Pohl H
Comp Biochem Physiol B. 1983;76(4):723-9. doi: 10.1016/0305-0491(83)90384-x.
Circadian rhythms of wheel-running activity of the antelope ground squirrel (Ammospermophilus leucurus) were entrained by light-dark cycles (LD: 100 1x vs total darkness) with periods (T) between ca 23.75 and 24.75 hr. Two 1-hr light pulses per cycle ('skeleton photoperiods') with T = 24.25 hr as well as one 1-hr light pulse per cycle with Ts of 23.75 and 24.25 hr were effective in entraining the circadian activity rhythms in at least 50% of the antelope ground squirrels. Phase and period responses to single 1-hr light pulses were measured which depend on the initial phase and period of the rhythm. It is concluded that discrete (phasic) light input contributes to the mechanism of entrainment to LD cycles in diurnal rodents.
羚羊地松鼠（Ammospermophilus leucurus）的转轮活动昼夜节律被明暗周期（LD：100勒克斯与完全黑暗）所调节，周期（T）在约23.75至24.75小时之间。每个周期两个1小时的光脉冲（“骨架光周期”），T = 24.25小时，以及每个周期一个1小时的光脉冲，T分别为23.75和24.25小时，在至少50%的羚羊地松鼠中有效地调节了昼夜活动节律。测量了对单个1小时光脉冲的相位和周期反应，这些反应取决于节律的初始相位和周期。得出的结论是，离散（阶段性）光输入有助于昼行性啮齿动物对LD周期的调节机制。
