Learning and Retention in Monkeys After Amygdala-Hippocampus Resection

In 1899 Bechterew³ demonstrated a case of bilateral softening of the gyrus uncinatus and cornu ammonis before members of the St. Petersburg Clinic and drew attention to the prominent memory disturbances. Over 50 years later, Glees and Griffith⁸ described an instance of dementia with bilateral destruction of the hippocampus and hippocampal gyrus in which recent memory impairment was an early and prominent symptom. They concluded on the basis of the necropsy material that the integrity of the region of the hippocampus is necessary for the maintenance of recent memory. Since then, a series of clinical studies has provided corroborative evidence and has extended these findings. In 1954, Scoville³⁵ reported a grave loss of recent memory in one epileptic and one psychotic patient after bilateral surgical removal of the uncus, hippocampus, and hippocampal gyrus. Formal memory and intelligence testing of eight similar patients again indicated impairment in recent