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The neural correlates of recollection: Hippocampal activation declines as episodic memory fades
Author(s) -
Viskontas Indre V.,
Carr Valerie A.,
Engel Stephen A.,
Knowlton Barbara J.
Publication year - 2009
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.20503
Subject(s) - episodic memory , subiculum , recall , psychology , hippocampus , cognitive psychology , temporal lobe , hippocampal formation , autobiographical memory , semantic memory , neuroscience , explicit memory , recognition memory , cognition , dentate gyrus , epilepsy
Memories for certain events tend to linger in rich, vivid detail, and retrieval of these memories includes a sense of re‐experiencing the details of the event. Most events, however, are not retained in any detailed way for more than a few days. According to one theory, the hippocampus plays a specific role in supporting episodic retrieval, that is, the re‐experiencing of an event as part of one's personal past. This theory predicts that as episodic memories fade over time and are reduced to feelings of familiarity, activity in the hippocampus should no longer be associated with retrieval. We used high‐resolution functional imaging to explore neural activity in medial temporal lobe subregions while participants performed a recognition task at both a short (10‐min) and long (1‐week) study‐test delay. For each recognized item, subjects made “Remember/Know” judgments, allowing us to distinguish between items that were consistently episodic across the two tests and items that were initially episodic, but later became merely familiar. Our results demonstrate that activity in the subiculum is specifically associated with episodic recollection. Overall, recollected items were associated with higher activity in the subiculum than other items. For transiently recollected items, there was a decrease in subicular activity across the 1‐week delay as memory faded from recollection to familiarity, whereas consistently recollected items were associated with enhanced subicular activity at both delays. These results provide evidence of a link between subicular activation and recollective experience. © 2008 Wiley‐Liss, Inc.