Humans recall the past by replaying fragments of events temporally. Here, we demonstrate a similar effect in macaques. We trained six rhesus monkeys with a temporal-order judgement (TOJ) task and collected 5000 TOJ trials. In each trial, they watched a naturalistic video of about 10 s comprising two across-context clips, and after a 2-s delay, performed TOJ between two frames from the video. The data is suggestive of a non-linear, time-compressed forward memory replay mechanism in the macaque. In contrast with humans, such compression of replay is however not sophisticated enough to allow them to skip over irrelevant information by compressing the encoded video globally. We also reveal that the monkeys detect event contextual boundaries and such detection facilitates recall by an increased rate of information accumulation. Demonstration of a time-compressed, forward replay-like pattern in the macaque provides insights into the evolution of episodic memory in our lineage.
- Yong-di Zhou
- Sze Chai Kwok
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: The experimental protocol was approved by the Institutional Animal Care and Use Committee (permission code: M020150902 & M020150902-2018) at East China Normal University. All experimental protocols and animal welfare adhered with the "NIH Guidelines for the Care and Use of Laboratory Animals".
Human subjects: The experimental protocol was approved by the the University Committee on Human Research Protection (permission code: HR 023-2017) at East China Normal University. . The participants provided informed consent.
- Morgan Barense, University of Toronto, Canada
© 2020, Zuo et al.
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