Abstract
Reinstatement of dynamic memories requires the replay of neural patterns that unfold over time in a similar manner as during perception. However, little is known about the mechanisms that guide such a temporally structured replay in humans, because previous studies used either unsuitable methods or paradigms to address this question. Here, we overcome these limitations by developing a new analysis method to detect the replay of temporal patterns in a paradigm that requires participants to mentally replay short sound or video clips. We show that memory reinstatement is accompanied by a decrease of low-frequency (8 Hz) power, which carries a temporal phase signature of the replayed stimulus. These replay effects were evident in the visual as well as in the auditory domain and were localized to sensory-specific regions. These results suggest low-frequency phase to be a domain-general mechanism that orchestrates dynamic memory replay in humans.
Highlights
IntroductionMultisensory events that are coded in our memory system
Episodic memories are dynamic, multisensory events that are coded in our memory system
If one remembers the last movie one has seen, one can vividly evoke parts of this event in a temporally highly structured manner. This implicates a neural mechanism that temporally guides the brain through memory retrieval as a sensory trace unfolds over time
Summary
Multisensory events that are coded in our memory system. Whenever we re-experience episodic memories this way, the events unravel in front of our mind in a temporal order Even subparts of these episodes, such as the movement of lips in a conversation or parts of the background melody, have an inherent temporal dynamic to them. Given this abundance of temporal structure in our memories, it is rather surprising how limited our understanding is as to how human brains orchestrate such dynamic memory replay. We address this question for the first time, to our knowledge, and identify a neural mechanism that carries the temporal signature of individual dynamic episodic memories. Temporal signatures were carried by a frequency that was markedly similar in two sensory domains (~8 Hz), they appeared in sensoryspecific regions, and they were related to decreases in power in the same frequency
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