Hippocampal complex and retrieval of recent and very remote autobiographical memories: Evidence from functional magnetic resonance imaging in neurologically intact people

TLDR

The hippocampus is debated to be time‑limited in memory consolidation, yet some argue it remains essential for autobiographical memory regardless of age. The study aimed to assess hippocampal involvement in recalling recent versus very remote autobiographical events. Participants underwent fMRI while recalling autobiographical events from the past 4 years or over 20 years ago. Hippocampal activation was equivalent for recent and very remote memories, with no neocortical differences, supporting the hippocampus’s role in retrieving even very old autobiographical memories. © 2001 Wiley‑Liss, Inc.; Hippocampus 2001;11:707–714.

Abstract

Abstract It has been argued that the role of the hippocampus in memory is time‐limited: during a period of memory consolidation, other brain regions such as the neocortex are said to acquire the ability to support memory retention and retrieval on their own. An alternative view is that retention and retrieval of memory for autobiographical episodes depend on the hippocampal complex, regardless of the age of the memory. We examined the participation of the hippocampal complex in a functional magnetic resonance imaging (fMRI) study in which participants were asked to recollect autobiographical events that occurred either within the last 4 years or more than 20 years ago. We found equivalent levels of hippocampal activation in both conditions in all participants (N = 10). In addition, activation in neocortical regions did not differ as a function of the age of the memory, even though most of the recent memories recalled were less than 2 years old and the remote memories more than 35 years old. The results support the notion that the hippocampal complex participates in retention and recovery of even very old autobiographical memories, and place boundary conditions on theories of memory consolidation. Hippocampus 2001;11:707–714. © 2001 Wiley‐Liss, Inc.