Alterations in preoptic unit activity on stimulation of caudal brain stem EEG-synchronizing structures

Abstract

Effects of stimulation of EEG-synchronizing structures of the caudal brain stem reticular formation with low (6 Hz) and high (100 Hz) frequencies were studied on 42 neurons of the preoptic area, in encephale isole cats. Though low-frequency stimulation produced excitation and inhibition, the majority of the influenced neurons of the preoptic area had effects of the former type. Cortical EEG synchronization was also induced by low-frequency stimulation of the caudal brain stem. High-frequency stimulation, on the other hand, produced inhibition in a majority of the influenced neurons and induced, mostly, desynchronization of the cortical EEG. A majority of the neurons that were inhibited on high-frequency stimulation, remained unaffected during low-frequency stimulation. The influence induced on the preoptic area neurons by low-frequency stimulation could be obtained even in the absence of cortical EEG synchronization. Changes induced on preoptic neurons by high-frequency stimulation may be partially related to induced cortical EEG desynchronization.