title: Central mechanisms of paradoxical sleep.
abstract: Paradoxical sleep (PS) is composed of several characteristic "tonic" and "phasic" events. In this paper, it was shown that each of these "PS-subsystems" might be generated by distinct brainstem neuron groups and involved in the cholinergic, cholinoceptive, and monoaminoceptive mechanisms. In addition, it was suggested that the central mechanisms of PS consist of: cholinergic PS-on neurons that discharge tonically and specifically during the periods of PS; and monoaminergic (serotonergic, noradrenergic, and presumably also adrenergic) PS-off neurons that cease firing selectively during this period of sleep. The PS-on neurons play an executive role, while the PS-off ones play a permissive role in the generation of PS. The PS-on neurons are located both in the mediodorsal pontine tegmentum, especially the peri-LC alpha and medial part of the LC alpha, and in the ventromedial medulla, particularly the Mc. The PS-off neurons are located rather diffusely in the lower brainstem. There exist both excitatory interactions between the PS-on neurons, between the PS-off neurons and reciprocal inhibitory interactions between the PS-on and PS-off neurons. Periodically, these interactions lead to, by still unknown mechanisms, the excitation of all PS-on neurons and inhibition of all PS-off neurons, and, consequently, the appearance of PS.
mesh_terms: D002799:Cholinergic Fibers / Q000502:physiology; D003344:Cortical Synchronization; D006801:Humans; D008526:Medulla Oblongata / Q000502:physiology*; D008959:Models, Neurological; D009129:Muscle Tonus; D009638:Norepinephrine / Q000502:physiology; D011187:Posture; D012895:Sleep, REM / Q000502:physiology*; D013681:Tegmentum Mesencephali / Q000502:physiology*
chemical_list: D009638:Norepinephrine