Fast-backward replay of sequentially memorized items in humans

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Abstract

Storing temporal sequences of events (i.e., sequence memory) is fundamental to many cognitive functions. However, how the sequence order information is maintained and represented in working memory and its behavioral significance, particularly in human subjects, remains unknown. Here, we recorded electroencephalography (EEG) in combination with a temporal response function (TRF) method to dissociate item-specific neuronal reactivations. We demonstrate that serially remembered items are successively reactivated during memory retention. The sequential replay displays two interesting properties compared to the actual sequence. First, the item-by-item reactivation is compressed within a 200-400 ms window, suggesting that external events are associated within a plasticity-relevant window to facilitate memory consolidation. Second, the replay is in a temporally reversed order and is strongly related to the recency effect in behavior. This fast-backward replay, previously revealed in rat hippocampus and demonstrated here in human cortical activities, might constitute a general neural mechanism for sequence memory and learning.

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All data generated during this study are included in the manuscript and supporting files.

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Author details

Qiaoli Huang

School of Psychological and Cognitive Sciences, Peking University, Beijing, China

For correspondence
qiaolihuang@pku.edu.cn

Competing interests
The authors declare that no competing interests exist.
Jianrong Jia

School of Psychological and Cognitive Sciences, Peking University, Beijing, China

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-7665-1182
Qiming Han

School of Psychological and Cognitive Sciences, Peking University, Beijing, China

Competing interests
The authors declare that no competing interests exist.
Huan Luo

School of Psychological and Cognitive Sciences, Peking University, Beijing, China

For correspondence
huan.luo@pku.edu.cn

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-8349-9796

Funding

National Natural Science Foundation of China (31522027)

Huan Luo

National Natural Science Foundation of China (31571115)

Huan Luo

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: All participants provided written informed consent prior to the start of the experiment, which was approved by the Research Ethics Committee at Peking University (2015-03-05c2).

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.