Lateral hypothalamic relations with medial hypothalamus and limbic areas in geese.

Spontaneous unit activity was recorded in the posteromedial hypothalamic (PMH) and preventricular magnocellular (PVM) nuclei, septal area (S) and hippocampal formation (Hp). Modifications of cellular firing induced by lateral hypothalamic area (LHA) stimulation were examined. Both thiopental anaesthetized and chronic non anaesthetized geese were used. Thiopental appeared to significantly decrease the spontaneous discharge frequency of PMH neurons, and to block both orthodromic and antidromic activations elicited by LHA stimulation. The results indicated that LHA has a predominantly inhibitory influence on PMH as well as on PVM and septal area. The study of antidromic evoked responses in the four areas investigated (PMH, PVM, S, Hp) demonstrated that these structures in turn exert a feed-back control onto LHA. These results are compared with previous electrophysiological, anatomical and behavioral feeding data and an attempt is made to establish some comparisons between birds and mammals.