Gomes Bruno D, Souza Givago S, Lima Monica G, Rodrigues Anderson R, Saito Cézar A, da Silva Filho Manoel, Silveira Luiz Carlos L
Departamento de Fisiologia, Instituto de Ciências Biológicas, Universidade Federal do Pará, Brazil.
Vis Neurosci. 2008 May-Jun;25(3):333-9. doi: 10.1017/S0952523808080383.
The purpose of this work is to investigate the use of different forms of visual evoked potentials (VEPs) to measure color discrimination thresholds and to plot color discrimination ellipses (MacAdam, 1942). Five normal trichromats (24.5 +/- 2.6 years-old) were monocularly tested. Stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions radiating from one reference point of the CIE 1976 chromaticity diagram (u' = 0.225; v' = 0.415). Heterochromatic flicker photometry (HFP) was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. VEPs were elicited using two cycles per degree grating stimuli at three different temporal configurations: transient, onset (300 ms)/offset (700 ms), 1 Hz fundamental frequency; steady-state, onset (50 ms)/offset (50 ms), 10 Hz fundamental frequency; and steady-state pattern reversal at 5 Hz fundamental frequency (10 Hz phase reversal). VEP amplitude was measured using transient VEP N1-P1 components and steady state VEP first (10 Hz) and second (20 Hz) harmonics. VEP amplitude was plotted as a function of chromatic distance in the CIE 1976 color space and the data points were extrapolated to zero amplitude level to obtain chromatic discrimination thresholds. The results were compared with psychophysical measurements performed using the same stimulus configurations and with the pseudoisochromatic method of Mollon-Reffin (one-way ANOVA). For all subjects and all stimulation methods, the ellipses showed small sizes, low ellipticities, and were vertically oriented. Despite some consistent differences in the results obtained with different procedures, there was no statistical difference between ellipses obtained electrophysiologically and psychophysically. For steady state VEPs, ellipses obtained from second harmonic amplitudes were larger and more elongated in the tritan direction than those obtained with first harmonic amplitudes.
本研究的目的是探讨使用不同形式的视觉诱发电位（VEP）来测量颜色辨别阈值，并绘制颜色辨别椭圆（MacAdam，1942）。对5名正常三色视者（年龄24.5±2.6岁）进行单眼测试。刺激由正弦等亮度彩色光栅组成，这些光栅由位于CIE 1976色度图一个参考点（u' = 0.225；v' = 0.415）沿四个不同颜色方向辐射的色度对制成。使用异色闪烁光度法（HFP）为每个受试者和所有色度对获取等亮度条件。使用每度两个周期的光栅刺激，在三种不同的时间配置下诱发VEP：瞬态，起始（300毫秒）/偏移（700毫秒），1赫兹基频；稳态，起始（50毫秒）/偏移（50毫秒），10赫兹基频；以及5赫兹基频（10赫兹相位反转）的稳态模式反转。使用瞬态VEP的N₁ - P₁成分以及稳态VEP的一次（10赫兹）和二次（20赫兹）谐波测量VEP振幅。将VEP振幅绘制为CIE 1976颜色空间中色度距离的函数，并将数据点外推到零振幅水平以获得颜色辨别阈值。将结果与使用相同刺激配置和Mollon - Refffin假等色法进行的心理物理学测量结果进行比较（单因素方差分析）。对于所有受试者和所有刺激方法，椭圆显示尺寸小、椭圆率低且垂直定向。尽管不同程序获得的结果存在一些一致的差异，但通过电生理和心理物理学方法获得的椭圆之间没有统计学差异。对于稳态VEP，从二次谐波振幅获得的椭圆在蓝黄色方向上比从一次谐波振幅获得的椭圆更大且更细长。
