Spatio-temporal organization of network activity patterns in the hippocampus

Abstract

The hippocampus is a layered brain network, composed of diverse cell types arranged in multiple microcircuits with anatomically structured inputs, all working in concert to support memory. This intricate organization generates a myriad of electrophysiological signatures. While specific aspects of these activity patterns have been explored, a comprehensive understanding of the hippocampal layer-embedded dynamics remains elusive. Here, we developed a low-dimensional manifold to capture electrophysiological patterns, mapping their anatomical trajectory along the CA1-to-DG axis, and distinguishing layers based on sharp-wave and theta profiles. This profiling led to the characterization of selective theta-nested gamma signatures for each layer. It further revealed spike patterns associated with gamma rhythms, which highlight specific firing motifs between principal cells and interneurons, and differential firing properties within pyramidal sub-layers. These findings support a holistic understanding of the spatio-temporal activity patterns across hippocampal layers for unraveling the network operations that drive memory-guided behavior.