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Author Notes:

Correspondence: Jamie W. Sleigh, Peter Rothwell Academic Centre, Waikato Hospital, Pembroke Street, Private Bag 3200, Hamilton 3240, New Zealand e-mail: jamie.sleigh@waikatodhb.health.nz

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Research Funding:

This project has been funded in whole or in part with funds from the James S. McDonnell Foundation under Grant Award No. 220020346.

This work was partially supported by a U.S. National Science Foundation Graduate Research Fellowship (to VMD) and in part by the National Science Foundation through the research grant CMMI 1031811 (to AJS).


  • connection strength
  • emergence
  • general anesthesia
  • resting membrane conductivity
  • sleep-manifold

Emergence from general anesthesia and the sleep-manifold


Journal Title:

Frontiers in Systems Neuroscience


Volume 8, Number AUG


, Pages 146-146

Type of Work:

Article | Final Publisher PDF


The electroencephalogram (EEG) during the re-establishment of consciousness after general anesthesia and surgery varies starkly between patients. Can the EEG during this emergence period provide a means of estimating the underlying biological processes underpinning the return of consciousness? Can we use a model to infer these biological processes from the EEG patterns? A frontal EEG was recorded from 84 patients. Ten patients were chosen for state-space analysis. Five showed archetypal emergences; which consisted of a progressive decrease in alpha power and increase peak alpha frequency before return of responsiveness. The five non-archetypal emergences showed almost no spectral EEG changes (even as the volatile general anesthetic decreased) and then an abrupt return of responsiveness. We used Bayesian methods to estimate the likelihood of an EEG pattern corresponding to the position of the patient on a 2-dimensional manifold in a state space of excitatory connection strength vs. change in intrinsic resting neuronal membrane conductivity. We could thus visualize the trajectory of each patient in the state-space during their emergence period. The patients who followed an archetypal emergence displayed a very consistent pattern; consisting of progressive increase in conductivity, and a temporary period of increased connection strength before return of responsiveness. The non-archetypal emergence trajectories remained fixed in a region of phase space characterized by a relatively high conductivity and low connection strength throughout emergence. This unexpected progressive increase in conductivity during archetypal emergence may be due to an abating of the surgical stimulus during this period. Periods of high connection strength could represent forays into dissociated consciousness, but the model suggests all patients reposition near the fold in the state space to take advantage of bi-stable cortical dynamics before transitioning to consciousness.

Copyright information:

© 2014 Hight, Dadok, Szeri, García, Voss and Sleigh.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/).

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