Optogenetic dissection of sleep-wake circuits in the brain

Abstract

The use of optogenetics has increased markedly in recent years and is becoming a popular tool to determine the role of various circuits in behaviour, as well as identifying the neuronal components of those circuits. The lateral hypothalamus and its projections have been studied extensively with respect to sleep-wake behaviour using optogenetics. The hypocretin system has been found to be a powerful wake promoting region which recruits the noradrenergic locus coeruleus to evoke it's effects. A subset of neurones in the lateral hypothalamus producing melanin concentrating hormone (MCH) have been shown to promote REM sleep. The projections from the lateral hypothalamus are diverse, as are it's functions in other behaviours such as energy homeostasis and feeding. Future work is now needed to determine which part of this circuitry is required for regulation of the sleep-wake state and ultimately how consciousness is controlled.