Deciphering the Dynamics of the Unconscious Brain Under General Anesthesia
Emery Brown
August 25, 2021, Wednesday, 3:00 PM - 4:00 PM EDT
General anesthesia is a drug-induced, reversible condition comprised of five behavioral states: unconsciousness, amnesia (loss of memory), antinociception (loss of pain sensation), akinesia (immobility), and hemodynamic stability with control of the stress response. Our work shows that a primary mechanism through which anesthetics create these altered states of arousal is by initiating and maintaining highly structured oscillations. These oscillations impair communication among brain regions. We illustrate this effect by presenting findings from our human studies of general anesthesia using high-density EEG recordings and intracranial recordings. These studies have allowed us to give a detailed characterization of the neurophysiology of loss and recovery of consciousness due to propofol. We show how these dynamics change systematically with different anesthetic classes and with age. As a consequence, we have developed a principled, neuroscience-based paradigm for using the EEG to monitor the brain states of patients receiving general anesthesia. We demonstrate that the state of general anesthesia can be rapidly reversed by activating specific brain circuits. Finally, we demonstrate that the state of general anesthesia can be controlled using closed loop feedback control systems. The success of our research has depended critically on tight coupling of experiments, signal processing research and mathematical modeling.
Emery N. Brown, M.D., Ph.D. is the Warren M. Zapol Professor of Anaesthesia at Harvard Medical School; an anesthesiologist at Massachusetts General Hospital (MGH); and the Edward Hood Taplin Professor of Medical Engineering and Computational Neuroscience at MIT. He received his B.A. in Applied Mathematics (magna cum laude) from Harvard College, his M.A. and Ph.D. in statistics from Harvard University and his M.D. (magna cum laude) from Harvard Medical School. Dr. Brown completed his internship in internal medicine at the Brigham and Women's Hospital and his residency in anesthesiology at MGH. He joined the faculty at MGH and Harvard Medical School in 1992 and the faculty at MIT in 2005. Dr. Brown is an anesthesiologist-statistician whose research is defining the neuroscience of how anesthetics produce general anesthesia. He also develops statistical methods for neuroscience data analysis. Dr. Brown has received an NIH Director's Pioneer Award, the Sacks Prize from the National Institute of Statistical Science, the American Society of Anesthesiologists Excellence in Research Award, the Dickson Prize in Science, the Swartz Prize for Computational and Theoretical Neuroscience, and a Doctor of Science Honoris Causa from the University of Southern California. He is a fellow of the American Academy of Arts Sciences and the U.S. National Academy of Inventors. Dr. Brown is a member of the U. S. National Academy of Medicine, National Academy of Sciences and the National Academy of Engineering. Dr. Brown is the first African American, the first statistician and the first anesthesiologist to be elected to all three National Academies.