Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland.
Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland.
Curr Biol. 2018 Feb 5;28(3):392-400.e3. doi: 10.1016/j.cub.2017.12.049. Epub 2018 Jan 18.
During wakefulness, pupil diameter can reflect changes in attention, vigilance, and cortical states. How pupil size relates to cortical activity during sleep, however, remains unknown. Pupillometry during natural sleep is inherently challenging since the eyelids are usually closed. Here, we present a novel head-fixed sleep paradigm in combination with infrared back-illumination pupillometry (iBip) allowing robust tracking of pupil diameter in sleeping mice. We found that pupil size can be used as a reliable indicator of sleep states and that cortical activity becomes tightly coupled to pupil size fluctuations during non-rapid eye movement (NREM) sleep. Pharmacological blocking experiments indicate that the observed pupil size changes during sleep are mediated via the parasympathetic system. We furthermore found that constrictions of the pupil during NREM episodes might play a protective role for stability of sleep depth. These findings reveal a fundamental relationship between cortical activity and pupil size, which has so far been hidden behind closed eyelids.
在清醒状态下，瞳孔直径可以反映注意力、警觉性和皮质状态的变化。然而，在睡眠期间，瞳孔大小与皮质活动的关系尚不清楚。由于眼睑通常闭合，因此在自然睡眠期间进行瞳孔测量具有内在的挑战性。在这里，我们提出了一种新的头部固定睡眠范式，结合红外反向照明瞳孔测量法（iBip），可在睡眠中的小鼠中可靠地跟踪瞳孔直径。我们发现，瞳孔大小可用作睡眠状态的可靠指标，并且在非快速眼动（NREM）睡眠期间，皮质活动与瞳孔大小波动紧密耦合。药理阻断实验表明，睡眠期间观察到的瞳孔大小变化是通过副交感神经系统介导的。我们还发现，NREM 发作期间瞳孔收缩可能对睡眠深度的稳定性起到保护作用。这些发现揭示了皮质活动和瞳孔大小之间的基本关系，而这种关系迄今为止一直被紧闭的眼皮所掩盖。
