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Granger Causality of the Electroencephalogram Reveals Abrupt Global Loss of Cortical Information Flow during Propofol-induced Loss of Responsiveness
- Source :
- Anesthesiology
- Publication Year :
- 2020
- Publisher :
- Lippincott Williams & Wilkins, 2020.
-
Abstract
- Background: It is a commonly held view that information flow between widely separated regions of the cerebral cortex is a necessary component in the generation of wakefulness (also termed “connected” consciousness). This study therefore hypothesized that loss of wakefulness caused by propofol anesthesia should be associated with loss of information flow, as estimated by the effective connectivity in the scalp electroencephalogram (EEG) signal. Methods: Effective connectivity during anesthesia was quantified by applying bivariate Granger to multichannel EEG data recorded from 16 adult subjects undergoing a slow induction of, and emergence from, anesthesia with intravenous propofol. During wakefulness they were conducting various auditory and motor tasks. Functional connectivity using EEG coherence was also estimated. Results: There was an abrupt, substantial, and global decrease in effective connectivity around the point of loss of responsiveness. Recovery of behavioral responsiveness was associated with a comparable recovery in information flow pattern (expressed as normalized values). The median (interquartile range) change was greatest in the delta frequency band: decreasing from 0.15 (0.21) 2 min before loss of behavioral response, to 0.06 (0.04) 2 min after loss of behavioral response (P < 0.001). Regional decreases in information flow were maximal in a posteromedial direction from lateral frontal and prefrontal regions (0.82 [0.24] 2 min before loss of responsiveness, decreasing to 0.17 [0.05] 2 min after), and least for information flow from posterior channels. The widespread decrease in bivariate Granger causality reflects loss of cortical coordination. The relationship between functional connectivity (coherence) and effective connectivity (Granger causality) was inconsistent. Conclusions: Propofol-induced unresponsiveness is marked by a global decrease in information flow, greatest from the lateral frontal and prefrontal brain regions in a posterior and medial direction. Loss of information flow may be a useful measure of connected consciousness.<br />In healthy adult volunteers, propofol anesthesia–induced loss of consciousness was associated with an abrupt, substantial, and global decrease in connectivity. These changes are comparably reversed at regain of consciousness. These observations suggest that information flow is an important indicator of wakefulness. Supplemental Digital Content is available in the text.
- Subjects :
- Adult
Male
Unconsciousness
Bivariate analysis
Electroencephalography
03 medical and health sciences
0302 clinical medicine
Granger causality
Humans
Hypnotics and Sedatives
Medicine
Coherence (signal processing)
Propofol
030304 developmental biology
Cerebral Cortex
0303 health sciences
medicine.diagnostic_test
business.industry
Information flow
Anesthesiology and Pain Medicine
medicine.anatomical_structure
Perioperative Medicine: Clinical Science
Cerebral cortex
Female
Wakefulness
Nerve Net
business
Neuroscience
Anesthetics, Intravenous
Psychomotor Performance
030217 neurology & neurosurgery
medicine.drug
Subjects
Details
- Language :
- English
- ISSN :
- 15281175 and 00033022
- Volume :
- 133
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Anesthesiology
- Accession number :
- edsair.doi.dedup.....0413040db11d563744accc196b59fb0e