Tracking Brain States under General Anesthesia by Using Global Coherence Analysis
Author(s)
Pierce, Eric T.; Walsh, John L.; Harrell, P. Grace; Tavares-Stoeckel, Casie; Habeeb, Kathleen; Cimenser, Aylin; Purdon, Patrick Lee; Salazar-Gomez, Andres F.; Brown, Emery N.; ... Show more Show less
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Time and frequency domain analyses of scalp EEG recordings are widely used to track changes in brain states under general anesthesia. Although these analyses have suggested that different spatial patterns are associated with changes in the state of general anesthesia, the extent to which these patterns are spatially coordinated has not been systematically characterized. Global coherence, the ratio of the largest eigenvalue to the sum of the eigenvalues of the cross-spectral matrix at a given frequency and time, has been used to analyze the spatiotemporal dynamics of multivariate time-series. Using 64-lead EEG recorded from human subjects receiving computer-controlled infusions of the anesthetic propofol, we used surface Laplacian referencing combined with spectral and global coherence analyses to track the spatiotemporal dynamics of the brain's anesthetic state. During unconsciousness the spectrograms in the frontal leads showed increasing α (8–12 Hz) and δ power (0–4 Hz) and in the occipital leads δ power greater than α power. The global coherence detected strong coordinated α activity in the occipital leads in the awake state that shifted to the frontal leads during unconsciousness. It revealed a lack of coordinated δ activity during both the awake and unconscious states. Although strong frontal power during general anesthesia-induced unconsciousness—termed anteriorization—is well known, its possible association with strong α range global coherence suggests highly coordinated spatial activity. Our findings suggest that combined spectral and global coherence analyses may offer a new approach to tracking brain states under general anesthesia.
Date issued
2011-05Department
Harvard University--MIT Division of Health Sciences and Technology; Massachusetts Institute of Technology. Department of Brain and Cognitive SciencesJournal
Proceedings of the National Academy of Sciences of the United States of America
Publisher
National Academy of Sciences
Citation
Cimenser, A. et al. “Tracking brain states under general anesthesia by using global coherence analysis.” Proceedings of the National Academy of Sciences 108 (2011): 8832-8837. Web. 2 Dec. 2011. © 2011 New York Academy of Sciences
Version: Final published version
ISSN
0027-8424
1091-6490