Kremers J, Usui T, Scholl H P, Sharpe L T
Department of Experimental Ophthalmology, University Eye Hospital, Tübingen, Germany.
Invest Ophthalmol Vis Sci. 1999 Apr;40(5):920-30.
To find out how the different cone types contribute to the electroretinogram (ERG) by quantifying the contribution of the signal pathways originating in the long (L-) and the middle (M-) wavelength-sensitive cones to the total ERG response amplitude and phase.
ERG response amplitudes and phases were measured to cone-isolating stimuli and to different combinations of L- and M-cone modulation. Conditions were chosen to exclude any contribution of the short wavelength-sensitive (S-) cones. The sensitivity of the ERG to the L and the M cones was defined as the cone contrast gain.
In the present paper, a model is provided that describes the ERG contrast gains and ERG thresholds in dichromats and color normal trichromats. For the X-chromosome-linked dichromats, the contrast gains of only one cone type (either the L or the M cones) sufficed to describe the ERG thresholds for all stimulus conditions. Data suggest that the M-cone contrast gains of protanopes are larger than the L-cone contrast gains of deuteranopes. The response thresholds of the trichromats are modeled by assuming a vector summation of signals originating in the L and the M cones. Their L- and M-cone contrast gains are close to a linear interpolation of the data obtained from the dichromats. Nearly all trichromats had larger L- than M-cone contrast gains. Data from a large population of trichromats were examined to study the individual variations in cone weightings and in the phases of the cone pathway responses.
The data strongly suggest that the missing cone type in dichromats is replaced by the remaining cone type. The mean L-cone to M-cone weighting ratio in trichromats was found to be approximately 4:1. But there is a substantial interindividual variability between trichromats. The response phases of the L- and the M-cone pathways can be reliably quantified using the response phases to the cone-isolating stimuli or using a vector addition of L- and M-cone signals.
通过量化源自长（L-）和中（M-）波长敏感视锥细胞的信号通路对总视网膜电图（ERG）反应幅度和相位的贡献，来探究不同类型视锥细胞如何对ERG产生影响。
测量ERG对视锥细胞隔离刺激以及L-和M-视锥细胞调制的不同组合的反应幅度和相位。选择相关条件以排除短波长敏感（S-）视锥细胞的任何贡献。ERG对L和M视锥细胞的敏感性被定义为视锥细胞对比度增益。
在本文中，提供了一个模型，该模型描述了二色视者和色觉正常的三色视者的ERG对比度增益和ERG阈值。对于X染色体连锁的二色视者，仅一种视锥细胞类型（L或M视锥细胞）的对比度增益就足以描述所有刺激条件下的ERG阈值。数据表明，红色盲者的M视锥细胞对比度增益大于绿色盲者的L视锥细胞对比度增益。通过假设源自L和M视锥细胞的信号进行矢量求和来模拟三色视者的反应阈值。他们的L和M视锥细胞对比度增益接近从二色视者获得的数据的线性插值。几乎所有三色视者的L视锥细胞对比度增益都大于M视锥细胞对比度增益。研究了大量三色视者的数据，以探讨视锥细胞加权和视锥细胞通路反应相位的个体差异。
数据强烈表明，二色视者中缺失的视锥细胞类型被剩余的视锥细胞类型所替代。发现三色视者中L视锥细胞与M视锥细胞的平均加权比约为4:1。但三色视者之间存在很大的个体差异。使用对视锥细胞隔离刺激的反应相位或通过L和M视锥细胞信号的矢量相加，可以可靠地量化L和M视锥细胞通路的反应相位。
