PERIRHINAL CORTEX ABLATION IMPAIRS CONFIGURAL LEARNING AND PAIRED-ASSOCIATE LEARNING EQUALLY

Combined damage to the perirhinal and entorhinal cortex has been impli cated in tie formation of stimulus-stimulus associative memories. We s how in this article that relative to three normal controls three cynom olgus monkeys with ablations restricted to the perirhinal cortex were impaired on a visual paired-associate learning task in which subjects had to learn which of two visual stimuli were associated with a cue st imulus. The subjects with perirhinal cortex ablations also showed an i mpairment of a similar magnitude on a visual configural learning task in which they had to learn which of two configurations of visual stimu li were associated with food-reward. The stimuli in both tasks were co mprised of alphanumeric characters presented upon a touch-screen. Both groups made fewer errors on the configural learning task than on the paired-associate learning task. We suggest that performance on both ta sks relies critically on the perirhinal cortex due to the specializati on of the perirhinal cortex in processing knowledge about objects. We argue that the specializations of this system and of other memory syst ems such as the hippocampal-fornix spatial/episodic memory system, are conferred by the specialization of their anatomical connections to ot her structures. We reject the notion that there are specific memory pr ocesses such as the hippocampal based configural associative system th at was proposed to be critical for configural associative learning. (C ) 1998 Elsevier Science Ltd. All rights reserved.