Powers M K, Bassi C J, Raymond P A
Department of Psychology, Vanderbilt University, Nashville, TN 37240.
Invest Ophthalmol Vis Sci. 1988 Jan;29(1):37-43.
Goldfish (Carassius auratus) were reared from hatching in constant light (340 lux), cyclic light (12 hr 320 lux, 12 hr dark) or constant dark. Absolute visual threshold was determined psychophysically in animals that still responded to visual stimuli after 1-3 years of exposure, by means of a classically conditioned respiration suppression technique wherein animals were presented with different intensities of large diffuse flashes of monochromatic light. Fish reared in constant light and fish reared in cyclic light responded reliably to stimuli above threshold, but fish reared in constant light were on average 0.58 log unit less sensitive at 532 nm, near the peak of the rod action spectrum. Two of the four fish reared in darkness did not respond to the stimuli, and thus could not be conditioned, and another fish reared in darkness responded only occasionally; threshold could not be measured in these three fish. The one fish reared in darkness that responded consistently enough to be conditioned was more than 5 log units less sensitive than normally reared fish on the first day of testing, and became progressively less sensitive over the next 2 days. Rearing under constant dark or constant light had no obvious effect on spectral sensitivity at absolute threshold. The effect of rearing in constant light on absolute threshold correlates with morphological changes in rod density, but the effect of rearing in constant darkness does not.
金鱼（Carassius auratus）从孵化起就饲养在持续光照（340勒克斯）、循环光照（12小时320勒克斯，12小时黑暗）或持续黑暗环境中。通过经典条件反射呼吸抑制技术，对暴露1至3年后仍对视觉刺激有反应的动物进行心理物理学测定绝对视觉阈值，该技术是向动物呈现不同强度的单色光大型漫射闪光。饲养在持续光照下的金鱼和饲养在循环光照下的金鱼对阈值以上的刺激有可靠反应，但饲养在持续光照下的金鱼在532纳米处（接近视杆细胞作用光谱峰值）平均敏感度低0.58对数单位。饲养在黑暗中的四条金鱼中有两条对刺激无反应，因此无法进行条件反射训练，另一条饲养在黑暗中的金鱼只是偶尔有反应；这三条金鱼无法测量阈值。饲养在黑暗中的一条金鱼反应足够一致，可以进行条件反射训练，在测试的第一天，其敏感度比正常饲养的金鱼低5个多对数单位，在接下来的两天里敏感度逐渐降低。在持续黑暗或持续光照下饲养对绝对阈值时的光谱敏感度没有明显影响。在持续光照下饲养对绝对阈值的影响与视杆细胞密度的形态变化相关，但在持续黑暗中饲养的影响则不然。
