Electrophysiological Indices of Target and Distractor Processing in Visual Search
Electrophysiological Indices of Target and Distractor Processing in Visual Search
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DOI：
10.1162/jocn.2009.21039
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发表时间：
2009-04-01
影响因子：
3.2
通讯作者：
McDonald, John J.
中科院分区：
文献类型：
--
作者：
Hickey, Clayton;Di Lollo, Vincent;McDonald, John J.
在干扰物中对目标的注意选择可以用被称为N2 pc的事件相关电位（ERP）成分来索引。N2 pc的理论解释表明，它反映了注意力的基本机制，通过抑制来自干扰物的神经活动来保护目标的皮层表征。然而，来自人类电生理学以外的领域的结果表明，注意力并不仅仅通过干扰抑制来发挥作用;相反，它调节了目标和干扰物的处理。我们进行了四个ERP实验，旨在探讨是否N2 PC反映了多种注意机制。我们的目标是调和表面上相互矛盾的结果，在注意力的电生理学研究与使用其他方法获得的。参与者观看包含一个目标和一个干扰物的视觉搜索阵列。在实验1至3中，分心物是等亮度的背景，因此，没有引起早期偏侧ERP活动。这项工作揭示了一种新的对侧ERP组件，似乎反映了直接抑制的皮质表示的干扰。因此，我们将这一成分命名为分心物积极性（PD）。在实验4中，与目标处理相关的ERP组件被另外分离。我们将该分量称为目标负性（NT）。我们认为，N2 pc反映了PD和NT的总和，这些离散的组件可能已经混淆在早期的电生理研究。总的来说，这项研究表明，注意力作用于目标和分心表征，这可以在视觉ERP中索引。
Attentional selection of a target presented among distractors can be indexed with an event-related potential (ERP) component known as the N2pc. Theoretical interpretation of the N2pc has suggested that it reflects a fundamental mechanism of attention that shelters the cortical representation of targets by suppressing neural activity stemming from distractors. Results from fields other than human electrophysiology, however, suggest that attention does not act solely through distractor suppression; rather, it modulates the processing of both target and distractors. We conducted four ERP experiments designed to investigate whether the N2pc reflects multiple attentional mechanisms. Our goal was to reconcile ostensibly conflicting outcomes obtained in electrophysiological studies of attention with those obtained using other methodologies. Participants viewed visual search arrays containing one target and one distractor. In Experiments 1 through 3, the distractor was isoluminant with the background, and therefore, did not elicit early lateralized ERP activity. This work revealed a novel contralateral ERP component that appears to reflect direct suppression of the cortical representation of the distractor. We accordingly name this component the distractor positivity (PD). In Experiment 4, an ERP component associated with target processing was additionally isolated. We refer to this component as the target negativity (NT). We believe that the N2pc reflects the summation of the PD and NT, and that these discrete components may have been confounded in earlier electrophysiological studies. Overall, this study demonstrates that attention acts on both target and distractor representations, and that this can be indexed in the visual ERP.