Sleep-dependent decorrelation of hippocampal spatial representations

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2024
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© 2024 The Author(s)Neuronal ensembles are crucial for episodic memory and spatial mapping. Sleep, particularly non-REM (NREM), is vital for memory consolidation, as it triggers plasticity mechanisms through brain oscillations that reactivate neuronal ensembles. Here, we assessed their role in consolidating hippocampal spatial representations during sleep. We recorded hippocampus activity in rats performing a spatial object-place recognition (OPR) memory task, during encoding and retrieval periods, separated by intervening sleep. Successful OPR retrieval correlated with NREM duration, during which cortical oscillations decreased in power and density as well as neuronal spiking, suggesting global downregulation of network excitability. However, neurons encoding specific spatial locations (i.e., place cells) or objects during OPR showed stronger synchrony with brain oscillations compared to non-encoding neurons, and the stability of spatial representations decreased proportionally with NREM duration. Our findings suggest that NREM sleep may promote flexible remapping in hippocampal ensembles, potentially aiding memory consolidation and adaptation to novel spatial contexts.
Highlights: Spatial memory retrieval linearly correlates with non-REM sleep duration. Cortical oscillations and hippocampal unit spiking decrease during non-REM sleep. Place cells synchronize more with sleep oscillations than non-encoding cells. Stability of hippocampal spatial representations decreases during non-REM sleep.
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Behavioral neuroscience, Biological sciences, Cognitive neuroscience, Neuroscience, Systems neuroscience
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https://doi.org/10.1016/j.isci.2024.110076
 https://repositorio.uc.cl/handle/11534/87236
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