A further study of the inhibitory processes induced by the activation of the preoptic hypnogenic structure.

Abstract

Stimulation of the basal preoptic area in the encephale isole cat did not impair the transmission of corticopetal impulses through the lateral geniculate nucleus. The finding of Bonnet and Briot is confirmed that the response of the visual cortex evoked by a geniculate pulse is regularly followed by an activation of the mesencephalic reticular formation, mediated by corticofugal impulses. This reticular response has been found to be strongly inhibited by a conditioning preoptic stimulation. Unilateral high frequency low voltage stimulation of the basal preoptic area, in the encephale isole preparation, evoked a bilateral ocular hypnic syndrome unaccompanied by electrocortical manifestations of sleep. The stereotaxic location of the stimulating electrodes for the production of this ocular syndrome was the same as the one required for induction of sleep, for diffuse cortical synchronisation and for the inhibition of the activating reticular system.