Kaladchibachi Sevag, Negelspach David C, Fernandez Fabian
Department of Psychology, University of Arizona, Tucson, AZ 85724, USA.
Department of Neurology, University of Arizona, Tucson, AZ 85724, USA.
Clocks Sleep. 2018 Sep 27;1(1):26-41. doi: 10.3390/clockssleep1010004. eCollection 2019 Mar.
The circadian clock is comprised of two oscillators that independently track sunset (evening) and sunrise (morning), though little is known about how light responses differ in each. Here, we quantified the morning oscillator's responses to 19 separate pulse trains, collecting observations from over 1300 at ZT23. Our results show that the advances in activity onset produced by these protocols depended on the tempo of light administration even when total exposure was conserved across a 15-min window. Moreover, patterns of stimulation previously shown to optimize the evening oscillator's delay resetting at ZT13 (an hour after dusk) were equally effective for the M oscillator at ZT23 (an hour before dawn), though the morning oscillator was by comparison more photosensitive and could benefit from a greater number of fractionation strategies that better converted light into phase-shifting drive. These data continue to build the case that the reading frames for the pacemaker's time-of-day estimates at dusk and dawn are not uniform and suggest that the "photologic" for the evening versus morning oscillator's resetting might be dissociable.
昼夜节律钟由两个振荡器组成，它们分别独立追踪日落（傍晚）和日出（早晨），不过对于每个振荡器的光反应差异了解甚少。在此，我们量化了早晨振荡器对19种不同脉冲序列的反应，在ZT23收集了超过1300次的观测数据。我们的结果表明，即使在15分钟的窗口内总曝光量保持不变，这些方案所产生的活动开始时间提前也取决于光照给药的节奏。此外，先前显示能在ZT13（黄昏后一小时）优化傍晚振荡器延迟重置的刺激模式，在ZT23（黎明前一小时）对M振荡器同样有效，不过相比之下早晨振荡器对光更敏感，并且可以从更多能更好地将光转化为相移驱动的分割策略中受益。这些数据继续证明，起搏器在黄昏和黎明时估计一天时间的读码框并不一致，并表明傍晚与早晨振荡器重置的“光逻辑”可能是可分离的。
