Dacey D M, Lee B B
Department of Biological Structure, University of Washington, Seattle 98195.
Nature. 1994 Feb 24;367(6465):731-5. doi: 10.1038/367731a0.
Colour vision in humans and Old World monkeys begins with the differential activation of three types of cone photoreceptor which are maximally sensitive to short (S), medium (M) and long (L) wavelengths. Signals from the three cone types are relayed to the retinal ganglion cells via cone-specific bipolar cell types. Colour-coding ganglion cells fall into two major physiological classes: the red-green opponent cells, which receive antagonistic input from M- and L-sensitive cones, and the blue-yellow opponent cells, which receive input from S-sensitive cones, opposed by combined M- and L-cone input. The neural mechanisms producing colour opponency are not understood. It has been assumed that both kinds of opponent signals are transmitted to the lateral geniculate nucleus by one type of ganglion cell, the midget cell. We now report that a distinct non-midget ganglion cell type, the small bistratified cell, corresponds to the physiological type that receives excitatory input from S cones, the 'blue-on' cell. Our results thus demonstrate an anatomically distinct pathway that conveys S-cone signals to the brain. The morphology of the blue-on cell also suggests a novel hypothesis for the retinal circuitry underlying the blue-yellow opponent response.
人类和旧世界猴的色觉始于三种视锥光感受器的差异激活，这三种视锥光感受器分别对短（S）、中（M）和长（L）波长最为敏感。来自这三种视锥类型的信号通过特定视锥的双极细胞类型传递到视网膜神经节细胞。颜色编码神经节细胞分为两个主要的生理类别：红-绿拮抗细胞，它接收来自M型和L型敏感视锥的拮抗输入；蓝-黄拮抗细胞，它接收来自S型敏感视锥的输入，并受到M型和L型视锥联合输入的拮抗。产生颜色拮抗的神经机制尚不清楚。人们一直认为，这两种拮抗信号都由一种神经节细胞——侏儒细胞——传递到外侧膝状体核。我们现在报告，一种不同的非侏儒神经节细胞类型——小双分层细胞——对应于从S视锥接收兴奋性输入的生理类型，即“蓝敏”细胞。因此，我们的结果证明了一条从解剖学上看不同的将S视锥信号传递到大脑的通路。蓝敏细胞的形态也为蓝-黄拮抗反应背后的视网膜回路提出了一个新的假说。
