Septal lesion effects on a two-way avoidance task with one-way avoidance task characteristics: A test of a fear-attenuation hypothesis

Abstract

Two experiments were conducted to assess the hypothesis that septal lesions result in a decrement in conditioned fear and to investigate whether the different effects of septal lesions in one-way and two-way avoidance tasks are due to some procedural differences between these two tasks_ Experiment 1 compared the septal and normal control rats in a two-way avoidance task that incorporated a safe platform under the subject after a response but did not involve handling the subject (one-way analogue task). Experiment 2 investigated the effects of septal lesions in conventional two-way and one-way analogue tasks with two levels of shock intensity. The results indicated that, in the absence of a moving partition or electrified grids on top of the hurdle, the one-way analogue task enhanced the performance of both the normals and septa Is with both levels of shock intensity. Shock intensity had no effect in the one-way analogue task, but the more intense shock degraded the performance of both septals and normals in the two-way task. These results are not predicted by the fear-attenuation hypothesis. An alternative hypothesis in terms of the septals' deficiency in the utilization of spatial cues was tested and shown able to account for all of the present results.