Perceptual functions of perirhinal cortex in rats: zero-delay object recognition and simultaneous oddity discriminations.

Authors

Susan J Bartko, Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
Boyer D Winters, Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
Rosemary A Cowell, Laboratoire d'Etude de l'Apprentissage et du Developpement-Centre National de la Recherche Scientifique, Université de Bourgogne, 21065 Dijon, France
Lisa M Saksida, Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom & Medical Research Council and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, United Kingdom
Timothy J Bussey, Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom & Medical Research Council and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, United Kingdom

Document Type

Article

Publication Date

3-7-2007

Journal

The Journal of neuroscience : the official journal of the Society for Neuroscience

Volume

27

Issue

10

First Page

2548

Last Page

2559

URL with Digital Object Identifier

10.1523/JNEUROSCI.5171-06.2007

Abstract

The perirhinal cortex (PRh) is widely accepted as having an important role in object recognition memory in humans and animals. Contrary to claims that PRh mediates declarative memory exclusively, previous evidence suggests that PRh has a role in the perceptual processing of complex objects. In the present study, we conducted an examination of the possible role of PRh in perceptual function in rats. We examined whether bilateral excitotoxic lesions of PRh or PPRh (perirhinal plus postrhinal cortices) in the rat would cause deficits in a zero-delay object-recognition task and a simultaneous oddity discrimination task. Both of these tasks measured spontaneous (untrained, unrewarded) behavior, and the stimuli in these experiments were manipulated to produce varying levels of perceptual difficulty. As predicted by simulations using a computational model, rats with PPRh lesions were impaired in object recognition when the stimuli to be discriminated were manipulated to share many features in common. Furthermore, rats with PPRh and PRh lesions were impaired in a simultaneous oddity discrimination task when the stimuli to be discriminated were manipulated explicitly to be more perceptually similar. These findings provide support for the idea that PRh in the rat is important for the perceptual processing of complex objects, in addition to its well established role in memory.