Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, United States.
Genetic Engineering Facility, National Eye Institute, National Institutes of Health, Bethesda, United States.
Elife. 2020 May 28;9:e56840. doi: 10.7554/eLife.56840.
Color, an important visual cue for survival, is encoded by comparing signals from photoreceptors with different spectral sensitivities. The mouse retina expresses a short wavelength-sensitive and a middle/long wavelength-sensitive opsin (S- and M-opsin), forming opposing, overlapping gradients along the dorsal-ventral axis. Here, we analyzed the distribution of all cone types across the entire retina for two commonly used mouse strains. We found, unexpectedly, that 'true S-cones' (S-opsin only) are highly concentrated (up to 30% of cones) in ventral retina. Moreover, S-cone bipolar cells (SCBCs) are also skewed towards ventral retina, with wiring patterns matching the distribution of true S-cones. In addition, true S-cones in the ventral retina form clusters, which may augment synaptic input to SCBCs. Such a unique true S-cone and SCBC connecting pattern forms a basis for mouse color vision, likely reflecting evolutionary adaptation to enhance color coding for the upper visual field suitable for mice's habitat and behavior.
颜色是生存的重要视觉线索，通过比较具有不同光谱敏感性的光感受器信号来编码。鼠视网膜表达短波长敏感和中/长波长敏感视蛋白（S-和 M-视蛋白），沿背腹轴形成相反的重叠梯度。在这里，我们分析了两种常用小鼠品系整个视网膜中所有视锥细胞类型的分布。出乎意料的是，我们发现“真正的 S 锥细胞”（仅 S-视蛋白）在腹侧视网膜中高度集中（高达 30%的视锥细胞）。此外，S 锥体细胞双极细胞（SCBC）也偏向腹侧视网膜，其布线模式与真正 S 锥细胞的分布相匹配。此外，腹侧视网膜中的真正 S 锥细胞形成簇，这可能会增加对 SCBC 的突触输入。这种独特的真正 S 锥细胞和 SCBC 连接模式为小鼠的颜色视觉形成了基础，可能反映了进化适应，以增强适合小鼠栖息地和行为的上视野的颜色编码。
