EXTENDING MODELS OF HIPPOCAMPAL FUNCTION IN ANIMAL CONDITIONING TO HUMAN AMNESIA

Although most analyses of amnesia have focused on the loss of explicit declarative and episodic memories following hippocampal-region damage , considerable insights into amnesia can also be realised by studying hippocampal function in simple procedural, or habit-based, associative learning tasks. Although many simple forms of associative learning ar e unimpaired by hippocampal damage, more complex tasks which require s ensitivity to unreinforced stimuli, configurations of multiple stimuli , or contextual information are impaired by hippocampal damage. In sev eral recent papers we have developed a computational theory of hippoca mpal function which argues that this brain region plays a critical rol e in the formation of new stimulus representations during learning (Gl uck & Myers, 1993, 1995; Myers & Gluck, 1996; Myers, Gluck, & Granger, 1995). We have applied this theory to a broad range of empirical data from studies of classical conditioning in both intact and hippocampal -lesioned animals, and the model correctly accounts for these data. Th e classical conditioning paradigm can be adapted for use in humans, an d similar results for acquisition are obtained in both normal and hipp ocampal-damaged humans. More recently, we have begun to address an imp ortant set of category learning studies in both normals and hippocampa l-damaged amnesics. This work integrates experimental studies of amnes ic category learning (Knowlton, Squire, & Gluck, 1994) with theoretica l accounts of associative learning, and builds on previously establish ed behavioural correspondences between animal conditioning and human c ategory learning (Gluck & Bower, 1988a). Our work to date illustrates some initial progress towards a more integrative understanding of hipp ocampal function in both animal and human learning, which may be usefu l in guiding further empirical and theoretical research in human memor y and amnesia.