Global and local complexity of intracranial EEG decreases during NREM sleep

Schartner, Michael M, Pigorini, Andrea, Gibbs, Steve A, Arnulfo, Gabriele, Sarasso, Simone, Barnett, Lionel, Nobili, Lino, Massimini, Marcello, Seth, Anil K and Barrett, Adam B (2016) Global and local complexity of intracranial EEG decreases during NREM sleep. Neuroscience of Consciousness, 3 (1). ISSN 2057-2107

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Abstract

Key to understanding the neuronal basis of consciousness is the characterisation of the neural signatures of changes in level of consciousness during sleep. Here we analysed three measures of dynamical complexity on spontaneous depth electrode recordings from 10 epilepsy patients during wakeful rest and different stages of sleep: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability over time of the set of channels active above a threshold; (iii) synchrony coalition entropy, which measures the variability over time of the set of synchronous channels. When computed across sets of channels that are broadly distributed across multiple brain regions, all 3 measures decreased substantially in all participants during early-night non-rapid eye movement (NREM) sleep. This decrease was partially reversed during late-night NREM sleep, while the measures scored similar to wakeful rest during rapid eye movement (REM) sleep. This global pattern was in almost all cases mirrored at the local level by groups of channels located in a single region. In testing for differences between regions, we found elevated signal complexity in the frontal lobe. These differences could not be attributed solely to changes in spectral power between conditions. Our results provide further evidence that the level of consciousness correlates with neural dynamical complexity.

Item Type: Article
Schools and Departments: School of Engineering and Informatics > Informatics
Research Centres and Groups: Sackler Centre for Consciousness Science
Subjects: R Medicine > RC Internal medicine > RC0321 Neurosciences. Biological psychiatry. Neuropsychiatry
Depositing User: Marianne Cole
Date Deposited: 22 Nov 2016 15:32
Last Modified: 12 Sep 2017 03:03
URI: http://sro.sussex.ac.uk/id/eprint/65578

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