Operant conditioning after temporal lobe lesions in man: conditional and simple discrimination learning.

Temporal lobe lesions have been found to impair the acquisition of classical conditional discrimination learning in an eyelid conditioning paradigm, with sparing of simple eyelid conditioning. In the present study, subjects with left or right temporal resections were compared with normal controls on two operant conditioning tasks using a conditional and a simple discrimination paradigm analogous to the previously reported classical conditioning tasks. Subjects with right temporal lesions, and to a lesser extent those with left temporal lesions, were impaired relative to frontal lobe and control subjects in the acquisition of a conditional discrimination within an operant conditioning setting. A subsequent experiment showed that both left and right temporal lobe subjects were unimpaired on a simple operant discrimination task. These findings are compatible with theory relating hippocampal function to the learning of if-then rules.