EFFECTS OF CS PREEXPOSURES ON AVOIDANCE LEARNING IN RATS WITH HIPPOCAMPAL LESIONS

36 male Long-Evans hooded rats with hippocampal, neocortical, or no lesions received either 0 or 30 presentations of a stimulus later used as CS in a 2-way shuttle-avoidance task. The 30 preexposures slowed acquisition of the avoidance response and speeded its extinction in the unoperated controls and in the group with neocortical lesions, but not in the group with hippocampal lesions. The latter group did not differ on either measures from any of the subgroups that received 0 preexposures, none of which differed from each other. Results support models attributing an inhibitory function to the hippocampus and suggest an attentional involvement in the preexposure effect. (29 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.