EFFECTS OF DIFFERENTIAL HIPPOCAMPAL LESIONS ON A SHOCK VERSUS SHOCK CONFLICT

Rats with hippocampal damage, neocortical damage, sham lesions, or no damage (unoperated controls) were first trained to actively avoid shock in a one-way avoidance apparatus, then trained to inhibit this response (i.e., passively avoid) after one shock trial in the previously safe goal area. Damage to the hippocampus was induced by either aspiration (large) or electrolytic (small) techniques. Rats with large hippocampal lesions were deficient on both the active and passive avoidance measures as compared to the other four groups tested, none of which significantly differed from each other. The results are discussed in terms of massing versus distribution of training experience, as well as size of lesion. © 1969.