Knowledge of stimulus repetition affects the magnitude and spatial distribution of low-frequency event-related brain potentials
Knowledge of stimulus repetition affects the magnitude and spatial distribution of low-frequency event-related brain potentials
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DOI：
10.1159/000064444
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发表时间：
2002-09-01
影响因子：
1.6
通讯作者：
Dzau, JR
中科院分区：
文献类型：
--
作者：
Clementz, BA;Barber, SK;Dzau, JR
速率效应被定义为随着刺激频率的增加而引起的脑反应幅度的减少。在听觉配对刺激范式中，第二个刺激在50 ms的潜伏期诱发了一个较小振幅的反应，这反映了注意前感觉门控机制。本研究调查了期望和/或注意偏差可能改变与速率效应相关的诱发电位的可能性。记录30个通道的脑电数据，受试者接受240次1、2、3次点击刺激（连续刺激间隔500 ms）。一半的受试者知道（封闭条件），一半的受试者不知道（混合条件）在给定的试验中他们会收到多少刺激。封闭条件下受试者的速率效应明显大于混合条件下受试者的速率效应。这种效应只出现在事件相关脑电位（ERP，低于10 Hz）的低频部分，并在刺激呈现（P-1-N-1-P-2复合体）后30 - 60、90 - 160和190 - 260 ms发生。混合条件下的被试也有更大的颞叶通道对erp的贡献。这些结果表明，速度效应可以被预期显著改变，这与配对刺激模式下50 ms附近的erp仅反映注意前感觉门控机制的理论不一致。版权所有(C) 2002 S. Karger AG，巴塞尔。
Rate effects are defined as a reduction in amplitude of an evoked brain response with increasing stimulus frequency. In auditory paired-stimulus paradigms, a smaller amplitude evoked response to the second stimulus at a latency of 50 ms has been proposed to index a preattentive sensory gating mechanism. The present study investigated the possibility that expectancy and/or attentional biases could alter evoked potentials associated with rate effects. EEG data were recorded from 30 channels while subjects received 240 trials of 1, 2 or 3 click stimuli (with successive stimuli being separated by 500-ms intervals). Half of the subjects knew (blocked condition) and half of the subjects did not know (mixed condition) how many stimuli they would receive on a given trial. Subjects in the blocked condition had a significantly larger rate effect than subjects in the mixed condition. This effect was present only for low-frequency components of the event-related brain potential (ERP; below 10 Hz) and occurred from 30 to 60, 90 to 160 and 190 to 260 ms after stimulus presentation (P-1-N-1-P-2 complex). Mixed condition subjects also had larger contributions to their ERPs from temporal channels. These results suggest that the rate effect can be significantly altered by expectancy, and they are inconsistent with the thesis that ERPs near 50 ms in a paired-stimulus paradigm solely index a preattentive sensory gating mechanism. Copyright (C) 2002 S. Karger AG, Basel.