Two separate synchronizing mechanisms in the basal forebrain: study of the synchronizing effects of the rostral hypothalamus, preoptic region and olfactory tubercle
Benedek, G.; Obál, F.; Szekeres, L.; Obál, F.
Archives Italiennes de Biologie 117(2): 164-185
1979
ISSN/ISBN: 0003-9829 PMID: 315219 Document Number: 150497
Systematic mapping of the region between the rostral hypothalamus and the olfactory tubercle in the rat by low and high frequency stimulations revealed a dorsal and a ventral synchronizing area having diverse functional characteristics. The ventral region included the laterobasal preoptic area and the cortical part of the olfactory tubercle. Although differences were found in the type of synchronization elicited by low frequency stimulation of the 2 areas, the cortical and hippocampal synchronizing effect of high frequency stimulation showed a common feature. The dorsal region extended from the lateral hypothalamus through the dorsal preoptic area to the olfactory tubercle. Its characteristics were similar to those of the nonspecific thalamic system, i.e., low frequency stimulations resulted in recruiting type cortical synchronization, while high frequency stimulations desynchronized cortical and hippocampal activity. The regions near the midline were of a powerful desynchronizing nature. High frequency stimulation resulted in cortical desynchronization and hippocampal .theta. activity and sometimes cortical desynchronization was induced by low frequency stimulation. This activity was accompanied by high voltage hippocampal synchronization. Direct cortical pathways to the ventral synchronizing area and the participation of the thalamlus in producing the synchronizing effect of the dorsal area are the cause of the diverse activities associated with these 2 regions. Pathways from the dorsal area to the brain stem reticular formation may be responsible for the desynchronization obtained by high frequency stimulation of the dorsal area.