Integrating new memories into the hippocampal network activity space.

Gava GP
McHugh SB
Lefèvre L
Lopes-Dos-Santos V
Trouche S
El-Gaby M
Schultz SR
Dupret D

When the brain forms new memories, what happens to the other, older memories? Here, we report that in a part of the brain called the hippocampus, the flexible reorganisation of nerve cell activity representing existing memories allows for embedding of new memories.

Scientific Abstract

By investigating the topology of neuronal co-activity, we found that mnemonic information spans multiple operational axes in the mouse hippocampus network. High-activity principal cells form the core of each memory along a first axis, segregating spatial contexts and novelty. Low-activity cells join co-activity motifs across behavioral events and enable their crosstalk along two other axes. This reveals an organizational principle for continuous integration and interaction of hippocampal memories.

Picture of stars in the night sky, with lines drawn between the stars. The stars and lines represent nerve cells and their connections that support the reorganisation of brain activity to support the continuous integration and interaction of memories.
A set of connected stars in the night sky to illustrate Gava and colleagues’ use of a graph-theoretical approach to study how the topological reorganization of neuronal cofiring supports continuous integration and interaction of memories in the hippocampal "network activity space".

2021. Nat Neurosci, 24(3):326-330.

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