Heider B, Meskenaite V, Peterhans E
Department of Neurology, University Hospital Zurich, CH-8091 Zurich, Switzerland.
Eur J Neurosci. 2000 Nov;12(11):4117-30. doi: 10.1046/j.1460-9568.2000.00293.x.
We studied the anatomy and physiology of neurons in monkey visual cortex, which contribute to mechanisms segregating figure and ground at contours based on information provided by occlusion cues. First, we defined the location of neurons sensitive to occluding (illusory) contours. These neurons were found most frequently in the pale cytochrome oxidase stripes of area V2 but rarely in V1. In area V2, they were found in all laminae and with similar frequencies. The few neurons recorded in area V1 concentrated in the upper laminae. Second, we studied the properties and anatomical location of neurons sensitive to occlusion cues (dark and light line-ends, corners). These neurons had end-stopped receptive fields and were found with similar frequencies in both areas. In area V1, they concentrated in the upper laminae. In area V2, they were found in all laminae and cytochrome oxidase stripes. These neurons responded to short stimuli of optimal length (bars, edges) and to stimuli terminating in their receptive field (line-ends, corners). Overall, about half of these neurons detected the direction of such terminations and about 60% were selective for certain types of termination. In summary, our results suggest that in monkey visual cortex, occlusion cues are represented in areas V1 and V2, whereas grouping mechanisms detecting occluding contours concentrate in area V2.
我们研究了猴视觉皮层中神经元的解剖结构和生理功能，这些神经元基于遮挡线索提供的信息，参与了在轮廓处分离图形和背景的机制。首先，我们确定了对遮挡（虚幻）轮廓敏感的神经元的位置。这些神经元最常见于V2区的淡细胞色素氧化酶条带中，但在V1区很少见。在V2区，它们在所有层中均有发现，且频率相似。在V1区记录到的少数神经元集中在上层。其次，我们研究了对遮挡线索（暗线端和亮线端、角）敏感的神经元的特性和解剖位置。这些神经元具有终端停止的感受野，在两个区域中的出现频率相似。在V1区，它们集中在上层。在V2区，它们在所有层和细胞色素氧化酶条带中均有发现。这些神经元对最佳长度的短刺激（条、边缘）以及在其感受野中终止的刺激（线端、角）有反应。总体而言，这些神经元中约一半能检测到此类终止的方向，约60%对某些类型的终止具有选择性。总之，我们的结果表明，在猴视觉皮层中，遮挡线索在V1区和V2区均有表征，而检测遮挡轮廓的分组机制集中在V2区。
