Morrone C, Porciatti V, Fiorentini A, Burr D C
Istituto di Neurofisiologia del CNR, Pisa, Italy.
Vis Neurosci. 1994 Sep-Oct;11(5):861-71. doi: 10.1017/s0952523800003825.
We have studied the steady-state PERG in human subjects in response to red-green plaid patterns modulated either in luminance or in chromaticity or both. By varying the relative luminance of the red and green components, a value could be obtained at which the PERG amplitude was either minimum or locally maximum. This always occurred at equiluminance, as measured by standard psychophysical techniques. PERG amplitude and phase were measured as a function of spatial and temporal frequency of sinusoidal contrast reversal. In both space and time, the response to chromatic patterns was low-pass, while that to luminance was band-pass, and extended to higher spatial and temporal frequencies. The phase of the PERG to chromatic stimuli was systematically lagged compared with that to luminance stimuli, by an amount corresponding to about 20 ms under our experimental conditions. The variation of phase with temporal frequency suggested an apparent latency of about 67 ms for color contrast compared with 47 ms for luminance. These estimates were confirmed with separate measurements of transient PERGs to abrupt contrast reversal. For both luminance and chromatic stimuli, the amplitude of PERGs increases with increasing stimulus contrast. By summing vectorially the responses to appropriate luminance and chromatic contrasts, we were able to predict with accuracy the response as a function of color ratio (ratio of red to total luminance). The above findings all agree with those reported in the accompanying paper for the monkey PERG (Morrone et al., 1994), and indicate that the differences in response latency and integration time of luminance and chromatic stimuli observed by psychophysical and VEP techniques may arise at least in part from the properties of retinal mechanisms.
我们研究了人类受试者对亮度、色度或两者均被调制的红-绿格子图案的稳态图形视网膜电图（PERG）。通过改变红色和绿色成分的相对亮度，可以获得一个使PERG振幅最小或局部最大的值。这总是发生在通过标准心理物理学技术测量的等亮度时。测量了PERG振幅和相位作为正弦对比度反转的空间和时间频率的函数。在空间和时间上，对色度图案的反应是低通的，而对亮度的反应是带通的，并且延伸到更高的空间和时间频率。与对亮度刺激的反应相比，PERG对色度刺激的相位系统性滞后，在我们的实验条件下，滞后量约为20毫秒。相位随时间频率的变化表明，颜色对比度的明显潜伏期约为67毫秒，而亮度对比度的潜伏期为47毫秒。这些估计通过对突然对比度反转的瞬态PERG的单独测量得到了证实。对于亮度和色度刺激，PERG的振幅都随着刺激对比度的增加而增加。通过对适当的亮度和色度对比度的反应进行矢量求和，我们能够准确预测作为颜色比（红色与总亮度之比）函数的反应。上述所有发现均与随附论文中关于猴子PERG的报告（Morrone等人，1994年）一致，并表明通过心理物理学和视觉诱发电位（VEP）技术观察到的亮度和色度刺激在反应潜伏期和整合时间上的差异可能至少部分源于视网膜机制的特性。
