title: Preferential inhibition of frontal-to-parietal feedback connectivity is a neurophysiologic correlate of general anesthesia in surgical patients.
abstract: BACKGROUND
  The precise mechanism and optimal measure of anesthetic-induced unconsciousness has yet to be elucidated. Preferential inhibition of feedback connectivity from frontal to parietal brain networks is one potential neurophysiologic correlate, but has only been demonstrated in animals or under limited conditions in healthy volunteers.
  
  
  RESULTS
  We recruited eighteen patients presenting for surgery under general anesthesia; electroencephalography of the frontal and parietal regions was acquired during (i) baseline consciousness, (ii) anesthetic induction with propofol or sevoflurane, (iii) general anesthesia, (iv) recovery of consciousness, and (v) post-recovery states. We used two measures of effective connectivity, evolutional map approach and symbolic transfer entropy, to analyze causal interactions of the frontal and parietal regions. The dominant feedback connectivity of the baseline conscious state was inhibited after anesthetic induction and during general anesthesia, resulting in reduced asymmetry of feedback and feedforward connections in the frontoparietal network. Dominant feedback connectivity returned when patients recovered from anesthesia. Both analytic techniques and both classes of anesthetics demonstrated similar results in this heterogeneous population of surgical patients.
  
  
  CONCLUSIONS
  The disruption of dominant feedback connectivity in the frontoparietal network is a common neurophysiologic correlate of general anesthesia across two anesthetic classes and two analytic measures. This study represents a key translational step from the underlying cognitive neuroscience of consciousness to more sophisticated monitoring of anesthetic effects in human surgical patients.
authors: Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors: Seung-Woo
authors: SW
authors: Ku
authors: UnCheol
authors: U
authors: Lee
authors: Gyu-Jeong
authors: GJ
authors: Noh
authors: In-Gu
authors: IG
authors: Jun
authors: George A
authors: GA
authors: Mashour
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D000771:Anesthesia, Intravenous; D018681:Anesthetics, General / Q000494:pharmacology; D003243:Consciousness / Q000187:drug effects / Q000502:physiology; D004569:Electroencephalography; D025461:Feedback, Physiological / Q000187:drug effects* / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000187:drug effects* / Q000502:physiology*; D013502:General Surgery; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000187:drug effects* / Q000502:physiology*
chemical_list: D018681:Anesthetics, General