Ruis J F, Rietveld W J, Buys J P
Department of Physiology, University of Leiden, The Netherlands.
Physiol Behav. 1991 Dec;50(6):1233-9. doi: 10.1016/0031-9384(91)90588-f.
Wistar rats were exposed to 24-h cycles of sinusoidal varying light intensity at various amplitudes (A) and mean intensity (I) levels. The cycle minimum was at least 0.1 lux. Food approaches and wheel running activity were continuously recorded. Entrainment was observed to light cycles with amplitudes as low as 2 lux. The success of entrainment increased with A and decreased with I, and loss of entrainment was accompanied by relative coordination. In a separate experiment, we measured the freerunning period (tau) in constant light at various I levels. The tau-illuminance curve was pseudolinear at low I (above 0.1 lux) and saturated at high I (above 100 lux). The intensity dependence of tau corresponded to the intensity response characteristics of light responsive cells in the rat suprachiasmatic nuclei, as published by other authors. It was hypothesized that the light responsive cells mediate the parametric effects of constant light and of sine waves of light.
将Wistar大鼠暴露于不同振幅（A）和平均强度（I）水平的24小时正弦变化光强度周期中。周期最小值至少为0.1勒克斯。持续记录食物接近和转轮活动情况。观察到振幅低至2勒克斯的光周期也能产生同步化。同步化的成功率随A增加而增加，随I降低而降低，同步化丧失伴随着相对协调性。在另一个实验中，我们在不同I水平的恒定光照下测量了自由运行周期（tau）。tau-照度曲线在低I（高于0.1勒克斯）时呈伪线性，在高I（高于100勒克斯）时饱和。tau的强度依赖性与其他作者发表的大鼠视交叉上核中光反应细胞的强度反应特征相对应。据推测，光反应细胞介导了恒定光和正弦波光的参数效应。
