INTEGRATING BEHAVIORAL AND PHYSIOLOGICAL MODELS OF HIPPOCAMPAL FUNCTION

In recent modeling of hippocampal function, we have attempted to integ rate formal behavioral analyses of classical conditioning with psychob iological data on brain lesions (Cluck and Myers [1993] Hippocampus 3: 491-516; Myers and Cluck [1994] Behav Neurosci 108(5):835-847). Based on comparative behavioral analyses, we have argued that animals with h ippocampal region damage are unable to alter stimulus similarity based on experience. While hippocampal-damaged animals can still learn whet her to respond to an individual stimulus, they are notably impaired at many tasks involving learning relationships between stimuli-especiall y in the absence of explicit reinforcement. These analyses lead to a c omputational theory which identifies two representational recoding pro cesses-predictive differentiation and redundancy compression-which aft er stimulus similarity relationships in intact animals but are depende nt on intact hippocampal region processing. More recent, and ongoing, modeling aims to broaden this model of hippocampal region function in classical conditioning, with an emphasis on physiological and anatomic al constraints, including the role of the fornix and subcortical modul ation, preprocessing in sensory cortices, and localization of the prop osed representational functions within more precisely identified hippo campal region substrates (Myers et al. [1995] Psychology 23(2):116-138 ; Myers and Cluck [1996] Behav Neurosci; Myers et al. [1996] Neurobiol Learning Memory). Working to bridge between behavioral and physiologi cal levels of analysis, we ultimately hope to develop a more complete understanding of hippocampal region function in memory across a wider range of behavioral paradigms, elucidating how this functionality emer ges from underlying physiological and anatomical substrates. (C) 1997 Wiley-Liss, Inc.