HUMAN HIPPOCAMPUS ESTABLISHES ASSOCIATIONS IN MEMORY

Studies of amnesia have demonstrated that the hippocampus is necessary for long-term memory, but its precise role in memory is unknown. We d esigned a positron emission tomography experiment with tailored encodi ng and retrieval tasks that permitted the isolation of different mnemo nic functions theorized to be mediated by the hippocampus. These funct ions included encoding single items, establishing interitem associatio ns, novelty detection, and retrieving recently formed associations. Of these, we found hippocampal and parahippocampal activation only durin g associative learning. Our results indicate that the hippocampal form ation may be particularly involved in the establishment of association s among components of an episode in memory. (C) 1997 Wiley-Liss, Inc.