrate that the activations for lexico-semantic access in the left anterior temporal area start in the time window of 200-250 ms, after early visual form processing. (C) 2008 Elsevier Inc. All rights reserved.