Effects of hippocampal lesions in a food location task in pigeons

This study investigated the role of the hippocampus in pigeons learning of a food-related choice task. The effects of lesions induced by ibotenic acid were analyzed in two experiments. Experiment 1 investigated the effects of hippocampal damage on postoperative memory retrieval and in reversal learning. Experiment 2 investigated the effects of hippocampal lesions on the acquisition and reversal of learning. In both experiments probe tests were used to assess the behavioral strategies underlying the choice. In Experiment 1 hippocampal lesions impaired the preoperative learned performance in terms of choice latency but not choice accuracy. Experiment 2 data showed that, in postoperative learning sessions, latency as well as choice accuracy were impaired by hippocampal damage. The probe tests, in which a curtain was placed around the chamber, revealed behavioral patterns of a non-mapping strategy. This was true in both experiments and groups (experimental and controls). Immediately after training, during the probe tests of both experiments, in which food cups were omitted, the three groups spent more time in the target quadrant. However, immediately after the reversal condition, neither hippocampal damaged nor control pigeons showed a preference for the target quadrant. This may be interpreted as evidence for a hippocampal role in stimulus location learning involving non-mapping strategies.