Cortical Disintegration Mechanism of Anesthetic-Induced Unconsciousness

Chapter
Part of the Contemporary Clinical Neuroscience book series (CCNE)

Abstract

The fundamental thesis of this paper is that under general anesthesia, the brain preserves its reactivity to sensory stimulation, but the information conveyed by these stimuli is not integrated – therefore, it is not consciously perceived. This happens at anesthetic depths associated with behavioral unresponsiveness from which unconsciousness is inferred. A further hypothesis is that general anesthetic agents interfere with the integration of sensory information encoded in cortical neuronal activity in the gamma frequency band. A critical region whose connectivity with the rest of the brain may be disrupted in anesthesia is the posterior parietal association cortex. While it is true that most anesthetic agents utilize different cellular and molecular pathways and neuron groups to produce their pharmacological effects, a common systems level action that may lead to unconsciousness by all anesthetics is the disruption of cortical information processing. The plausibility of these hypotheses and supporting experimental evidence is discussed in the context of theoretical considerations for defining consciousness and inferring the presence or absence of consciousness in an anesthetized subject.

Keywords

Consciousness gamma oscillations neuronal synchrony visual evoked response information exchange entropy neuronal networks functional connectivity 

Notes

Disclosure Statement

This work was supported by the grant R01 GM-56398 from the Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland, USA. This work was not an industry-supported study and the author has no financial conflicts of interest. The comments of Drs. Zeljko Bosnjak, Quinn Hogan, Thomas Stekiel, and Anna Stadnicka to this manuscript are appreciated. The contribution of graduate students Jeannette Vizuete and Sivesh Pillay to the experiments from which results are presented here is appreciated.

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© Humana Press, a part of Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Department of AnesthesiologyMedical College of WisconsinMilwaukeeUSA

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