Freeman A W
Department of Physiology F13, University of Sydney, N.S.W., Australia.
Vision Res. 1991;31(5):775-85. doi: 10.1016/0042-6989(91)90146-v.
Impulse rate was recorded from X- and Y-type ganglion cells in the cat's retina. The stimuli were stationary gratings for which luminance varied sinusoidally with distance across the stimulus, and amplitude varied sinusoidally in time. Y cell fundamental and second harmonic responses recorded at medium to high spatial frequencies advanced in phase with increasing contrast, an effect attributable to the contrast gain control. As spatial frequency increased to the highest value capable of evoking a second harmonic response, the phase of this response became retarded, indicating that the contrast gain control was losing its effect. This result showed that the spatial resolution of the contrast gain control is very close to that of the Y cell's rectifying subunits. The observations strongly suggest that the contrast gain control has its effect early in retinal image processing.
记录了猫视网膜中X型和Y型神经节细胞的脉冲频率。刺激物是静止光栅，其亮度随刺激物上距离呈正弦变化，幅度随时间呈正弦变化。在中高空间频率下记录的Y细胞基波和二次谐波反应随着对比度增加而相位提前，这种效应归因于对比度增益控制。当空间频率增加到能够引发二次谐波反应的最高值时，该反应的相位延迟，表明对比度增益控制正在失去其作用。这一结果表明，对比度增益控制的空间分辨率与Y细胞整流亚基的空间分辨率非常接近。这些观察结果强烈表明，对比度增益控制在视网膜图像处理的早期就起作用。
