[Regulation of sleep and wakefulness through the monoaminergic and cholinergic systems].

Sleep and wakefulness are regulated in the brainstem and hypothalamus. Classical brain dissecting or stimulating studies have proposed the concept of an ascending reticular activating system, presently known as the wakefulness center, located in the caudal midbrain/rostral pontine (mesopontine) areas, comprising the serotonergic, noradrenergic and cholinergic neural populations. These neural groups, in association with the histaminergic and orexinergic neurons in the hypothalamus, activate the cerebral the cortex through the thalamus or basal forebrain. This activating (waking) system is controlled by the slow wave sleep (SWS) generating system in the preoptic area, which receives inhibitory signals from the waking center. The mesopontine area is also involved in the regulation of rapid eye movement (REM) sleep. Reciprocal interactions between the cholinergic/glutamatergic excitatory systems and the aminergic/GABAergic inhibitory systems are crucial for the regulation of REM sleep. In the REM activating system, mutual excitatory interactions between cholinergic and glutamatergic neurons serve to maintain the state of REM sleep. The REM activating system in the mesopontine area receives GABAergic inhibitory signals from several neural groups in the periaqueductal gray and the medulla. Thus, sleep and wakefulness are controlled by the interplay of various neural populations located in several areas in the central nervous system.