DIFFERENTIATING THE ROLES OF THE HIPPOCAMPAL COMPLEX AND THE NEOCORTEX IN LONG-TERM-MEMORY STORAGE - EVIDENCE FROM THE STUDY OF SEMANTIC DEMENTIA AND ALZHEIMERS-DISEASE

Several computational models suggest that the hippocampal complex play s a key role in the establishment of new memories, but over time the s torage of such memories becomes independent of this region. In support of such models, the authors demonstrate that patients with semantic d ementia, who have relative sparing of the hippocampal complex, show a pattern of preserved recent memories and impaired distant memories. In a group study that used the Autobiographical Memory Interview, amnesi c patients with Alzheimer's disease showed the more typical temporally graded loss (poor recall of recent memories), whereas patients with s emantic dementia showed the reverse pattern. In a single-case study, u sing the Galton-Crovitz test, a patient with semantic dementia was sig nificantly better at producing autobiographical memories from the most recent 5 years. By contrast, controls provided similarly detailed mem ories across all time periods back to childhood.