Klistorner A, Crewther D P, Crewther S G
School of Optometry, University of New South Wales, Sydney, Australia.
Vision Res. 1998 Dec;38(24):3979-4000. doi: 10.1016/s0042-6989(97)00394-5.
Temporal analysis of the chromatic flash visual evoked potential (VEP) was studied in human subjects with normal and anomalous colour vision using a deterministic pseudo-random binary stimulus (VERIS). Five experiments were carried out on four normal subjects investigating heterochromatic red-green exchange and single colour/achromatic (either red/grey or green/grey) exchange over a wide range of luminance ratios for the two stimuli, the effects of lowered mean luminance on the chromatic VEP and the effects of colour desaturation at constant mean luminance and constant luminance contrast. Finally, the performance of three dichromats, a protanope and two deuteranopes, on heterochromatic exchange VEP and on colour desaturation were investigated. In contrast to the chromatic electroretinogram, which shows great symmetry with respect to luminance ratio on opposite sides of the isoluminant point, the chromatic VEP demonstrated a distinct asymmetry when the colours exchanged included red. On the red side of isoluminance (red more luminant than green), a wave with longer latency and altered waveform became dominant. The effects of green stimulation were indistinguishable from those of achromatic stimulation at the same luminance contrast over the whole range of chromatic contrast and for all levels of desaturation studied. Desaturation of red with constant luminance contrast (desaturated red/grey stimulation) resulted in a systematic alteration in the evoked waveform. Subtraction of the achromatic first- and second-order responses from responses recorded in the red desaturation series resulted in remarkably uniform waveforms, with peak amplitudes growing linearly with saturation. The absence of interaction between achromatic and coloured components for all (including the most intense colour) stimulus parameters used suggests that the generators of these components are separate. Recordings from the dichromats showed that the contrast response minimum shifted from the point of photopic isoluminance to the point of zero cone contrast (at the silent substitution point) for the remaining cone type. The waveforms recorded with a series of luminance ratios were much simpler than those recorded from trichromats and symmetrical with respect to their isoluminant points. Despite the indication of the presence of L cones of apparently normal spectral sensitivity in the deuteranopes (on the basis of flicker photometry), there was no evidence for a red-sensitive component in the desaturation or heterochromatic stimulation series. The results are discussed in terms of the possibility of separate generation of chromatic and achromatic contributions to the VEP.
使用确定性伪随机二进制刺激（VERIS）对具有正常和异常色觉的人类受试者的彩色闪光视觉诱发电位（VEP）进行了时间分析。对四名正常受试者进行了五项实验，研究了两种刺激在广泛的亮度比范围内的异色红-绿交换和单色/消色差（红/灰或绿/灰）交换、降低平均亮度对彩色VEP的影响以及在恒定平均亮度和恒定亮度对比度下颜色去饱和的影响。最后，研究了三名二色视者（一名红色盲和两名绿色盲）在异色交换VEP和颜色去饱和方面的表现。与彩色视网膜电图不同，彩色视网膜电图在等亮度点两侧的亮度比方面表现出很大的对称性，当交换的颜色包括红色时，彩色VEP表现出明显的不对称性。在等亮度的红色一侧（红色比绿色更亮），一个潜伏期更长且波形改变的波占主导地位。在整个彩色对比度范围内以及所研究的所有去饱和水平下，在相同亮度对比度下，绿色刺激的效果与消色差刺激的效果无法区分。在恒定亮度对比度下红色去饱和（去饱和红/灰刺激）导致诱发波形的系统性改变。从红色去饱和系列记录的反应中减去消色差的一阶和二阶反应，得到的波形非常均匀，峰值幅度随饱和度呈线性增长。对于所有使用的（包括最强颜色的）刺激参数，消色差和彩色成分之间不存在相互作用，这表明这些成分的发生器是分开的。二色视者的记录表明，对于剩余的视锥类型，对比度反应最小值从明视觉等亮度点转移到零视锥对比度点（在无声替代点）。用一系列亮度比记录的波形比从三色视者记录的波形简单得多，并且相对于它们的等亮度点是对称的。尽管根据闪烁光度法表明绿色盲者中存在光谱敏感性明显正常的L视锥，但在去饱和或异色刺激系列中没有证据表明存在对红色敏感的成分。根据对VEP的彩色和消色差贡献可能分开产生的可能性对结果进行了讨论。
