Integrating the Science of Consciousness and Anesthesia

Department of Anesthesia, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Anesthesia and analgesia (Impact Factor: 3.47). 11/2006; 103(4):975-82. DOI: 10.1213/01.ane.0000232442.69757.4a
Source: PubMed


The nature and mechanism of human consciousness is emerging as one of the most important scientific and philosophical questions of the 21st century. Disregarded as a subject of serious inquiry throughout most of the 20th century, it has now regained legitimacy as a scientific endeavor. The investigation of consciousness and the mechanisms of general anesthesia have begun to converge. In the present article I provide an introduction to the study of consciousness, describe the neural correlates of consciousness that may be targets of general anesthetics, and suggest an integrated approach to the science of consciousness and anesthesia.

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    • "Anesthesia is an indispensable stage for doctors during surgery and in the intensive care environment, which enables the patients to undergo surgery to keep unconsciousness and lack of pain through suppressing response of nervous system to nonnoxious stimuli [1] [2] [3]. However, interaction of anesthetic drugs and central nervous system is very complex, so methodologies for assessment of DOA are controversial but very important in medical domain [4] [5] [6]. "
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    ABSTRACT: In order to build a reliable index to monitor the depth of anesthesia (DOA), many algorithms have been proposed in recent years, one of which is sample entropy (SampEn), a commonly used and important tool to measure the regularity of data series. However, SampEn only estimates the complexity of signals on one time scale. In this study, a new approach is introduced using multiscale entropy (MSE) considering the structure information over different time scales. The entropy values over different time scales calculated through MSE are applied as the input data to train an artificial neural network (ANN) model using bispectral index (BIS) or expert assessment of conscious level (EACL) as the target. To test the performance of the new index's sensitivity to artifacts, we compared the results before and after filtration by multivariate empirical mode decomposition (MEMD). The new approach via ANN is utilized in real EEG signals collected from 26 patients before and after filtering by MEMD, respectively; the results show that is a higher correlation between index from the proposed approach and the gold standard compared with SampEn. Moreover, the proposed approach is more structurally robust to noise and artifacts which indicates that it can be used for monitoring the DOA more accurately.
    Computational and Mathematical Methods in Medicine 01/2015; 2015(1). DOI:10.1155/2015/232381 · 0.77 Impact Factor
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    • "Using the systems neuroscience framework to define altered arousal states in terms of behavioral and physiological responses, molecular targets and neural circuits can facilitate cross-disciplinary communication and research on how altered arousal states induced by anesthetic agents relate to the fundamental questions of consciousness (Crick & Koch 2003, Mashour 2006) and how they compare with other altered arousal states such as sleep (Lydic & Baghdoyan 2005, McCarley 2007, Alkire et al. 2008, Franks 2008), sleep aided by pharmacologic agents (NIH Consens. Dev. "
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    ABSTRACT: Placing a patient in a state of general anesthesia is crucial for safely and humanely performing most surgical and many nonsurgical procedures. How anesthetic drugs create the state of general anesthesia is considered a major mystery of modern medicine. Unconsciousness, induced by altered arousal and/or cognition, is perhaps the most fascinating behavioral state of general anesthesia. We perform a systems neuroscience analysis of the altered arousal states induced by five classes of intravenous anesthetics by relating their behavioral and physiological features to the molecular targets and neural circuits at which these drugs are purported to act. The altered states of arousal are sedation-unconsciousness, sedation-analgesia, dissociative anesthesia, pharmacologic non-REM sleep, and neuroleptic anesthesia. Each altered arousal state results from the anesthetic drugs acting at multiple targets in the central nervous system. Our analysis shows that general anesthesia is less mysterious than currently believed.
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    • "Present work has shown a degree of conflicting results. Most previous studies [3,22] indicated that in the sedation level of anesthesia, the neural reactivity of the primary sensory cortices to external stimuli is preserved. Liu and colleagues [23] utilized functional magnetic resonance imaging-guided connectivity analysis to assess the integrity of functional interactions within and between different levels of the task-defined brain regions, and examined how cognitive networks involved in auditory verbal memory are maintained in wakefulness, disrupted in propofol-induced deep sedation, and re-established in recovery. "
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    ABSTRACT: Interaction with the gamma-aminobutyric-acid-type-A (GABAA) receptors is recognized as an important component of the mechanism of propofol, a sedative-hypnotic drug commonly used as anesthetic. However the contribution of GABAA receptors to the central nervous system suppression is still not well understood, especially in the thalamocortical network. In the present study, we investigated if intracerebral injection of bicuculline (a GABAA receptor antagonist) into the thalamus ventral posteromedial nucleus (VPM, a thalamus specific relay nuclei that innervated S1 mostly) could reverse propofol-induced cortical suppression, through recording the changes of both spontaneous and somatosensory neural activities in rat's somatosensory cortex (S1). We found that after injection of bicuculline into VPM, significant increase of neural activities were observed in all bands of local field potentials (total band, 182±6%), while the amplitude of all components in somatosensory evoked potentials were also increased (negative, 121±9% and positive, 124±6%).These data support that the potentiation of GABAA receptor-mediated synaptic inhibition in a thalamic specific relay system seems to play a crucial role in propofol-induced cortical suppression in the somatosensory cortex of rats.
    PLoS ONE 12/2013; 8(12):e82377. DOI:10.1371/journal.pone.0082377 · 3.23 Impact Factor
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