Global and local complexity of intracranial EEG decreases during NREM sleep
Michael Schartner, Andrea Pigorini, Steve A. Gibbs, Gabriele Arnulfo, Simone Sarasso, Lionel Barnett, Lino Nobili, Marcello Massimini, Anil K. Seth, Adam B. Barrett
Neuroscience of Consciousness January 27, 2017 DOI: 10.1093/nc/niw022 via OpenAlex
Summary
AI-generated from the abstractDuring non-rapid eye movement (NREM) sleep, neural dynamical complexity—measured by Lempel-Ziv complexity, amplitude coalition entropy, and synchrony coalition entropy—decreased substantially across broadly distributed brain regions in ten epilepsy patients. This decrease partially reversed during late-night NREM sleep and returned to wakeful rest levels during rapid eye movement (REM) sleep. Local brain regions mirrored this global pattern. The frontal lobe showed elevated signal complexity. These changes were not solely due to spectral power differences. The findings suggest that level of consciousness correlates with neural dynamical complexity.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 10 |
| Population | Epilepsy patients |
| Keywords | Eye movement Psychology Electroencephalography K-complex Consciousness |
| Citations | 158 |
| Key finding | Neural dynamical complexity decreases during early-night NREM sleep and partially reverses during late-night NREM sleep, returning to wakeful rest levels during REM sleep. |
Abstract
Key to understanding the neuronal basis of consciousness is the characterization 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 (WR) 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 three 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 WR 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.