A cerebellar inhibitory signal for the regulation of sleep-wakefulness cycle
会议名称：《中国睡眠研究会第十一届全国学术年会》
会议日期：2019年
关 键 词：Deep cerebellar nuclei Ventral lateral thalamus Purkinje cell Sleep Wakefulness Multiple units recording Optogenetics Chemogenetics
摘 要：The cerebellum is a critical component of the CSN, involved in motor control and motor learning. However, patients suffering from cerebellar disorders induce not only motor deficits, but also non-motor symptoms such as increased daytime sleepiness. Vice versa, patients suffering primary sleep disorders such as daytime sleepiness are often accompanied by a decreased cerebellar volume. These data support the notion that the cerebellum might be involved in regulating sleep and wakefulness. Nevertheless, the neural mechanisms underlying this involvement remain largely unclear. Here, we examined a genetically tractable population of neurons in the mouse deep cerebellar nuclei（DCN）, whose axon fibers specifically project to the ventral lateral thalamus（VL）. We show that these neurons are composed of GABAergic（～50%）, Glycinergic（～25%） and Glutamatergic（～25%） neurons in the DCN. Therefore, most of the VL-projected DCN neurons are inhibitory units. Intriguingly, the inhibitory VL-projected DCN neurons also recurrently innervate in the cerebellar cortex. Immnohistochemmical staining reveal that the nucleocortical fiber terminals formed filopodia-like protrusions in the vicinity of Purkinje cell（PC） layer in the cerebellar cortex, indicating these fibers preferentially target the PCs. Indeed, optogenetic inhibition of the VL-projected DCN neurons disinhibits the PCs in the cerebellar cortex, which thereafter cause widespread inhibition in the DCN. Vice versa, optogenetic stimulation of the VL-projected DCN neurons induces rapid inhibition of the PCs, which results in widespread excitation in the DCN. It turns out that the inhibitory VL-projected DCN neurons can bi-directionally modulate the activities of PCs in the cerebellar cortex. In contrast, optogenetic activation of VL/VM-projected glutamatergic DCN neurons fails to induce widespread excitation in the DCN. Moreover, optogenetic activation of the VL-projected DCN neurons can provide an internal amplification of the outputs from the cerebellar cortex, as evidenced by the increased associative memory. Furthermore, by combining optogenetics and multiple units recording techniques, we tagged the VL-projected DCN neurons in vivo, and show that they exhibit firing activity change preceding the sleep-wakefulness transition. On average, the VL-projected DCN neurons increase their firing rates 1-2 sec before the transition from NREM sleep to wakefulness state. Likewise, these neurons exhibit increased firing rates 1-2 sec before the transition from REM sleep to wakefulness state. In contrast, the VL-projected DCN neurons decrease their firing 1-2 sec before the transition from wakefulness to NREM sleep. To further determine the role of VL-projected DCN neurons in the regulation of sleep-wakefulness transition, we used CNO to chemically trigger the change of firing activity in the VL-projected DCN neurons. It shows that chemogenetic inhibition of the VL-projected DCN neurons result in increased wakefulness and r