Parietal cortex mediates perceptual Gestalt grouping independent of stimulus size
Parietal cortex mediates perceptual Gestalt grouping independent of stimulus size
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DOI：
10.1016/j.neuroimage.2016.03.008
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发表时间：
2016-06-01
期刊：
影响因子：
5.7
通讯作者：
Bartels, Andreas
中科院分区：
文献类型：
--
作者：
Grassi, Pablo R.;Zaretskaya, Natalia;Bartels, Andreas
将局部运动元素整合到统一的完形知觉中，以前曾被认为与顶叶后皮质有关。对于枕部其他区域缺乏受累，有两种可能的解释。首先，顶叶皮质在进行分组的功能上确实是独一无二的。另一种可能性是，其他视觉区域也可以进行分组，但先前使用的局部元素的大空间分隔超过了神经元的感受野(RF)大小，从而阻止了它们的参与。在这项研究中，我们区分了这两种选择。我们使用功能磁共振成像测量了全脑活动，以响应双稳态运动错觉，这种错觉诱导了对虚幻的全局格式塔或局部元素的相互排斥的感知。刺激有两种大小，一种是已知仅激活IPS的大版本，另一种是足够小的版本，足以适应V5/MT等中层背侧区域的RFS。我们发现，除了顶叶皮质之外，没有一个单独的局部运动区表现出对整体格式塔知觉的偏好，即使是较小版本的刺激。这一结果表明，运动分组是由一种特殊的大小不变机制介导的，顶叶皮质是其解剖基础。(C)2016 Elsevier Inc.保留所有权利。
The integration of local moving elements into a unified gestalt percept has previously been linked to the posterior parietal cortex. There are two possible interpretations for the lack of involvement of other occipital regions. The first is that parietal cortex is indeed uniquely functionally specialized to perform grouping. Another possibility is that other visual regions can perform grouping as well, but that the large spatial separation of the local elements used previously exceeded their neurons' receptive field (RF) sizes, preventing their involvement. In this study we distinguished between these two alternatives. We measured whole-brain activity using fMRI in response to a bistable motion illusion that induced mutually exclusive percepts of either an illusory global Gestalt or of local elements. The stimulus was presented in two sizes, a large version known to activate IPS only, and a version sufficiently small to fit into the RFs of mid-level dorsal regions such as V5/MT. We found that none of the separately localized motion regions apart from parietal cortex showed a preference for global Gestalt perception, even for the smaller version of the stimulus. This outcome suggests that grouping-by-motion is mediated by a specialized size-invariant mechanism with parietal cortex as its anatomical substrate. (C) 2016 Elsevier Inc. All rights reserved.