Event structure sculpts neural population dynamics in the lateral entorhinal cortex

Our experience of the world is a continuous stream of events that must be segmented and organized at multiple timescales. The neural mechanisms underlying this process remain unknown. In this work, we simultaneously recorded hundreds to thousands of neurons in the lateral entorhinal cortex of freely behaving rats. Neural population activity drifted continuously along a one-dimensional manifold during all behaviors and behavioral states, including sleep, which points to an intrinsic origin of the drift. In awake animals, boundaries between events were associated with discrete shifts in population dynamics, which segmented the neural activity into temporal units. During tasks with recurring temporal structure, activity traveled additionally in directions orthogonal to the drift, encoding event information across multiple timescales. The results identify a hierarchical coding scheme for organizing events in time.