Human visual and parietal cortex encode visual choices independent of motor plans
Human visual and parietal cortex encode visual choices independent of motor plans
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DOI：
10.1016/j.neuroimage.2012.08.027
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发表时间：
2012-11-15
期刊：
影响因子：
5.7
通讯作者：
Haynes, John-Dylan
中科院分区：
文献类型：
--
作者：
Hebart, Martin N.;Donner, Tobias H.;Haynes, John-Dylan
感知决策需要将分级的感觉信号转化为分类的判断。通常，这些判断和特定的运动反应之间存在直接映射。然而，当刺激-反应映射固定时，决策背后的神经活动不能与反映运动规划的神经活动分开。几项人类神经影像学研究报告了与感知决策相关的大脑活动变化。然而，迄今为止，当运动规划与决策过程脱钩时，具体的选择在哪里以及如何编码在人脑中仍然是未知的。为了解决这个问题，我们让受试者在不同运动强度下判断动态随机点图案的运动方向，同时用fMRI测量他们的大脑活动。我们使用多变量解码分析来搜索整个大脑，以寻找编码受试者选择的大脑活动模式。为了将决策过程与运动规划分离，受试者仅在刺激呈现后才被告知所需的运动反应。早期视觉和下顶叶皮层的fMRI信号模式预测了受试者的知觉选择，而与运动规划无关。在多个运动强度水平上，甚至在没有任何连贯刺激运动的情况下，情况都是如此。我们还发现，选择性脑信号的皮层分布依赖于刺激强度：虽然视觉皮层进行了大部分的选择性信息的强烈运动，顶叶皮层的信息减少与运动的连贯性。这些结果表明，人类的视觉和下顶叶皮层进行信息的视觉决策在一个更抽象的格式比可以解释的简单的运动意图。这两个大脑区域在面对强和弱的感官证据时，可能会不同地参与感知决策。(C)2012 Elsevier Inc. All rights reserved.
Perceptual decision-making entails the transformation of graded sensory signals into categorical judgments. Often, there is a direct mapping between these judgments and specific motor responses. However, when stimulus-response mappings are fixed, neural activity underlying decision-making cannot be separated from neural activity reflecting motor planning. Several human neuroimaging studies have reported changes in brain activity associated with perceptual decisions. Nevertheless, to date it has remained unknown where and how specific choices are encoded in the human brain when motor planning is decoupled from the decision process. We addressed this question by having subjects judge the direction of motion of dynamic random dot patterns at various levels of motion strength while measuring their brain activity with fMRI. We used multivariate decoding analyses to search the whole brain for patterns of brain activity encoding subjects' choices. To decouple the decision process from motor planning, subjects were informed about the required motor response only after stimulus presentation. Patterns of fMRI signals in early visual and inferior parietal cortex predicted subjects' perceptual choices irrespective of motor planning. This was true across several levels of motion strength and even in the absence of any coherent stimulus motion. We also found that the cortical distribution of choice-selective brain signals depended on stimulus strength: While visual cortex carried most choice-selective information for strong motion, information in parietal cortex decreased with increasing motion coherence. These results demonstrate that human visual and inferior parietal cortex carry information about the visual decision in a more abstract format than can be explained by simple motor intentions. Both brain regions may be differentially involved in perceptual decision-making in the face of strong and weak sensory evidence. (C) 2012 Elsevier Inc. All rights reserved.