International Anesthesiology Clinics
January 1, 2007
G. Mashour
13 citations
The development of anesthesia in the mid-19th century transformed surgery from a desperate, agonizing ordeal into a controlled, humane procedure. This historical account traces the early use of ether and chloroform, highlighting key figures such as William T.G. Morton and John Snow, and the rapid adoption of anesthesia in both America and Europe. It describes the initial skepticism and ethical debates surrounding pain relief, as well as the profound impact on surgical practice, patient outcomes, and the professionalization of anesthesiology. The narrative also examines the social and cultural shifts that accompanied the acceptance of anesthesia, including changes in patient expectations and the role of the anesthesiologist.
Nature Communications
January 5, 2023
Zirui Huang, G. Mashour, A. Hudetz
Dimensions of consciousness such as wakefulness and awareness are encoded in multiple neurofunctional dimensions of the brain's cortical geometry. Disruptions of consciousness from pharmacological, neuropathological, or psychiatric causes degrade one or more major cortical gradients depending on the condition. Network-specific reconfigurations within this multidimensional gradient space are associated with behavioral unresponsiveness across various etiologies, and these spatial reconfigurations correlate with a temporal disruption of structured transitions of dynamic brain states. The work provides a unifying neurofunctional framework for multiple dimensions of human consciousness in both health and disease.
Anesthesiology
February 26, 2021
D. Pal, G. Mashour
Cortical acetylcholine concentration tracks with the capacity for conscious experience: high during wakefulness, low during slow-wave sleep, and high again during REM sleep when dreaming occurs. General anesthetics produce parallel changes—GABAergic drugs like propofol and sevoflurane lower acetylcholine and reduce the probability of experience, while non-GABAergic drugs like ketamine and nitrous oxide raise acetylcholine and increase the likelihood of dreams or hallucinations. Interventions that raise brain acetylcholine reverse anesthetic traits or reduce potency in humans and rodents, whereas lesions of cholinergic neurons in the basal forebrain reduce anesthetic requirements for isoflurane and propofol.
Science Advances
March 1, 2020
Zirui Huang, Jun Zhang, Jinsong Wu et al.
Consciousness depends on frequent access between two key brain networks: the default mode network and the dorsal attention network, which normally alternate their activity in an anticorrelated manner. A 'temporal circuit' of dynamic brain activity trajectories regulates transitions between these networks. Balanced reciprocal accessibility of brain states within this circuit characterizes consciousness, while isolation of the networks from the temporal circuit is associated with unresponsiveness from various causes. These findings advance understanding of how anticorrelated brain systems support consciousness.
NeuroImage
March 1, 2019
Heonsoo Lee, D. Golkowski, D. Jordan et al.
Large-scale brain networks function near a critical state, and partial phase locking—a network science concept—shapes the characteristic functional connectivity and asymmetric anterior-posterior phase lag entropy (PLE) topography at this critical state, with low PLE for high-degree nodes and high PLE for low-degree nodes. Comparing PLE topography at criticality with electroencephalogram data from baseline consciousness, isoflurane anesthesia, ketamine anesthesia, vegetative state/unresponsive wakefulness syndrome, and minimally conscious state shows that topographical similarity and strength of PLE differentiate these pharmacologic and pathologic states of consciousness. This provides a theory-based metric to quantify how far a perturbed brain network deviates from criticality, rather than merely determining critical or non-critical state.
Frontiers in Human Neuroscience
February 16, 2018
Hyoungkyu Kim, A. Hudetz, Joseph Lee et al.
A practical method estimates integrated information (Φ), a measure proposed by integrated information theory to be related to consciousness, from 128-channel EEG. The method alone cannot distinguish certain anesthetic states, but combining Φ with four EEG connectivity parameters—power, frequency, functional connectivity, and modularity—differentiates all states of consciousness. The association of Φ with EEG connectivity during anesthesia offers a new approach to applying the theory, potentially useful for characterizing consciousness in sleep, anesthesia, and coma.