Right hippocampal excision impairs learning and recall of a list of abstract designs.

The role of the temporal lobes and the hippocampus in learning a list of abstract designs was investigated. Variables studied included trials to criterion, 24-hr delayed recall and serial-position effects. Normal control subjects and four groups of patients, classified according to side of temporal lobectomy and extent of excision from the hippocampal zone, were tested. Patients with a right temporal lobectomy that included a large hippocampal excision showed deficient learning and memory, and, on the serial-position analysis, they recalled essentially none of the first items of the list. The other patient groups were unimpaired, except in the number of trials required to reach criterion.