Deficits on conditional associative-learning tasks after frontal- and temporal-lobe lesions in man.

Patients with unilateral frontal- or temporal-lobe excisions were tested on a spatial and a nonspatial conditional associative task. These tasks required the learning of arbitrary associations between a set of stimuli and a set of responses. Patients with excisions from the left or right frontal cortex were severely impaired in learning both tasks. Patients with left or right temporal-lobe excisions that did not involve extensive damage to the hippocampal region were not impaired, whilst those with more radical involvement of the hippocampal region exhibited deficits that were material-specific and varied with the side of the lesion.