In the News
Congratulations to Dr. Andrew Hudson on NIH Grant AwardOctober 3rd, 2016
Nearly 170 years have passed since Ether Day in 1846, when William Morton demonstrated the use of ether as a surgical anesthetic before a rapt audience at the Massachusetts General Hospital.
"But we still don't understand key features of how general anesthetics alter the functional state of the brain, or how the brain finds its way back to its normal functional state after the anesthetic is discontinued," says Andrew Hudson, MD, PhD.
We may be a step closer to achieving that understanding since Dr. Hudson has received a prestigious grant from the National Institute of General Medical Sciences for mentored research. The NIH K08 grant will support four years of protected time for Dr. Hudson to study the impact of anesthetics on the intact nervous system, with the longer term goal of understanding how shifts in neuronal circuit properties lead to recovery of consciousness from anesthesia.
Dr. Hudson's interest in the "really big, open question" of consciousness developed early in his career as an undergraduate at the University of California at Berkeley. He became interested in the broad fields of cognitive science, artificial intelligence, philosophy, and linguistics, and how they are linked.
As a medical student and graduate student in neurophysiology at Cornell, Dr. Hudson had the opportunity to meet Fred Plum, MD, a renowned neurologist who helped to develop the Glasgow Coma Scale and co-authored the classic text, The Diagnosis of Stupor and Coma. A summer course at the Marine Biological Laboratory in Woods Hole, MA, introduced Dr. Hudson to the work of Emery Brown, MD, PhD, an anesthesiologist and statistician at Harvard who studies the neuroscience of how anesthetics act in the brain. Those experiences cemented Dr. Hudson's interest in neural substrates of consciousness.
Using a mouse model, Dr. Hudson is investigating whether individual neuron populations within the brain cortex have different susceptibilities to inhaled anesthetics. Because different populations of interneurons have unique expression profiles, including neurotransmitter receptors and ion channels, Dr. Hudson says, "It is reasonable to assume that they have different sensitivities to anesthetics."
Dr. Hudson uses a bright green fluorescent protein to monitor activity in a population of neurons. Specifically, he is looking at three subtypes of inhibitory interneurons, which he thinks are likely to be differentially susceptible to anesthetics. Each different population of neurons has changes in spontaneous electrical activity at different anesthetic depths, and his research model causes them to fluoresce when they are stimulated.
By selectively targeting and intervening in these neuron populations, he hopes to move from a descriptive account of what happens to them to "a causal investigation of the changes in the brain that lead to unconsciousness from anesthesia and the resulting recovery of consciousness after anesthesia." Dr. Hudson's work is the first demonstration of a selective effect of anesthetics on a particular neuronal subpopulation within a cortical network, and may explain why characteristic EEG shifts occur at different levels of anesthesia.
Dr. Hudson's research mentors at UCLA are Joshua Trachtenberg, PhD, Professor of Neurobiology, and Aman Mahajan, MD, PhD, Chair of the Department of Anesthesiology and Perioperative Medicine.
A mouse model isn't ideal for studying human responses to anesthesia, according to Dr. Hudson, since the thalamus plays a much bigger role in consciousness in humans. "But it's a place to start," he says.
Karen Sibert, MD
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