Exercise accelerates place cell representational drift

• Published in: Current biology Vol. 33; no. 3; pp. R96 - R97
• Main Authors: de Snoo, Mitchell L., Miller, Adam M.P., Ramsaran, Adam I., Josselyn, Sheena A., Frankland, Paul W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 06-02-2023
• Subjects: Animals; Dentate Gyrus - physiology; Hippocampus - physiology; Mice; Mice, Inbred C57BL; Neurogenesis - physiology; Neurons - physiology; Place Cells
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2022.12.033

Stable neural ensembles are often thought to underlie stable learned behaviors and memory. Recent longitudinal experiments, however, that tracked the activity of the same neurons over days to weeks have shown that neuronal activity patterns can change over extended timescales even if behaviors remain the same — a phenomenon termed representational drift1. We have tested whether neural circuit remodeling, defined as any change in structural connectivity, contributes to representational drift. To do this, we tracked how hippocampal CA1 spatial representations of a familiar environment change with time in conventionally housed mice relative to mice housed with a running wheel. Voluntary exercise is an environmental stimulus that promotes hippocampal circuit remodeling, primarily via promoting adult neurogenesis in the dentate gyrus. Adult neurogenesis alters structural connectivity patterns, as the integration of adult-generated granule cells (abGCs) is a competitive process where new input–output synaptic connections may co-exist and/or even replace existing synaptic connections2. Comparing the spatial activity of downstream hippocampal CA1 place cells in the same familiar environment over two weeks, we found that the activity of place cells in exercise mice exhibited accelerated representational drift compared to control mice, suggesting that hippocampal circuit remodeling may indeed drive representational drift.
Representational drift is broadly observed in the brain but the mechanisms that drive it are unknown. de Snoo et al. report that voluntary exercise, a behavioral intervention associated with neural circuit remodeling, is sufficient to accelerate representational drift in CA1 place cells.