Neural Markers of Event Boundaries

The continuous flow of sensorimotor experience is segmented into events that are stored in memory as discrete representations. These events are subsequently available for reconstruction into episodic memories or to be recombined for future thinking, prediction and imagination. Here we briefly review the patterns of brain activity that accompany the processing of events, and the transitions between them, with an aim to identifying signals that would serve as event boundary markers (EBMs). Since many previous studies have highlighted a role for the hippocampus in episodic memory function, consolidation and future thinking, we focus on activity in this region. In particular, we describe the brief bursts of hippocampal activity known as sharp-wave ripples (SWRs), which tend to occur following the cessation of units of behavior, making them putative EBM candidates. While most current models of SWR function tend to focus on a potential role in memory consolidation or preplay linked to future thinking, here we consider an interpretation that incorporates an EBM component.