Binocular spatial phase tuning characteristics of neurons in the macaque striate cortex
Binocular spatial phase tuning characteristics of neurons in the macaque striate cortex
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DOI：
10.1152/jn.1997.78.1.351
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发表时间：
1997-07-01
影响因子：
2.5
通讯作者：
Crawford, MLJ
中科院分区：
文献类型：
--
作者：
Smith, EL;Chino, YM;Crawford, MLJ
我们使用微电极记录技术来研究麻醉和瘫痪猕猴纹状皮质中单个神经元对相对眼间图像差异的敏感性，并确定基本刺激参数对这些皮质双眼相互作用的影响。视觉刺激为漂移的正弦波栅。在找到最优刺激方向、空间频率和刺激运动方向后，通过测量作为双眼光栅对的相对眼间空间相位的响应来确定细胞的视差调谐特性。没有人试图评估绝对位置差异或相对于星座的水平差异。大多数(类似于70%)的简单细胞对眼间空间位相差异高度敏感，尤其是具有平衡眼优势的神经元。单纯细胞在最佳相位视差时表现出双眼促进作用，而180度外的视差表现为双眼抑制。具有相选择性的复杂细胞较少(接近40%)；然而，相敏感的复杂细胞的差异选择性范围与简单细胞相当。双眼反应幅度不同于对单眼刺激的反应，这证明了非相位敏感复杂细胞中的双眼相互作用。视差调谐的程度与细胞的最佳取向或方向调谐的程度无关。然而，视差敏感细胞倾向于具有较窄的方向调节功能，并且最优刺激方向的视差调节程度最大。将一只眼睛的刺激从最佳方向旋转90度，通常会消除双眼的相互作用。在最佳空间频率下，相位差对双眼反应幅度的影响也最大。因此，细胞对绝对位置差异的敏感性反映了它的空间调谐特征，对高空间频率敏感的细胞能够发出图像差异非常小的变化的信号。另一方面，刺激对比度对细胞视差调节的影响相对较小，因为对于所有相对的眼间相位差异，反应饱和发生在相同的对比度水平上。因此，就像定向调节一样，细胞的最佳视差和视差选择性程度不随对比度而变化。总体而言，结果表明，对眼睛间空间相位差异的敏感性是纹状神经元的共同属性。细胞的视差调节特性似乎在很大程度上反映了它的单眼感受野特性以及兴奋性和抑制性输入之间的眼间平衡。然而，仅凭视差敏感度不能区分不同功能类别的皮质神经元。
We employed microelectrode recording techniques to study the sensitivity of individual neurons in the striate cortex of anesthetized and paralyzed monkeys to relative interocular image disparities and to determine the effects of basic stimulus parameters on these cortical binocular interactions. The visual stimuli were drifting sine wave gratings. After the optimal stimulus orientation, spatial frequency, and direction of stimulus movement were found, the cells' disparity tuning characteristics were determined by measuring responses as a function of the relative interocular spatial phase of dichoptic grating pairs. No attempts were made to assess absolute position disparities or horizontal disparities relative to the horopter. The majority (similar to 70%) of simple cells were highly sensitive to interocular spatial phase disparities, particularly neurons with balanced ocular dominances. Simple cells typically demonstrated binocular facilitation at the optimal phase disparity and binocular suppression for disparities 180 degrees away. Fewer complex cells were phase selective (similar to 40%); however, the range of disparity selectivity in phase-sensitive complex cells was comparable with that for simple cells. Binocular interactions in non-phase-sensitive complex cells were evidenced by binocular response amplitudes that differed from responses to monocular stimulation. The degree of disparity tuning was independent of a cell's optimal orientation or the degree of direction tuning. However, disparity-sensitive cells tended to have narrow orientation tuning functions and the degree of disparity tuning was greatest for the optimal stimulus orientations. Rotating the stimulus for one eye 90 degrees from the optimal orientation usually eliminated binocular interactions. The effects of phase disparities on the binocular response amplitude were also greatest at the optimal spatial frequency. Thus a cell's sensitivity to absolute position disparities reflects its spatial tuning characteristics, with cells sensitive to high spatial frequencies being capable of signaling very small changes in image disparity. On the other hand, stimulus contrast had relatively little effect on a cell's disparity tuning, because response saturation occurred at the same contrast level for all relative interocular phase disparities. Thus, as with orientation tuning, a cell's optimal disparity and the degree of disparity selectivity were invariant with contrast. Overall, the results show that sensitivity to interocular spatial phase disparities is a common property of striate neurons. A cell's disparity tuning characteristics appear to largely reflect its monocular receptive field properties and the interocular balance between excitatory and inhibitory inputs. However, distinct functional classes of cortical neurons could not be discriminated on the basis of disparity sensitivity alone.