[The direct activating influence of the lateral hypothalamic preoptic area on the thalamic synchronizing system]

In order to reveal the mechanisms of participation of the preoptic hypothalamic area in sleep-wake cycle regulation the effects of its electrical stimulation on activity of the thalamic median center were studied in chronic experiments in cats. Ipsi- and contralateral projections from the lateral preoptic area to the thalamic median center were electrophysiologically demonstrated. Activatory influence of the preoptic area was shown on the thalamic mechanisms of spindle activity generation. The obtained data suggest the interaction of the preoptic area with the structures of non-specific thalamus via the direct pathways to be one of the mechanisms of the preoptic area participation in sleep initiation and formation of the slow-wave sleep.