Topographical differences in the responses of single hypothalamic neurons to limbic stimulation

Abstract

Extracellularly recorded action potentials from single neurons in the tuberal and adjacent lateral hypothalamus were studied in cats bymeansof computer summation; both spontaneous firing and responses to electrical stimulation in certain limbic structures were examined. The ventromedical hypothalamic region is a prime recipient for both the amygdaloid and septal projection systems, although responses to stimulation of these regions were also found in the dorsal and lateral hypothalamic regions. In contrast impulses arising in the midbrain tegmentum project chiefly to the dorsal and lateral hypothalamic regions. Both excitatory and inhibitory responses were observed in all hypothalamic regions studied. Differences in spontaneous firing characteristics were observed between lateral hypothalamic neurons and those located more medially, in terms of both frequency of firing and inter spike-interval distribution.