Amygdalectomy and mixed reinforcement schedule contrast effects

Abstract

Four controls and four amygdalectomized rats were trained to leverpress on a mixed schedule of reinforcement in which 5 min of variable-interval reinforcement alternated with 5 min of extinction. Control animals increased responding in the variable-interval component over baseline rates (i.e., behavioral contrast), whereas amygdalectomized animals did not. No significant differences between groups were found during extinction. The lack of contrast effects in amygdaloid animals was attributed to a reduction in extinction-induced frustration.