Three-dimensional visual information processing in the parietal cortex

为了阐明参与表面三维（3D）方向感知的神经机制，我们训练猴子使用Go/No-go型延迟匹配样本（DMTS）任务区分表面的3D方向和双眼视差线索，并检查表面方向选择（SOS）神经元的特性。我们记录SOS神经元的尾侧部分的外侧银行的顶内沟（CIP区）的日本猴（猕猴fuscata）。我们测试SOS神经元使用的正方形板的立体图（SFS）和随机点立体图（RDS）没有透视线索，几乎所有的测试神经元显示表面取向选择性的SFS和/或RDS没有透视线索。这些结果表明，在没有透视线索的情况下，对RDS表现出表面方向调节的神经元根据双眼视差的梯度计算表面方向，而表现出表面方向调节的神经元 ...更多信息 对于没有透视线索的SFS，可以主要根据双眼视差的梯度沿着轮廓表示表面取向。此外，我们研究了线性透视线索对SOS神经元反应的影响。神经元的测试使用单独的透视线索的固体图。超过一半的被测神经元对视角和视差线索都敏感，但也有少数神经元只对视角线索敏感。立体图形的反应强度与视角线索单独弱于视差线索，这表明整合的表面方向的知觉线索，但视差线索的优势。我们还测试了纹理梯度的效果。许多神经元对纹理梯度敏感，其中一半以上的神经元对视差梯度也敏感，表明纹理梯度信息与CIP区域的视差梯度相结合。这些结果表明，单目深度线索与CIP区域的视差线索相结合，建立了独立于信息来源的表面方向的广义表示。最后，使用功能性磁共振成像（fMRI）检查皮层活动，而受试者区分是否中央部分的表面是突出或凹陷的基础上没有任何双目视差线索和右顶内区的阴影被激活。这一结果有力地表明，顶内区起着重要的作用，在知觉的三维结构的表面，即使是基于只有单眼的深度线索，没有双眼视差cooks.In结论，SOS神经元在CIP区可能操作高阶处理的视差信号的表面知觉，通过整合的几种深度线索。少

In order to elucidate the neural mechanisms involved in the perception of the three-dimensional (3D) orientation of a surface, we trained monkeys to discriminate the 3D orientation of a surface from binocular disparity cues using a Go/No-go type delayed-matching-to-sample (DMTS) task and examined the properties of the surface-orientation-selective (SOS) neurons. We recorded SOS neurons from the caudal part of the lateral bank of the intraparietal sulcus (area CIP) of Japanese monkeys (Macaca fuscata). We tested SOS neurons using the square plate of a solid figure stereogram (SFS) and random-dot stereogram (RDS) without perspective cues ; almost all of tested neurons showed surface orientation selectivity for the SFS and/or the RDS without perspective cues. These results suggest that neurons which show surface orientation tuning for the RDS without perspective cues compute surface orientation from the gradient of the binocular disparity and neurons which show surface orientation tuning … More for the SFS without perspective cues may represent surface orientation primarily from the gradient of the binocular disparity along the contours. Furthermore, we investigated the effects of linear perspective cues on the response of SOS neurons. Neurons were tested using the solid figure with perspective cues alone. More than half of tested neurons were sensitive to both perspective and disparity cues, but a few were sensitive to perspective cues alone. The response magnitude to the solid figure with perspective cues alone was weaker than that with disparity cues, suggesting the integration of both cues for the perception of surface orientation, however, the dominance of disparity cues. We also tested the effects of texture gradient. Many neurons were sensitive to the texture gradient, and more than half of them were also sensitive to the disparity gradient, suggesting that texture gradient information is integrated with disparity gradient in area CIP.These results suggest that the monocular depth cues are integrated with the disparity cues in area CIP to build up a generalized representation of surface orientation independent of the source of information. Finally, cortical activities were examined using functional magnetic resonance imaging (fMRI) while subjects discriminated whether the central part of the surface was protruded or recessed based on shading without any binocular disparity cues and the right intraparietal area was shown to be activated. This result strongly suggests that the intraparietal area plays an important role in perception of a 3D structure of a surface, even when based only on monocular depth cues without binocular disparity cues.In conclusion, the SOS neurons in the area CIP are likely to operate higher order processing of disparity signals for surface perception by integrating the several kinds of depth cues. Less