Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center , Omaha, Nebraska ; and Department of Biological Structure, Washington National Primate Research Center, University of Washington , Seattle, Washington.
Physiol Rev. 2019 Jul 1;99(3):1527-1573. doi: 10.1152/physrev.00027.2018.
Synaptic interactions to extract information about wavelength, and thus color, begin in the vertebrate retina with three classes of light-sensitive cells: rod photoreceptors at low light levels, multiple types of cone photoreceptors that vary in spectral sensitivity, and intrinsically photosensitive ganglion cells that contain the photopigment melanopsin. When isolated from its neighbors, a photoreceptor confounds photon flux with wavelength and so by itself provides no information about color. The retina has evolved elaborate color opponent circuitry for extracting wavelength information by comparing the activities of different photoreceptor types broadly tuned to different parts of the visible spectrum. We review studies concerning the circuit mechanisms mediating opponent interactions in a range of species, from tetrachromatic fish with diverse color opponent cell types to common dichromatic mammals where cone opponency is restricted to a subset of specialized circuits. Distinct among mammals, primates have reinvented trichromatic color vision using novel strategies to incorporate evolution of an additional photopigment gene into the foveal structure and circuitry that supports high-resolution vision. Color vision is absent at scotopic light levels when only rods are active, but rods interact with cone signals to influence color perception at mesopic light levels. Recent evidence suggests melanopsin-mediated signals, which have been identified as a substrate for setting circadian rhythms, may also influence color perception. We consider circuits that may mediate these interactions. While cone opponency is a relatively simple neural computation, it has been implemented in vertebrates by diverse neural mechanisms that are not yet fully understood.
脊椎动物视网膜中的三种感光细胞（对弱光敏感的视杆细胞、对光谱敏感程度不同的多种视锥细胞和含有光色素黑视蛋白的光敏感神经节细胞）通过突触相互作用来提取关于波长的信息，从而感知颜色。当感光细胞与周围的细胞分离时，它会将光通量与波长混淆，因此本身无法提供有关颜色的任何信息。视网膜已经进化出了复杂的色彩拮抗电路，通过比较对可见光谱不同部分广泛调谐的不同感光细胞类型的活动，来提取波长信息。我们回顾了一系列物种中介导拮抗相互作用的电路机制的研究，从具有多种色彩拮抗细胞类型的四色鱼类到圆锥体拮抗作用仅限于特定专门电路的常见双色哺乳动物。在哺乳动物中，灵长类动物通过将额外的光色素基因纳入支持高分辨率视觉的中央凹结构和电路中，以新颖的策略重新创造了三色视觉。当只有视杆细胞活跃时，在暗视水平下没有色觉，但视杆细胞与视锥细胞信号相互作用，影响中间视觉水平的色觉。最近的证据表明，黑视蛋白介导的信号可能也会影响色觉，这些信号已被确定为调节昼夜节律的基础。我们考虑了可能介导这些相互作用的电路。虽然圆锥体拮抗作用是一种相对简单的神经计算，但它已通过脊椎动物中尚未完全理解的各种神经机制来实现。
