Rosenwasser A M, Dwyer S M
Department of Psychology, University of Maine, Orono, ME 04469-5742, USA.
Physiol Behav. 2001 May;73(1-2):175-83. doi: 10.1016/s0031-9384(01)00466-8.
A variety of photic and nonphotic stimuli can phase-shift the mammalian circadian pacemaker. It has been suggested that the phase-response curves (PRCs) characterizing these diverse stimuli may comprise two major PRC families, one typified by the photic PRC describing the response to brief light pulses, and the other typified by the nonphotic PRC describing the response to stimuli evoking behavioral arousal and/or locomotor activity. Additionally, the mammalian circadian pacemaker can be phase-shifted by dark pulses presented on a constant-light (LL) background. While dark pulse-induced phase shifting was interpreted originally as a mirror-image photic effect, other observations suggest that the dark pulse PRC may instead belong to the family of nonphotic, activity-dependent PRCs. In a recent study, we reexamined the phase-shifting effects of dark pulses in the Syrian hamster, and concluded that the dark pulse PRC reflects both nonphotic and photic mirror-image mechanisms. In the current report, we reanalyze previously published hamster PRC data using polynomial curve-fitting procedures. The results of these analyses reveal that (a) the photic and nonphotic PRCs have identical shape but opposite phasing, and (b) the dark pulse PRC can be modeled by simple summation of nonphotic and photic mirror-image PRCs. This model predicts accurately the shape of the dark pulse PRC, particularly the extension of the phase-advance region into the subjective night.
多种光刺激和非光刺激能够使哺乳动物的昼夜节律起搏器发生相位偏移。有人提出，表征这些不同刺激的相位响应曲线（PRC）可能包含两个主要的PRC家族，一个以描述对短暂光脉冲响应的光PRC为代表，另一个以描述对引发行为唤醒和/或运动活动的刺激响应的非光PRC为代表。此外，哺乳动物的昼夜节律起搏器可被置于持续光照（LL）背景下的暗脉冲所相位偏移。虽然暗脉冲诱导的相位偏移最初被解释为镜像光效应，但其他观察结果表明，暗脉冲PRC可能反而属于非光的、与活动相关的PRC家族。在最近的一项研究中，我们重新审视了叙利亚仓鼠中暗脉冲的相位偏移效应，并得出结论，暗脉冲PRC反映了非光和光镜像机制。在本报告中，我们使用多项式曲线拟合程序重新分析了先前发表的仓鼠PRC数据。这些分析结果表明：（a）光PRC和非光PRC形状相同但相位相反；（b）暗脉冲PRC可以通过非光和光镜像PRC的简单相加来建模。该模型准确预测了暗脉冲PRC的形状，特别是相位提前区域延伸到主观夜间的情况。
