The human brain reactivates context-specific past information at event boundaries of naturalistic experiences

Hahamy et al. demonstrate that, at the transitions between narrative events, the human brain reactivates past information that is relevant for the understanding of the current narrative stage. Although we perceive the world in a continuous manner, our experience is partitioned into discrete events. However, to make sense of these events, they must be stitched together into an overarching narrative-a model of unfolding events. It has been proposed that such a stitching process happens in offline neural reactivations when rodents build models of spatial environments. Here we show that, while understanding a natural narrative, humans reactivate neural representations of past events. Similar to offline replay, these reactivations occur in the hippocampus and default mode network, where reactivations are selective to relevant past events. However, these reactivations occur, not during prolonged offline periods, but at the boundaries between ongoing narrative events. These results, replicated across two datasets, suggest reactivations as a candidate mechanism for binding temporally distant information into a coherent understanding of ongoing experience.

Automated summary

Hahamy et al. demonstrate that the human brain reactivates past relevant information at the transitions between narrative events to understand the current stage. This reactivation occurs in the hippocampus and default mode network, similar to offline replay in rodents. However, the reactivations occur at the boundaries between ongoing narrative events, rather than during prolonged offline periods. These results suggest that reactivations contribute to binding temporally distant information into a coherent understanding of ongoing experience.