Hippocampal engrams generate flexible behavioral responses and brain-wide network states

• DOI: 10.1101/2023.02.24.529744
• Publication Date: 2023-02-25T04:00:11Z
• Authors: Kaitlyn E. Dorst; Ryan A. Senne; Anh H. Diep; Antje R. de Boer; Rebecca L. Suthard; Heloise Leblanc; Evan A. Ruesch; Sara Skelton; Olivia P. McKissick; John H. Bladon; Steve Ramirez
• Keywords: Engram

ABSTRACT Memory engrams are both necessary and sufficient to mediate behavioral outputs. Defensive behaviors such as freezing avoidance commonly examined during hippocampal-mediated fear engram reactivation, yet how reactivation of these cellular populations across different contexts engages the brain produce a variety defensive is relatively unclear. To address this, we first optogenetically reactivated tagged in dentate gyrus (DG) subregion hippocampus three distinct contexts. We found that there were differential amounts light-induced depending on size context which occurred: mice demonstrated robust most spatially restricted but not largest. then utilized graph theoretical analyses identify brain-wide alterations cFos co-activation smallest largest Our manipulations conferred greater positive correlations recruited regions spanning putative defense systems hubs respective networks. Moreover, reactivating DG-mediated generated network topologies experimental conditions, emphasizing shared features. By identifying manipulating circuits supporting memory function, well their corresponding activity patterns, it thereby possible resolve systems-level biological mechanisms mediating memory’s capacity modulate states. SIGNIFICANCE STATEMENT Implementing appropriate disparate environments essential for survival. Memories can be used select responses. Recent work identified artificially manipulated ensembles within recall, engage pathways under environmental contingencies here various sizes elicits responses dynamics. These findings establish flexibility memory-bearing generating behavior