早期ERP效应与视觉注意空间等级的脑调节机制

通过事件相关电位(ERP)记录研究注意的空间等级的脑内时程动态变化。视觉搜索任务的目标受不同大小提示范围的启动。提示范围增大时,识别目标的反应时延长,P1波幅增大而N1波幅减小,该效应在短间隔条件下尤为明显。P1增大反映了促进目标识别时,适当注意范围的空间等级变化需要额外的运算资源。而N1波幅减小则可能扩散了空间注意倾斜。研究结果提供了以下电生理学证据：注意空间等级的改变调节了早期视皮层的神经活动,并激活了视觉搜索中至少2个时间重叠的ERP成分。

THE EARLY ERP EFFECTS REFLECT NEURAL ACTIVITY IN SPATIAL SCALE OF VISUAL ATTENTION

To investigate temporal dynamics of the spatial scaling of attention during visual search, event-related potentials (ERPs) were measured in young subjects who performed a search task in which the search array was preceded by valid cues that varied in size and hence in precision of target localization. The effects of cue size on P1 and N1 components, and the time course of these effects with variation in cue-target stimulus onset asynchrony (SOA), were examined. Reaction time (RT) to discriminate a target was prolonged as cue size increased. The amplitudes of the posterior P1 and N1 evoked by the search array were affected in opposite ways by the size of the precue: P1 amplitude increased whereas N1 amplitude decreased as cue size increased, particularly following the shortest SOA. The results showed that when top-down information about the region to be searched was less precise (larger cues), RT slowed and the neural generators of P1 became more active, reflecting the additional computations required in changing the spatial scale of attention to the appropriate element size to facilitate target discrimination. In contrast, the decrease in N1 amplitude with cue size may reflect the broadening of the spatial gradient of attention. The results provided electrophysiological evidence that changes in the spatial scale of attention modulate neural activity in early visual cortical areas and activate at least two temporally-overlapping component processes during visual search.