Individual differences in effects of hypothalamic stimulation: The role of stimulation locus

Several loci in the dorsal-ventral plane of the lateral hypothalamic area (LHA) were stimulated in each of 14 animals to determine the location of positive and negative sites for stimulation-induced eating and drinking, and possible explanations for the facts that the same stimulation has different effects on different animals.

Abstract

Several loci in the dorsal-ventral plane of the lateral hypothalamic area (LHA) were stimulated in each of 14 animals to determine the location of positive and negative sites for stimulation-induced eating and drinking. In six animals positive sites were found at 18 mm intervals in an area between the ventral aspect of the zona incerta and a level about 12 mm above the base of the brain; all negative sites in these animals were found to lie outside of this area. Within this area electrode movements produced only small changes in threshold, while at the boundaries of this area 18 mm changes in electrode locus could produce drastic threshold changes. In the remaining eight animals stimulation never induced eating or drinking even though the entire depth of the LHA was explored. These results are discussed in terms of possible explanations for the facts that: (a) the same stimulation has different effects on different animals; and, (b) the same stimulation has different effects on the same animal at different times.