Spatial and object reversal learning in monkeys with partial temporal lobe ablations

Effects of frontal and combined medial temporal, or amygdala and hippocampal lesions separately, were compared on delayed alternation, delayed response, spatial and object reversals and non-spatial delayed alternation. Failure on spatial delayed alternation but not delayed response characterized all monkeys with temporal lobe lesions. Frontal, medial temporal and amygdala lesions resulted in varying degrees of impairment on spatial and object reversals, while hippocampal lesion produced a deficit on spatial but not object reversals. All monkeys with temporal lobe lesions achieved normal learning scores on nonspatial delayed alternation, but hippocampal monkeys were most efficient. The effects of medial temporal lesions are discussed in terms of the relative contributions of the amygdala and hippocampal ablations to the total syndrome.