Institute of Cognitive Neuroscience, University College London, UK.
Institute of Cognitive Neuroscience, University College London, UK.
Neuroimage. 2013 Nov 1;81:158-163. doi: 10.1016/j.neuroimage.2013.04.094. Epub 2013 May 3.
The brain is frequently confronted with sensory information that elicits conflicting response choices. While much research has addressed the top down control mechanisms associated with detection and resolution of response competition, the effects of response competition on sensory processing in the primary visual cortex remain unclear. To address this question we modified a typical 'flanker task' (Eriksen and Eriksen, 1974) so that the effects of response competition on human early retinotopic visual cortex could be assessed. Healthy human participants were scanned using fMRI while making a speeded choice response that classified a target object image into one of two categories (e.g. fruits, animals). An irrelevant distractor image that was either congruent (same image as target), incongruent (image from opposite category as target), or neutral (image from task-irrelevant category, e.g. household items) was also present on each trial, but in a different quadrant of the visual field relative to the target. Retinotopic V1 areas responding to the target stimuli showed increased response to targets in the presence of response-incongruent (compared to response-neutral) distractors. A negative correlation with behavioral response competition effects indicated that an increased primary visual cortical response to targets in the incongruent (vs. neutral) trials is associated with a reduced response competition effect on behavior. These results suggest a novel conflict resolution mechanism in the primary visual cortex.
大脑经常会面对引发冲突反应选择的感觉信息。虽然很多研究都探讨了与检测和解决反应竞争相关的自上而下的控制机制，但反应竞争对视皮层初级视觉处理的影响仍不清楚。为了解决这个问题，我们修改了典型的“侧抑制任务”（Eriksen 和 Eriksen，1974），以便评估反应竞争对人类早期视知觉皮层的影响。健康的人类参与者在进行快速选择反应任务时接受 fMRI 扫描，该任务将目标对象图像分类为两个类别之一（例如，水果、动物）。在每个试验中，还有一个无关的干扰图像，它要么与目标一致（与目标相同的图像），要么与目标不一致（与目标相反类别的图像），要么是中性（来自与任务无关的类别，例如，家庭用品），但相对于目标，它出现在视野的不同象限。对目标刺激做出反应的视皮层 V1 区域在存在反应不一致（与反应中性相比）干扰物的情况下，对目标的反应增加。与行为反应竞争效应的负相关表明，在不一致（与中性相比）试验中，对目标的初级视觉皮层反应增加与行为上的反应竞争效应降低有关。这些结果表明，初级视觉皮层中存在一种新的冲突解决机制。
