TOPOGRAPHY OF THE N400 - BRAIN ELECTRICAL-ACTIVITY REFLECTING SEMANTIC EXPECTANCY
TOPOGRAPHY OF THE N400 - BRAIN ELECTRICAL-ACTIVITY REFLECTING SEMANTIC EXPECTANCY
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DOI：
10.1016/0168-5597(93)90004-9
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发表时间：
1993-05-01
期刊：
影响因子：
--
通讯作者：
POSNER, MI
中科院分区：
文献类型：
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作者：
CURRAN, T;TUCKER, DM;POSNER, MI
当受试者阅读语义上意想不到的单词时，与阅读预期单词时的反应相比，脑电活动在大约400毫秒的时间内显示出负偏转。为了研究与这种效应相关的大脑系统，我们使用了一个密集的（64通道）电极阵列和两个独立于参考的测量方法，一个估计平均电位梯度，另一个估计径向电流密度。通过这些测量，事件相关脑电位（ERP）开始于大约70毫秒的P1，反映了枕顶区域的双侧电流源。接着是强烈左偏化的Nl，在180毫秒左右达到峰值，并伴有前路P2阳性。然后出现一个单独的后阳性模式，似乎重复了P1的地形。接下来，在大约350毫秒时，对应于谐音词的ERP发展为P300或LPC，其特征是头部上表面出现弥漫性正信号，下表面出现若干负信号。LPC的上源/下汇模式在左半球更为明显。相反，在这个区间中，不协调词的ERP将N400显示为不存在地形特征的时间段。在大约400毫秒时，不协调单词的ERP开始形成LPC，然后在两个半球上保持相对对称。
When subjects read an semantically unexpected word, the brain electrical activity shows a negative deflection at about 400 msec in comparison with the response to an expected word. In order to study the brain systems related to this effect we mapped it with a dense (64-channel) electrode array and two reference-independent measures, one estimating the average potential gradients and the other radial current density. With these measures, the event-related brain potential (ERP) begins at about 70 msec with the P1, reflecting bilateral current sources over occipitoparietal areas. A strongly left-lateralized Nl then follows, peaking at about 180 msec, accompanied by an anterior positivity, the P2. A separate posterior positive pattern then emerges that seems to repeat the topography of the P1. Next, at about 350 msec, the ERP for the congruous word develops a P300 or LPC, characterized by a diffuse positivity over the superior surface of the head and several negativities over inferior regions. This superior source/inferior sink pattern of the LPC is greater over the left hemisphere. In contrast, the ERP for the incongruous word in this interval displays the N400 as a period in which topographic features are absent. At about 400 msec the ERP for the incongruous word begins to develop an LPC, which then remains relatively symmetric over the two hemispheres.