Discovering Event Structure in Continuous Narrative Perception and Memory

During realistic, continuous perception, humans automatically segment experiences into discrete events. Using a novel model of cortical event dynamics, we investigate how cortical structures generate event representations during narrative perception and how these events are stored to and retrieved from memory. Our data-driven approach allows us to detect event boundaries as shifts between stable patterns of brain activity without relying on stimulus annotations and reveals a nested hierarchy from short events in sensory regions to long events in high-order areas (including angular gyrus and posterior medial cortex), which represent abstract, multimodal situation models. High-order event boundaries are coupled to increases in hippocampal activity, which predict pattern reinstatement during later free recall. These areas also show evidence of anticipatory reinstatement as subjects listen to a familiar narrative. Based on these results, we propose that brain activity is naturally structured into nested events, which form the basis of long-term memory representations. •Event boundaries during perception can be identified from cortical activity patterns•Event timescales vary from seconds to minutes across the cortical hierarchy•Hippocampal activity following an event predicts reactivation during recall•Prior knowledge of a narrative enables anticipatory reinstatement of event patterns Using a new approach for identifying temporal structure in neuroimaging data, Baldassano et al. propose a theory of how continuous experience is divided into events that are represented in high-level cortex, are stored in long-term memory, and influence later perception.