Nos différents cerveaux au cours du sommeil

While the different stages of sleep have long been considered as being relatively homogeneous, the use of functional neuroimaging and high resolution EEG and MEG in fact reveal states in which different cerebral regions undergo functional reorganisation. The purpose of this review is to show the contribution of such methods of topographical analysis of cerebral activity during different states of wakefulness and sleep. Slow wave sleep is characterised by frontal and thalamic deactivation and during the early phase of NREM sleep deactivation of mainly thalamocortical connectivity. In REM sleep, frontal deactivation is also present, but in this case associated with activation of limbic structures and posterior cortex. This topographical variation depends on the activity during the waking period prior to sleep onset and the subject's age (the degree of topographical heterogeneity seeming to increase with age). These data shed new light on certain sleep disorders such as insomnia.