Langrová Hana, Jägle Herbert, Zrenner Eberhart, Kurtenbach Anne
University Eye Hospital, Hradec Králové, Czech RepublicCenter for Ophthalmology, University of Tübingen, Germany.
Vis Neurosci. 2007 Nov-Dec;24(6):805-16. doi: 10.1017/S0952523807070733.
The number of L cones in the retina normally exceeds that of the M cones. Because normal color vision does not depend on the ratio of L- and M-photoreceptors, their signals must undergo an alteration in gain before being analyzed in the cortex. Previous studies have shown that this gain must take place before the cortex, but after the bipolar/amacrine cell layer of the retina. The aim of this study was to obtain topographical information about L- and M-cone activity at the ganglion cell layer using multifocal pattern electroretinography (mfPERG). A standard (black and white) stimulus was used, as well as stimuli modulating only the long wavelength-sensitive (L) or only the middle wavelength-sensitive (M) cones. The L:M ratio was calculated from the amplitude of the L-cone isolating mfPERG to that of the M-cone isolating mfPERG of 10 trichromats. Both the positive and negative components of the waveform were analyzed. Additional recordings of single cone modulated mfERGs were obtained from nine of the 10 subjects. We also recorded from one protanope and one deuteranope. The L:M cone amplitude ratios for both deflections of the mfPERG in the trichromats were around unity (medians 1.18 and 1.16, respectively) for the central 8 degrees of retina. In the peripheral retina between 12.8 degrees and 26 degrees , this ratio increased to 1.42 for the positive component, and 1.37 for the negative component. The median L:M cone amplitude ratios for the mfPERG were higher and ranged between 1.00-2.78 in the central 8 degrees and 1.29-2.78 in the periphery. The results indicate that a major gain adjustment of the retinal signals takes place at the ganglion cell level, and that the ratio is higher at eccentric locations than in the central retinal area.
视网膜中L视锥细胞的数量通常超过M视锥细胞。由于正常的色觉并不取决于L和M光感受器的比例，它们的信号在进入皮层进行分析之前必须进行增益改变。先前的研究表明，这种增益改变必须在皮层之前、视网膜双极/无长突细胞层之后发生。本研究的目的是使用多焦图形视网膜电图（mfPERG）获取神经节细胞层L和M视锥细胞活动的地形图信息。使用了标准（黑白）刺激，以及仅调制长波长敏感（L）或仅调制中波长敏感（M）视锥细胞的刺激。从10名三色视者的L视锥细胞分离mfPERG的振幅与M视锥细胞分离mfPERG的振幅计算L:M比值。对波形的正、负成分均进行了分析。从10名受试者中的9名获得了单视锥细胞调制mfERG的额外记录。我们还记录了一名红色盲和一名绿色盲患者的情况。对于三色视者，视网膜中央8度区域mfPERG两个偏转的L:M视锥细胞振幅比值均约为1（中位数分别为1.18和1.16）。在视网膜12.8度至26度的周边区域，该比值对于正成分增加到1.42，对于负成分增加到1.37。mfPERG的L:M视锥细胞振幅比值中位数更高，在中央8度区域范围为1.00 - 2.78，在周边区域为1.29 - 2.78。结果表明，视网膜信号的主要增益调整发生在神经节细胞水平，且该比值在偏心位置高于视网膜中央区域。
