Figure and ground: how the visual cortex integrates local cues for global organization.
Figure and ground: how the visual cortex integrates local cues for global organization.
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图和底：视觉皮层如何整合局部线索以进行全局组织。
DOI：
10.1152/jn.00125.2018
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发表时间：
2018
影响因子：
2.5
通讯作者：
Zhang,NanR
中科院分区：
文献类型：
--
作者：
vonderHeydt,Rüdiger;Zhang,NanR
推断二维图像中的图形-背景组织可能需要不同的互补策略。对于孤立的物体，研究表明视觉皮层的机制会利用轮廓的整体分布，但在轮廓分组不明显的杂乱场景的图像中，该策略会失败。然而，自然场景包含局部特征，特别是轮廓交界处，这可能有助于对象区域的定义。为了研究局部特征在边界所有权分配中的作用，我们记录了清醒行为猕猴视觉皮层的单细胞活动。我们测试了被视为两个重叠图形的配置，其中 T 形和 L 形连接取决于重叠的方向，而轮廓的整体分布没有提供有效信息。在记录对遮挡轮廓的响应时，我们改变了重叠方向，并不同程度地掩盖了一些关键轮廓特征，以确定它们的影响和相互作用。平均而言，大多数功能一致地影响响应，根据边界所有权产生增强或抑制。即使在同一位置，不同的要素类型也可能产生相反的效果。远离感受野的特征产生的效果与靠近的特征一样强，并且具有相同的短延迟。求和是高度非线性的：任何单个特征产生的效果超过所有特征共同产生的效果的三分之二。这些发现揭示了快速且高度具体的组织机制，支持先前提出的模型，其中“分组细胞”将广泛分布的边缘信号与特定的末端停止信号集成，以通过反馈调制原始边缘信号。新的和值得注意的看到对象似乎毫不费力，但定义场景中的对象需要复杂的神经机制。对于孤立的物体，视觉皮层根据整体分布对轮廓进行分组，但这种策略不适用于杂乱的场景。在这里，我们演示了集成 T 形和 L 形接头等局部轮廓特征来解决混乱的机制。该过程速度快，评估广泛分布的特征，并使任何单个特征对图形-背景表示产生决定性影响。
Inferring figure-ground organization in two-dimensional images may require different complementary strategies. For isolated objects, it has been shown that mechanisms in visual cortex exploit the overall distribution of contours, but in images of cluttered scenes where the grouping of contours is not obvious, that strategy would fail. However, natural scenes contain local features, specifically contour junctions, that may contribute to the definition of object regions. To study the role of local features in the assignment of border ownership, we recorded single-cell activity from visual cortex in awake behavingMacaca mulatta. We tested configurations perceived as two overlapping figures in which T- and L-junctions depend on the direction of overlap, whereas the overall distribution of contours provides no valid information. While recording responses to the occluding contour, we varied direction of overlap and variably masked some of the critical contour features to determine their influences and their interactions. On average, most features influenced the responses consistently, producing either enhancement or suppression depending on border ownership. Different feature types could have opposite effects even at the same location. Features far from the receptive field produced effects as strong as near features and with the same short latency. Summation was highly nonlinear: any single feature produced more than two-thirds of the effect of all features together. These findings reveal fast and highly specific organization mechanisms, supporting a previously proposed model in which “grouping cells” integrate widely distributed edge signals with specific end-stopped signals to modulate the original edge signals by feedback.NEW & NOTEWORTHYSeeing objects seems effortless, but defining objects in a scene requires sophisticated neural mechanisms. For isolated objects, the visual cortex groups contours based on overall distribution, but this strategy does not work for cluttered scenes. Here, we demonstrate mechanisms that integrate local contour features like T- and L-junctions to resolve clutter. The process is fast, evaluates widely distributed features, and gives any single feature a decisive influence on figure-ground representation.