Impact of cognitive stimulation on ripples within human epileptic and non-epileptic hippocampus


Background: Until now there has been no way of distinguishing between physiological and epileptic hippocampal ripples in intracranial recordings. In the present study we addressed this by investigating the effect of cognitive stimulation on interictal high frequency oscillations in the ripple range (80-250 Hz) within epileptic (EH) and non-epileptic hippocampus (NH). Methods: We analyzed depth EEG recordings in 10 patients with intractable epilepsy, in whom hippocampal activity was recorded initially during quiet wakefulness and subsequently during a simple cognitive task. Using automated detection of ripples based on amplitude of the power envelope, we analyzed ripple rate (RR) in the cognitive and resting period, within EH and NH. Results: Compared to quiet wakefulness we observed a significant reduction of RR during cognitive stimulation in EH, while it remained statistically marginal in NH. Further, we investigated the direct impact of cognitive stimuli on ripples (i.e. immediately post-stimulus), which showed a transient statistically significant suppression of ripples in the first second after stimuli onset in NH only. Conclusion: Our results point to a differential reactivity of ripples within EH and NH to cognitive stimulation.

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Divisions: College of Health & Life Sciences
Additional Information: © 2015 Brázdil et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Uncontrolled Keywords: Epilepsy,High-frequency oscillations,Hippocampal ripples,Human cognition,Neuroscience(all),Cellular and Molecular Neuroscience
Publication ISSN: 1471-2202
Last Modified: 08 Jan 2024 08:30
Date Deposited: 19 Mar 2018 11:55
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://bmcneur ... 2868-015-0184-0 (Publisher URL)
PURE Output Type: Article
Published Date: 2015-07-25
Authors: Brázdil, Milan
Cimbálník, Jan
Roman, Robert
Shaw, Daniel J. (ORCID Profile 0000-0003-1139-8301)
Stead, Matt M.
Daniel, Pavel
Jurák, Pavel
Halámek, Josef



Version: Published Version

License: Creative Commons Attribution

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