Abstract
While the functions of sleep are still a matter of debate and may include memory consolidation and plasticity, the neural substrates of sleep and wake states are the subject of intense study. Successive sleep-wake cycles rely on an appropriate balance between sleep-promoting nuclei of the brain located in the anterior hypothalamus and, arousal-promoting nuclei from the posterior hypothalamus and the brainstem including the dopamine, norepinephrine, serotonin systems. We have investigated some of the neural substrates of arousal and REM sleep using a combination of electrophysiology and optogenetics in freely-moving mice. We recently demonstrated that a subset of hypothalamic cells expressing the peptide melanin-concentrating hormone (MCH) are both sufficient for the induction of rapid-eye movement (REM) sleep (or paradoxical sleep), and required for theta rhythm stability during REM sleep. We further identified a subset of inhibitory cells from the same hypothalamus area that directly control the activity of the reticular thalamus nuclei and induce arousal through feed-forward disinhibition of thalami-cortical loop during NREM, but not REM sleep. This lecture will present these recent work and proposed an integrated model of hypothalamic regulation of sleep-wake states, as well as consciousness.