Replay and Time Compression of Recurring Spike Sequences in the Hippocampus

By Zoltan Nadasdy, H. Hirase, András Czurkó, J. Csicsvari, György Buzsáki. 1999

Information in neuronal networks may be represented by the spatiotemporal patterns of spikes. Here we examined the temporal coordination of pyramidal cell spikes in the rat hippocampus during slow-wave sleep. In addition, rats were trained to run in a defined position in space (running wheel) to activate a selected group of pyramidal cells. A template-matching method and a joint probability map method were used for sequence search. Repeating spike sequences in excess of chance occurrence were examined by comparing the number of repeating sequences in the original spike trains and in surrogate trains after Monte Carlo shuffling of the spikes. Four different shuffling procedures were used to control for the population dynamics of hippocampal neurons. Repeating spike sequences in the recorded cell assemblies were present in both the awake and sleeping animal in excess of what might be predicted by random variations. Spike sequences observed during wheel running were “replayed” at a faster timescale during single sharp-wave bursts of slow-wave sleep. We hypothesize that the endogenously expressed spike sequences during sleep reflect reactivation of the circuitry modified by previous experience. Reactivation of acquired sequences may serve to consolidate information.

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Citations in the corpus

How to Represent Part-Whole Hierarchies in a Neural Network (2021, background): “There is evidence that high-speed, top-down sequence generation occurs during the spindle stage of sleep [Lee and Wilson, 2002, N´adasdy et al., 1999].”
Replay in Deep Learning: Current Approaches and Missing Biological Elements (2021, positive): “Furthermore, many existing artificial replay implementations do not purge their memory buffer, which is not consistent with biology (Nádasdy et al., 1999; Karlsson & Frank, 2009) and do not have a notion of waking (streaming/online) learning.”
Awake replay of remote experiences in the hippocampus (2009, neutral): “Complementary studies have shown that entire sequences can be replayed at high speeds14–16, 19.”
Hippocampal replay of extended experience (2009, neutral): “Replay events have consistently been found to co-occur with ripple oscillations in the hippocampal local field potential (Diba and Buzsáki, 2007; Foster and Wilson, 2006; Ji and Wilson, 2007; Lee and Wilson, 2002; Nádasdy et al., 1999).”
Temporally structured replay of awake hippocampal ensemble activity during rapid eye movement sleep. (2001, background): “Note that the combination of spatial seconds to seconds (Abeles and Gerstein, 1988; Abeles et al., 1993; Nadasdy et al., 1999), we examined neuralreceptive fields and structured spatial behavior pro- duces a characteristic ordered pattern of ensemble ac- activity at a lower temporal resolution but…”
Learned material content and acquisition level modulate cerebral reactivation during posttraining rapid-eye-movements sleep (2003, result): “Consistent with this hypothesis, several animal studies have shown that neural activity expressed during waking behavior is reinstated during subsequent sleep (e.g., Wilson and McNaughton, 1994; Skaggs and McNaughton, 1996; Qin et al., 1997; Nadasdy et al., 1999; Louie and Wilson, 2001).”
ReviewMemory Consolidation in Sleep: Dream or Reality (2004, background): “As discussed, however, 1999; Nadasdy et al., 1999; Hirase et al., 2001; LouieDonchin et al. (2002) described consolidation (as stabiliand Wilson, 2001; Hoffman and McNaughton, 2002; Leezation) for an arm reaching task but were unable to show and Wilson, 2002).”
Temporal encoding of place sequences by hippocampal cell assemblies. (2006, background): “…learned neuronal sequences of place fields are spontaneously replayed during immobility and sleep-related sharp wave bursts (Wilson and McNaughton, 1994; Nadasdy et al., 1999; Lee and Wilson, 2002) without extrahippocampal influences at a time scale slightly faster than during a given theta cycle.”
The content of hippocampal “replay” (2018, background): “In addition, the studies on ensemble reactivation consistently reported that sleepbased sequences were temporally compressed when compared to their corresponding waking sequences (Ji & Wilson, 2007; Lee & Wilson, 2002; N adasdy et al., 1999).”
New experiences enhance coordinated neural activity in the hippocampus. (2008, unknown): “Neurons with overlapping place fields tend to fire together when the animal is located outside the place fields during later periods of sleep (Pavlides and Winson, 1989; Wilson and McNaughton, 1994; Skaggs and McNaughton, 1996; Nadasdy et al., 1999; Kudrimoti et al., 1999; Louie and Wilson, 2001; Le”