Preference for mode of obtaining reinforcement in rats with lesions in septal or ventromedial hypothalamic area.

Abstract

Assigned 54 female Holtzman albino rats to groups receiving sham operations, septal lesions, or ventromedial hypothalamic lesions. In a choice situation where food could be obtained free or by working, lesioned Ss obtained significantly more reinforcement by bar pressing than by not working. This preference for obtaining reinforcement by bar pressing was evident in normal and operated Ss even when different amounts of effort (fixed ratios of l, 3, ll) were required to obtain reinforcement. When adulterated pellets were substituted for regular pellets, operated Ss continued to obtain significantly more reinforcement by bar pressing than normal Ss. Findings indicate the limitation of the explanation that rats with lesions in the ventromedial hypothalamus have reduced appetitive motivation or a general motivational deficit. (21 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)