Baker C L, Friend S M, Boulton J C
Department of Psychology, McGill University, Canada.
Vision Res. 1991;31(10):1659-68. doi: 10.1016/0042-6989(91)90017-y.
Responses of single neurons in cat visual cortex were measured in response to sinewave grating stimuli. Firstly, a neuron's spatial frequency tuning was determined, and subsequent stimuli were set at the optimal spatial frequency for that neuron. Then a "jumping grating" stimulus was used: a sinewave grating subjected to a series of abrupt spatial displacements, while remaining stationary for a fixed exposure time between displacements. The amount of direction selectivity elicited by this stimulus was measured as a function of the amount of spatial displacement. Visual cortex neurons generally showed an optimal spatial displacement, corresponding to somewhat less than one quarter of a spatial period of the neuron's optimal spatial frequency (close to, but systematically less than, "quadrature phase"). In a majority of neurons tested, this optimal displacement was not affected by increasing the exposure time between displacements, indicating that the measurements were not a simple consequence of temporal frequency tuning. These results closely parallel recent human psychophysical data obtained from measurements of motion aftereffect or direction discrimination elicited by jumping grating stimuli.
在猫视觉皮层中，测量单个神经元对正弦波光栅刺激的反应。首先，确定神经元的空间频率调谐，随后的刺激设置为该神经元的最佳空间频率。然后使用“跳跃光栅”刺激：一个正弦波光栅经历一系列突然的空间位移，同时在位移之间保持固定的曝光时间静止不动。测量此刺激引发的方向选择性量作为空间位移量的函数。视觉皮层神经元通常表现出最佳空间位移，对应于略小于神经元最佳空间频率空间周期的四分之一（接近但系统地小于“正交相位”）。在大多数测试的神经元中，这种最佳位移不受位移之间曝光时间增加的影响，表明测量结果不是时间频率调谐的简单结果。这些结果与最近通过跳跃光栅刺激引发的运动后效或方向辨别测量获得的人类心理物理学数据非常相似。
