The study examines the temporal coordination of pyramidal cell spikes in the rat hippocampus during slow-wave sleep and wheel running. Using a template-matching method and a joint probability map method, researchers identified repeating spike sequences that were more frequent than expected by chance. These sequences were present in both awake and sleeping animals, suggesting they are internally generated. During wheel running, the observed spike sequences were "replayed" at a faster timescale during sharp-wave bursts of slow-wave sleep. The findings suggest that these sequences reflect reactivation of circuitry modified by previous experience, potentially serving to consolidate information. The study also discusses the physiological role of spike sequence replay, proposing that it may facilitate Hebbian synaptic plasticity or activate relevant target neurons downstream from the hippocampus.The study examines the temporal coordination of pyramidal cell spikes in the rat hippocampus during slow-wave sleep and wheel running. Using a template-matching method and a joint probability map method, researchers identified repeating spike sequences that were more frequent than expected by chance. These sequences were present in both awake and sleeping animals, suggesting they are internally generated. During wheel running, the observed spike sequences were "replayed" at a faster timescale during sharp-wave bursts of slow-wave sleep. The findings suggest that these sequences reflect reactivation of circuitry modified by previous experience, potentially serving to consolidate information. The study also discusses the physiological role of spike sequence replay, proposing that it may facilitate Hebbian synaptic plasticity or activate relevant target neurons downstream from the hippocampus.