Behavioral evidence for memory replay of video episodes in macaque monkeys

Abstract

148 WORDS) 2 5Humans recall the past by replaying fragments of events temporally. Here, we 2 6 demonstrate a similar effect in macaques. We trained six rhesus monkeys with a 2 7 temporal-order judgement (TOJ) task and collected 5000 TOJ trials. In each trial, they 2 8 watched a naturalistic video of about 10 s comprising two across-context clips, and 2 9 after a 2-s delay, performed TOJ between two frames from the video. The monkeys 3 0 apply a non-linear forward, time-compressed replay mechanism during the 3 1 temporal-order judgement. In contrast with humans, such compression of replay is 3 2 however not sophisticated enough to allow them to skip over irrelevant information 3 3 by compressing the encoded video globally. We also reveal that the monkeys detect 3 4 event contextual boundaries and such detection facilitates recall by an increased rate 3 5 of information accumulation. Demonstration of a time-compressed, forward replay 3 6 like pattern in the macaque monkeys provides insights into the evolution of episodic 3 7 memory in our lineage. 3 8 3 9