Schwartz E A
J Physiol. 1975 Apr;246(3):639-51. doi: 10.1113/jphysiol.1975.sp010908.
The intracellular responses of rods in the retina of the turtle, Chelydra serpentina, were studied with brief flashes of monochromatic light. 1. Flashes of red or green light applied over an area 25 mum in diameter produce responses with the same shape. With such restricted stimuli, the spectral sensitivity of a rod agrees well with the absorption spectrum of the porphyropsin pigment contained in its outer segment. 2. With stimulating spots more than 500 mum in diameter, dim flashes of red or green light produce responses having different shapes. When the spectral sensitivity of a rod is tested using dim lights of large diameter, the sensitivity to red light is much greater than predicted by the absorption spectrum of porphyropsin. 3. The shape of the response produced by large diameter spots of dim, red light resembles that of cones. 4. Increasing the diameter of a dim, red spot beyond 500 mum markedly alters the amplitude and shape of responses from horizontal cells but does not significantly affect the response of rods. It is concluded that rods receive an excitation from neighbouring cones. This interaction is unlikely to be mediated by type I luminosity horizontal cells but may be mediated by either direct connexions between cones and rods or by an interneurone with a small receptive field.
利用单色光的短暂闪光，对蛇鳄龟视网膜中视杆细胞的细胞内反应进行了研究。1. 在直径25微米的区域上施加红色或绿色光闪光，会产生形状相同的反应。对于这种受限刺激，视杆细胞的光谱敏感性与其外段所含视紫质色素的吸收光谱非常吻合。2. 对于直径超过500微米的刺激光斑，红色或绿色光的暗光闪光会产生形状不同的反应。当使用大直径暗光测试视杆细胞的光谱敏感性时，对红光的敏感性远高于视紫质吸收光谱所预测的。3. 由大直径的暗红色光斑产生的反应形状类似于视锥细胞的反应形状。4. 将暗红色光斑的直径增加到500微米以上，会显著改变水平细胞反应的幅度和形状，但对视杆细胞的反应没有显著影响。得出的结论是，视杆细胞从相邻视锥细胞接收兴奋。这种相互作用不太可能由I型亮度水平细胞介导，但可能由视锥细胞和视杆细胞之间的直接连接或具有小感受野的中间神经元介导。
