Septal lesions and active avoidance performance in rats: effects of differential intrabox cues

In two separate experiments, male rats received septal lesions and were compared to operated controls on the acquisition of a two-way active avoidance task. In both experiments, an automated active avoidance apparatus (Lafayette Instrument Co.) was used, and the animals were tested 10 trials each day, 6 days/week. The CS was a tone, and the US was a 0.7 mA shock; the CS-US interval was 7 seconds. In Experiment 1, the rats (N = 6/group) were tested under conventional conditions. The two compartments of the avoidance apparatus were identical in all respects. In Experiment 2, the rats (N = 6/group) were tested in the same apparatus, but with differential intrabox cues. The inside of the left compartment was lined with black contact paper, while the inside of the right compartment was lined with white contact paper. Irrespective of the conditions, the septal rats were facilitated in the acquisition of shuttle-avoidance. In both tasks, the septal subjects required fewer trials to reach criterion, and showed better orientation in the shuttle-box compared to controls. The response latencies of the septal subjects also tended to be faster, but neither septal nor control subjects showed differential response latencies related to the direction of the shuttle response. Previous findings have shown that the addition of external cues to purported spatial tasks can reduce the behavioral effects produced by damage to the septohippocampal axis on such tasks. The present results suggest that such a cue-addition procedure does not influence the behavioral effects produced by septal lesions in shuttle-avoidance.