Analysis of the context integration mechanisms underlying figure-ground organization in the visual cortex.
Analysis of the context integration mechanisms underlying figure-ground organization in the visual cortex.
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DOI：
10.1523/jneurosci.5168-09.2010
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发表时间：
2010-05-12
期刊：
影响因子：
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通讯作者：
von der Heydt R
中科院分区：
文献类型：
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作者：
Zhang NR;von der Heydt R
视觉皮质中的大多数神经元对对比边界做出反应，并具有方向选择性，有些神经元还对边界的哪一边是图形，哪一边是地面(边界所有权编码)进行了选择。这些神经元受到图像背景的影响远远超出经典的感受野(CRF)，早在皮质活动开始后25ms就会受到影响。快速上下文整合机制的本质还没有被很好地理解。图形的哪些部分对语境效应有贡献？“超经典环绕”的结构是什么？背景信息是通过皮质内的水平纤维传播的，还是通过较高水平区域的相互连接传播的？为了解决这些问题，我们用零散的数字研究了边界所有权的调制。在行为诱导注视下，在恒河猴的V1和V2区记录到神经元。测试数据是零碎的矩形。虽然一边位于CRF的中心，但CRF外的碎片的存在是不同的。周围碎片对首选边界所有权一侧产生促进作用，对非首选一侧产生抑制作用，平均约80%的位置起作用。即使在没有靠近CRF的碎片的情况下，远离CRF的碎片也会影响反应，并且没有通过水平纤维传播所引起的额外延迟。讨论了三种主要不同的模型。结果支持一个模型，在该模型中，对抗性环绕影响是由来自更高水平区域的折返信号产生的。
Most neurons in visual cortex respond to contrast borders and are orientation selective, and some are also selective for which side of a border is figure and which side is ground (‘border ownership coding’). These neurons are influenced by the image context far beyond the classical receptive field (CRF), and as early as 25ms after the onset of activity in the cortex. The nature of the fast context integration mechanism is not well understood. What parts of a figure contribute to the context effect? What is the structure of the ‘extra-classical surround’? Is the context information propagated through horizontal fibers within cortex, or through reciprocal connections via higher-level areas? To address these questions we studied border ownership modulation with fragmented figures. Neurons were recorded in areas V1 and V2 of macaca mulatta under behaviorally induced fixation. Test figures were fragmented rectangles. While one edge was centered on the CRF, the presence of the fragments outside the CRF was varied. The surround fragments produced facilitation on the preferred border ownership side as well as suppression on the non-preferred side, with about 80% of the locations contributing on average. Fragments far from the CRF influenced the responses even in the absence of fragments closer to the CRF, and without the extra delay that would incur from propagation through horizontal fibers. Three principally different models are discussed. The results support a model in which the antagonistic surround influences are produced by reentrant signals from a higher-level area.