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Evidence for the incorporation of temporal duration information in human hippocampal long-term memory sequence representations.

Evidence for the incorporation of temporal duration information in human hippocampal long-term memory sequence representations.

Authors :
Thavabalasingam S
O'Neil EB
Tay J
Nestor A
Lee ACH
Source :
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2019 Mar 26; Vol. 116 (13), pp. 6407-6414. Date of Electronic Publication: 2019 Mar 12.
Publication Year :
2019

Abstract

There has been much interest in how the hippocampus codes time in support of episodic memory. Notably, while rodent hippocampal neurons, including populations in subfield CA1, have been shown to represent the passage of time in the order of seconds between events, there is limited support for a similar mechanism in humans. Specifically, there is no clear evidence that human hippocampal activity during long-term memory processing is sensitive to temporal duration information that spans seconds. To address this gap, we asked participants to first learn short event sequences that varied in image content and interval durations. During fMRI, participants then completed a recognition memory task, as well as a recall phase in which they were required to mentally replay each sequence in as much detail as possible. We found that individual sequences could be classified using activity patterns in the anterior hippocampus during recognition memory. Critically, successful classification was dependent on the conjunction of event content and temporal structure information (with unsuccessful classification of image content or interval duration alone), and further analyses suggested that the most informative voxels resided in the anterior CA1. Additionally, a classifier trained on anterior CA1 recognition data could successfully identify individual sequences from the mental replay data, suggesting that similar activity patterns supported participants' recognition and recall memory. Our findings complement recent rodent hippocampal research, and provide evidence that long-term sequence memory representations in the human hippocampus can reflect duration information in the order of seconds.<br />Competing Interests: The authors declare no conflict of interest.

Details

Language :
English
ISSN :
1091-6490
Volume :
116
Issue :
13
Database :
MEDLINE
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
30862732
Full Text :
https://doi.org/10.1073/pnas.1819993116