Vilde A. Kveim et al. ,Divergent recruitment of developmentally defined neuronal ensembles supports memory dynamics.Science 385,eadk0997(2024).DOI:10.1126/science.adk0997

Editor’s summary
“Memories are not fixed; they evolve after encoding and their content can be updated upon changes in external or internal contingencies. Kveim et al. investigated the mechanisms that govern the reorganization of neuronal ensembles linked to a specific memory and how these dynamic changes affect memory persistence over time. They found that in the hippocampal network, learning resulted in the parallel establishment of two distinct memory traces. These traces were represented in distinct neurogenesis-defined subpopulations of early- and late-born neurons. Even though temporally restricted, the transient recruitment of late-born neurons was necessary for a memory’s long-term permanence, whereas shifts in the recruitment of early- and late-born neurons had a strong impact on the plasticity of a recently acquired memory.” —Peter Stern

Abstract
“Memories are dynamic constructs whose properties change with time and experience. The biological mechanisms underpinning these dynamics remain elusive, particularly concerning how shifts in the composition of memory-encoding neuronal ensembles influence the evolution of a memory over time. By targeting developmentally distinct subpopulations of principal neurons, we discovered that memory encoding resulted in the concurrent establishment of multiple memory traces in the mouse hippocampus. Two of these traces were instantiated in subpopulations of early- and late-born neurons and followed distinct reactivation trajectories after encoding. The divergent recruitment of these subpopulations underpinned gradual reorganization of memory ensembles and modulated memory persistence and plasticity across multiple learning episodes. Thus, our findings reveal profound and intricate relationships between ensemble dynamics and the progression of memories over time.”

Vilde A. Kveim et al. ,Divergent recruitment of developmentally defined neuronal ensembles supports memory dynamics.Science 385,eadk0997(2024).DOI:10.1126/science.adk0997