Disparity-based coding of three-dimensional surface orientation by macaque middle temporal neurons
Disparity-based coding of three-dimensional surface orientation by macaque middle temporal neurons
复制标题
DOI：
10.1523/jneurosci.23-18-07117.2003
复制
发表时间：
2003-08-06
影响因子：
5.3
通讯作者：
DeAngelis, GC
中科院分区：
文献类型：
--
作者：
Nguyenkim, JD;DeAngelis, GC
双眼视差在整个视野中的分量为场景中表面的三维（3-D）取向提供了有力的线索。最近在顶叶皮层中描述了由视差梯度定义的3-D表面取向的神经元选择性，但是对于这种选择性在视觉通路中的位置和方式知之甚少。由于中颞区（MT）以前曾涉及深度知觉，我们测试了MT神经元是否可以发出信号的3-D方向（参数化的倾斜和倾斜）的平面表面所描绘的随机点立体图包含一个线性梯度的水平差异。我们发现，许多MT神经元调谐为3-D表面取向，倾斜和倾斜一般有独立的影响MT响应。这种倾斜和倾斜的可分离编码让人想起其他区域中变量的联合编码（例如，例如，在一个实施例中，V1中的方向和空间频率）。我们表明，倾斜调谐保持不变时，所有的相干运动被删除的视觉刺激，表明倾斜的选择性不是一个副产品的3-D速度编码。此外，倾斜调谐通常对梯度刺激的平均视差（深度）的变化不敏感，这表明倾斜调谐不能用传统的波前视差调谐来解释。最后，我们探讨了3-D表面取向的选择性的感受野机制，我们表明，倾斜调谐产生通过异构差异MT神经元的感受野内的调谐。我们的研究结果表明，MT神经元进行高层次的信号三维表面结构，除了编码视网膜图像速度。
Gradients of binocular disparity across the visual field provide a potent cue to the three-dimensional (3-D) orientation of surfaces in a scene. Neurons selective for 3-D surface orientation defined by disparity gradients have recently been described in parietal cortex, but little is known about where and how this selectivity arises within the visual pathways. Because the middle temporal area (MT) has previously been implicated in depth perception, we tested whether MT neurons could signal the 3-D orientation (as parameterized by tilt and slant) of planar surfaces that were depicted by random-dot stereograms containing a linear gradient of horizontal disparities. We find that many MT neurons are tuned for 3-D surface orientation, and that tilt and slant generally have independent effects on MT responses. This separable coding of tilt and slant is reminiscent of the joint coding of variables in other areas (e. g., orientation and spatial frequency in V1). We show that tilt tuning remains unchanged when all coherent motion is removed from the visual stimuli, indicating that tilt selectivity is not a byproduct of 3-D velocity coding. Moreover, tilt tuning is typically insensitive to changes in the mean disparity (depth) of gradient stimuli, indicating that tilt tuning cannot be explained by conventional tuning for frontoparallel disparities. Finally, we explore the receptive field mechanisms underlying selectivity for 3-D surface orientation, and we show that tilt tuning arises through heterogeneous disparity tuning within the receptive fields of MT neurons. Our findings show that MT neurons carry high-level signals about 3-D surface structure, in addition to coding retinal image velocities.