Effects of dorsal and ventral hippocampal lesions on spontaneous alternation, learned alternation and probability learning in rats

Abstract

In a series of 3 experiments it was shown that lesions restricted to the dorsal or ventral portions of the hippocampus in rats produced different effects on behaviour. Animals with dorsal lesions perseverated on a spontaneous alternation task with a long inter-trial interval whereas those with ventral lesions alternated with a long delay and perseverated at short delays. On a probability learning task rats with dorsal lesions were indistinguishable from controls, whereas those with ventral lesions were impaired. When tested on lever-alternation the rats with dorsal hippocampal lesions were significantly superior to controls and those with ventral lesions were significantly impaired. The results are discussed in relation to the roˆle of dorsal hippocampus in attention and habituation and the ventral hippocampus in the mediation of response sets or strategies.