Le bâillement, du réflexe à la pathologie
EEG correlats of yawning during sleep onset JV Laing & RD Ogilvie


Why we sleep : the evolutionary pathway to the mammalian sleep
MC. Nicolau, M. Akaarir, A. Gamundi, J. Gonzalez, RV. Rial
Legendre, R. et Pieron, H. (1912) De la propriété hypnotoxique des humeurs développées au cours d'une veille prolongée C.R. Soc. Biol. (Paris), 72: 210-212.

mise à jour 8 août 2002
Nature Reviews Neuroscience
The neurobiology of sleep: genetics, cellular physiology and subcortical networks
Edward F. Pace-Schott and J. Allan Hobson
Laboratory of Neurophysiology, Department of Psychiatry, Harvard Medical School, Massachusetts Mental Health Center, 74 Fenwood Road,Boston,
Massachusetts 02115, USA
The cognitive neuroscience of sleep: neuronal systems, consciousness and learning J Allan Hobson et EF Pace-Schott sur le site Nature Reviews Neuroscience
Hypothalamic integration of central and peripheral clocks Buijs RM
Phylogenetic data bearing on the REM sleep learning connection JM Siegel
Abstract : To appreciate the neural underpinnings of sleep, it is important to view this universal mammalian behaviour at multiple levels of its biological organization. Molecularly, the circadian rhythm of sleep involves interlocking positive- and negative-feedback mechanisms of circadian genes and their protein products in cells of the suprachiasmatic nucleus that are entrained to ambient conditions by light. Circadian information is integrated with information on homeostatic sleep need in nuclei of the anterior hypothalamus. These nuclei interact with arousal systems in the posterior hypothalamus, basal forebrain and brainstem to control sleep onset. During sleep, an ultradian oscillator in the mesopontine junction controls the regular alternation of rapid eye movement (REM) and non-REM sleep. Sleep cycles are accompanied by neuromodulatory influences on forebrain structures that influence behaviour, consciousness and cognition. [...]
Over the past decade, a remarkable explosion of new findings has allowed us to construct a much more complete picture of the genetic mechanisms, cellular neurophysiology and subcortical networks that underlie the neurobiology of sleep. This explosion has been made possible by technological advances in molecular biology and biotechnology (such as gene cloning and DNA sequencing), as well as in cellular neurophysiology (such as sophisticated combinations of microdialysis, unit recording, axonal tracers and immunohistochemistry). We now know that an interlocking positive - negative feedback mechanism that controls gene transcription in individual cells of the SCN of the hypothalamus is the molecular basis of circadian rhythmicity in mammals. This endogenous periodicity can be entrained to the ambient photoperiod by photons that impinge on the circadian photopigment,melanopsin, in RGCs, which convey this information to the SCN monosynaptically through the RHT. Circadian rhythmicity emerges from SCN cells by action potentials that impinge on adjacent nuclei of the anterior hypothalamus, including the PVH, SPZ and DMH; in turn, these nuclei convey circadian rhythmicity to structures that control rhythmic physiological processes, such as sleep, temperature and endocrine output. Feedback to the SCN circadian oscillator can occur through melatonin from the pineal gland, which reliably secretes this sleep-related hormone in response to polysynaptically conveyed signals from the SCN. A key hypothalamic structure that receives circadian output from the SCN through the SPZ and the DMH is the VLPO, which promotes NREM sleep. The VLPO might initiate sleep onset through reciprocal inhibition of cholinergic, noradrenergic and serotonergic arousal systems in the brainstem, as well as histaminergic systems of the posterior hypothalamus and cholinergic systems of the basal forebrain, all of which are modulated by the orexinergic arousal system of the lateral hypothalamus. These arousal systems conspire to promote the activated brain states of waking,whereas the cholinergic system acts alone to promote the activated state of REM sleep.
brain regions