Lesions of the perirhinal cortex impair sensory preconditioning in rats

The effects of lesions of the perirhinal cortex on the development of assoc iations between two conditioned stimuli (CSs) were examined with a sensory preconditioning procedure. Rats were given either bilateral electrolytic le sions of the perirhinal cortex or control surgery. They were then given eit her paired or unpaired presentations of a light CS and a tone CS. All of th e rats were then given eyeblink conditioning procedures that involved paire d presentations of either the light or tone and a periorbital shock uncondi tioned stimulus (US). The rats were finally given a test session that consi sted of unpaired presentations of the tone and light CSs. Sensory precondit ioning was established in the control group, but not in the lesion group. T he findings are consistent with the view that the perirhinal cortex is invo lved in forming associations between neutral stimuli (even in the absence o f reinforcement). (C) 2000 Elsevier Science B.V. All rights reserved.