Passive avoidance learning in hippocampectomized rats under different shock and intertrial interval conditions

Abstract

Two experiments were run comparing the performance of normal, cortically damaged and hippocampally damaged rats on a passive avoidance task [37]. The results of Experiment 1 indicated that hippocampally damaged rats learn to passively avoid after no more than three consecutive punishment trials. In Experiment 2, the passive avoidance performance of groups of normal, cortically damaged, or hippocampally damaged rats was studied using a factorial combination of two intertrial intervals (60 sec and 60 min) and two shock intensities (1.8 mA and 1.8 mA). Results indicated that the greatest and most persistent deficits in the performance of hippocampally ablated animals occurred in the low shock, short intertrial interval condition. No differences between the performance of hippocampally damaged animals and control animals were found in the high shock, long intertrial interval condition. Performance of the hippocampectomized animals in the remaining groups was poorer than controls, but intermediate between the performance of the hippocampal animals in the aforementioned groups. Results were interpreted as supporting an information processing model of hippocampal function.