The superior colliculus–pretectum mediates the direct effects of light on sleep

Light and dark have immediate effects on sleep and wakefulness in mammals, but the neural mechanisms underlying these effects are poorly understood. Lesions of the visual cortex or the superior colliculus–pretectal area were performed in albino rats to determine retinorecipient areas that mediate the effects of light on behavior, including rapid eye movement sleep triggering by lights-off and redistribution of non-rapid eye movement sleep in short light–dark cycles. Acute responses to changes in light conditions were virtually eliminated by superior colliculus-pretectal area lesions but not by visual cortex lesions. Circadian entrainment was evident in both groups with lesions and in normal controls. Thus, acute light-dark effects on sleep and wakefulness appear to be mediated independently from cortical vision or circadian rhythms.

光照与黑暗对哺乳动物的睡眠-觉醒状态具有即时调控效应，但其背后的神经机制仍未得到充分阐明。本研究通过对白化大鼠实施视觉皮层（visual cortex）或上丘-顶盖前区（superior colliculus–pretectal area）损伤手术，旨在明确介导光照对行为产生影响的视网膜接收脑区（retinorecipient areas），其中包括熄灯触发快速眼动睡眠（rapid eye movement sleep）以及在短明暗周期中重新分布非快速眼动睡眠（non-rapid eye movement sleep）的相关通路。上丘-顶盖前区损伤可完全消除机体对光照条件变化的急性响应，而视觉皮层损伤则无此效果。在两组损伤大鼠与正常对照组中，均观察到明显的昼夜节律同步化（circadian entrainment）现象。由此可见，光照-黑暗对睡眠与觉醒的急性调控效应，似乎独立于皮层视觉通路或昼夜节律系统发挥作用。