Kamermans M, Kraaij D A, Spekreijse H
Graduate School Neurosciences Amsterdam, Academic Medical Centre, University of Amsterdam, The Netherlands.
Vis Neurosci. 1998 Sep-Oct;15(5):787-97. doi: 10.1017/s0952523898154172.
Color vision is spectrally opponent, suggesting that spectrally opponent neurons, such as the horizontal cells in fish and turtle retinae, play a prominent role in color discrimination. In the accompanying paper (Kraaij et al., 1998), it was shown that the output signal of the horizontal cell system to the cones is not at all spectrally opponent. Therefore, a role for the spectrally opponent horizontal cells in color discrimination seems unlikely. In this paper, we propose that the horizontal cells play a prominent role in color constancy and simultaneous color contrast instead of in color discrimination. We have formulated a model of the cone/horizontal cell network based on measurements of the action spectra of the cones and of the feedback signal of the horizontal cell system to the various cone types. The key feature of the model is (1) that feedback is spectrally and spatially very broad and (2) that the gain of the cone synapse strongly depends on the feedback strength. This makes the synaptic gain of the cones strongly dependent on the spectral composition of the surround. Our model, which incorporates many physiological details of the outer retina, displays a behavior that can be interpreted as color constancy and simultaneous color contrast. We propose that the horizontal cell network modulates the cone synaptic gains such that the ratios of the cone outputs become almost invariant with the spectral composition of the global illumination. Therefore, color constancy appears to be coded in the retina.
颜色视觉在光谱上是拮抗的，这表明光谱拮抗神经元，如鱼类和龟类视网膜中的水平细胞，在颜色辨别中起重要作用。在随附的论文（Kraaij等人，1998年）中，已表明水平细胞系统向视锥细胞的输出信号在光谱上根本不是拮抗的。因此，光谱拮抗的水平细胞在颜色辨别中似乎不太可能起作用。在本文中，我们提出水平细胞在颜色恒常性和同时颜色对比中起重要作用，而不是在颜色辨别中。我们基于对视锥细胞的作用光谱以及水平细胞系统向各种视锥细胞类型的反馈信号的测量，构建了一个视锥细胞/水平细胞网络模型。该模型的关键特征是：（1）反馈在光谱和空间上非常广泛；（2）视锥细胞突触的增益强烈依赖于反馈强度。这使得视锥细胞的突触增益强烈依赖于周围环境的光谱组成。我们的模型纳入了外视网膜的许多生理细节，表现出一种可解释为颜色恒常性和同时颜色对比的行为。我们提出水平细胞网络调节视锥细胞的突触增益，使得视锥细胞输出的比率几乎不随全局照明的光谱组成而变化。因此，颜色恒常性似乎是在视网膜中编码的。
