An electrophysiological marker of arousal level in humans
Abstract
Deep non-rapid eye movement sleep (NREM) and general anesthesia with propofol are prominent states of reduced arousal linked to the occurrence of synchronized oscillations in the electroencephalogram (EEG). Although rapid eye movement (REM) sleep is also associated with diminished arousal levels, it is characterized by a desynchronized, 'wake-like' EEG. This observation implies that reduced arousal states are not necessarily only defined by synchronous oscillatory activity. Using intracranial and surface EEG recordings in four independent data sets, we demonstrate that the 1/f spectral slope of the electrophysiological power spectrum, which reflects the non-oscillatory, scale-free component of neural activity, delineates wakefulness from propofol anesthesia, NREM and REM sleep. Critically, the spectral slope discriminates wakefulness from REM sleep solely based on the neurophysiological brain state. Taken together, our findings describe a common electrophysiological marker that tracks states of reduced arousal, including different sleep stages as well as anesthesia in humans.
Data availability
Source data files have been updated and are provided here:Lendner, Janna (2020), An Electrophysiological Marker of Arousal Level in Humans, UC Berkeley, Dataset, https://doi.org/10.6078/D1NX1V
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An Electrophysiological Marker of Arousal Level in HumansDryad Digital Repository, doi:10.6078/D1NX1V.
Article and author information
Author details
Funding
Deutsche Forschungsgemeinschaft (LE 3863/2-1)
- Janna Desiree Lendner
National Institute of Neurological Disorders and Stroke (R37NS21135)
- Robert T Knight
Deutsche Forschungsgemeinschaft (HE 8329/2-1)
- Randolph F Helfrich
National Institute of Mental Health (R01AG03116408)
- Matthew P Walker
National Institute of Mental Health (RF1AG05401901)
- Matthew P Walker
National Institute of Mental Health (RF1AG05410601)
- Matthew P Walker
National Institute of Mental Health (F32-AG039170)
- Bryce A Mander
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: We collected four independent datasets for this study to assess the neurophysiological basis of states of reduced arousal, namely sleep and general anesthesia.Study 1 - Anesthesia scalp EEG: All participants were informed and provided written consent in accordance with the local ethics committee (Regional Committees for Medical and Health Research Ethics in Oslo case number 2012/2015 and extension 2012/2015-8).Study 2 - Anesthesia intracranial EEG: All participants were informed and provided written consent in accordance with the local ethics committee (Regional Committees for Medical and Health Research Ethics in Oslo case number 2012/2015 and extension 2012/2015-8).Study 3 - Sleep scalp EEG: All participants were informed and provided written consent in accordance with the local ethics committee (Berkeley Committee for Protection of Human Subjects Protocol Number 2010-01-595).Study 4 - Sleep intracranial EEG: All patients provided informed consent according to the local ethics committees of the University of California at Berkeley and at Irvine (University of California at Berkeley Committee for the Protection of Human Subjects Protocol Number 2010-01-520; University of California at Irvine Institutional Review Board Protocol Number 2014-1522, UCB relies on UCI Reliance Number 1817) and gave their written consent before data collection.
Copyright
© 2020, Lendner et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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