Cited by 173Memory and Neural MechanismsSleep and Wakefulness ResearchNeural dynamics and brain function

Hippocampal Sharp Wave/Ripples during Sleep for Consolidation of Associative Memory

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Ramadan, Wiâm, Eschenko, Oxana, Sara, Susan J.·2009·PLoS ONE

Abstract

The beneficial effect of sleep on memory has been well-established by extensive research on humans, but the neurophysiological mechanisms remain a matter of speculation. This study addresses the hypothesis that the fast oscillations known as ripples recorded in the CA1 region of the hippocampus during slow wave sleep (SWS) may provide a physiological substrate for long term memory consolidation. We trained rats in a spatial discrimination task to retrieve palatable reward in three fixed locations. Hippocampal local field potentials and cortical EEG were recorded for 2 h after each daily training session. There was an increase in ripple density during SWS after early training sessions, in both trained rats and in rats randomly rewarded for exploring the maze. In rats learning the place -reward association, there was a striking further significant increase in ripple density correlated with subsequent improvements in behavioral performance as the rat learned the spatial discrimination aspect of the task. The results corroborate others showing an experience-dependent increase in ripple activity and associated ensemble replay after exploratory activity, but in addition, for the first time, reveal a clear further increase in ripple activity related to associative learning based on spatial discrimination.

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  • After a spatial learning task, increases in ripple density during postlearning sleep were significantly correlated with the formation of associative spatial memories.

    “Similarly, after a spatial learning task, increases in ripple density during postlearning sleep were significantly correlated with the formation of associative spatial memories (955).”

    From About Sleep's Role in Memory (2013) · cites this paper as [955]

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Authors
Ramadan, W., Eschenko, O., & Sara, S. J.
Affiliations
Centre National de la Recherche Scientifique (FR)
Corresponding author
Sara, Susan J.
Venue
PLoS ONE
Published
2009-08-20
Volume
4
Issue
8
Pages
e6697
ISSN
1932-6203 (ISSN-L)
OpenAlex
W2008915709
Cited by
173
References
44
Citations by year
2026: 6 · 2025: 8 · 2024: 10 · 2023: 3 · 2022: 9 · 2021: 4 · 2020: 13 · 2019: 16 · 2018: 12 · 2017: 14 · 2016: 10 · 2015: 10 · 2014: 12 · 2013: 14 · 2012: 6
FWCI
5.02
Type
journal article
Language
en
Open access
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Max Planck Institute for Plasma Physics (submittedVersion)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Memory and Neural Mechanisms
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural dynamics and brain function
Keywords
hippocampal ripples, sharp-wave ripples, slow-wave sleep, memory consolidation, associative memory, spatial discrimination learning, sleep-dependent memory
MeSH terms
Animals, Behavior, Animal, Electroencephalography, Hippocampus, Male, Memory, Sleep, Rats, Sprague-Dawley, Rats

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