Representation of stereoscopic depth based on relative disparity in macaque area V4
Representation of stereoscopic depth based on relative disparity in macaque area V4
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DOI：
10.1152/jn.01336.2006
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发表时间：
2007-07-01
影响因子：
2.5
通讯作者：
Fujita, Ichiro
中科院分区：
文献类型：
--
作者：
Umeda, Kazumasa;Tanabe, Seiji;Fujita, Ichiro
当背景特征作为参考时，立体视觉的特征是视觉敏锐度更高。当存在参照时，物体的感知深度主要取决于该参照。立体深度的神经表示应该有一个相对的参照系。在区域V1中编码的绝对视差到相对视差的转换在区域V2中开始，尽管在该区域中编码的信息似乎不足以进行立体视觉。这项研究考察了相对视差是否编码在较高的皮质区域。我们记录了猕猴V4神经元对两个特征的绝对差异的不同组合的反应：动态随机点立体图的中心斑块和周围环。我们分析了周围环的视差对中心片视差调谐的影响；相对视差选择神经元对中心片视差的调谐曲线应该随着周围环的视差的变化而移动。大多数V4调谐曲线显示出明显的移位。移位的幅度大于V2神经元的报道，小于理想的相对视差选择性细胞的预期。没有发现移位幅度与尺寸抑制程度之间的相关性，这表明这两种现象不是共同机制的结果。我们的结果表明，当信息沿着包括V2和V4区的皮质通路流动时，相对视差的编码向前推进。
Stereoscopic vision is characterized by greater visual acuity when a background feature serves as a reference. When a reference is present, the perceived depth of an object is predominantly dependent on this reference. Neural representations of stereoscopic depth are expected to have a relative frame of reference. The conversion of absolute disparity encoded in area V1 to relative disparity begins in area V2, although the information encoded in this area appears to be insufficient for stereopsis. This study examines whether relative disparity is encoded in a higher cortical area. We recorded the responses of V4 neurons from macaque monkeys to various combinations of the absolute disparities of two features: the center patch and surrounding annulus of a dynamic random-dot stereogram. We analyzed the effects of the disparity of the surrounding annulus on the tuning for the disparity of the center patch; the tuning curves of relative-disparity-selective neurons for disparities of the center patch should shift with changes in the disparity of the surrounding annulus. Most V4 tuning curves exhibited significant shifts. The magnitudes of the shifts were larger than those reported for V2 neurons and smaller than that expected for an ideal relative-disparity-selective cell. No correlation was found between the shift magnitude and the degree of size suppression, suggesting that the two phenomena are not the result of a common mechanism. Our results suggest that the coding of relative disparity advances as information flows along the cortical pathway that includes areas V2 and V4.