The Neurophysiology of Anesthesia: Q&A with Emery Brown, MD, PhD

Emery Brown, MD, PhD, asserts that the future of anesthesiology lies in neuroscience—a perspective that has driven and shaped his career—and one that he is putting into practice as part of a new joint research center between Massachusetts General Hospital and the Massachusetts Institute of Technology.

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As an anesthesiologist, statistician and director of the Neuroscience Statistics Research Laboratory at Mass General, Dr. Brown is world-renowned for his work in advancing neuroscience data analysis and characterizing the neurophysiology of anesthesia-induced altered states of arousal.

"Anesthesiologists know how to administer anesthetics to a point of unconsciousness," says Dr. Brown. "But we have not yet taken a neuroscientific approach to understand how to make delivery of the anesthetics more precise in order to achieve an appropriate state of anesthesia without overdosing or underdosing the patient. Doing so would open doors for advances in both clinical anesthesia and neuroscience."

The joint center will focus on studying the neurophysiology of anesthesia to create new approaches in anesthesiology and the treatment of common neuropsychiatric disorders such as insomnia, depression, and coma recovery. Below, Dr. Brown shares more about his vision for the center and for the field of anesthesiology as a whole.

Q. What has your research already revealed about the neuroscience of anesthesia?

We know a lot more now about the basic neurophysiology of anesthesia—how the anesthetics are working in the brain, why they produce unconsciousness, how the drugs interfere with the brain's ability to communicate, and the post-operative impact. Essentially, anesthetics produce unconsciousness by slowing down or speeding up the brain's oscillatory activity, thereby making it difficult for regions of the brain to communicate normally.

Armed with this understanding, we can leverage and interpret electroencephalogram (EEG) recorded during a patient's surgical procedure to measure the changing dynamics in the brain and ensure that the patient is receiving the amount of anesthesia needed to be adequately anesthetized.

Q. What advances are you aiming to develop through the new Mass General/MIT center?

There is so much research opportunity in the field of anesthesia. The fundamental technique of how the anesthetic state is generated is essentially the same as what it was in 1846 when the first successful public demonstration of the use of ether for surgical anesthesia was performed at Mass General. The widely used anesthetic sevoflurane is an ether. If we make neuroscience an integral part of anesthesiology training and practice, our focus will shift from predominantly studying the pharmacology of anesthetics to understanding the neurophysiology of how the drugs alter the brain's behavior.

In my collaboration with Mass General and MIT, my team and I will focus on studying the various aspects of the basic neurophysiology of anesthesia. Our goals will be to make wider use of the EEG to monitor anesthetic state, develop more precise approaches to create and control the state of anesthesia, and develop ways to wake the brain up after anesthesia. Our focus is to translate basic science advances into clinical advances.

This research has implications for many other advances, such as minimizing brain dysfunction and side effects after surgery, a problem that is particularly prevalent amongst older patients. After surgery, the expectation is that patients wake up on their own and resume normal mental activity as though they never had been under anesthesia. However, anesthesia can commonly lead to side effects like nausea, vomiting, and grogginess. How can we help turn the brain circuits back on after anesthesia, as opposed to just letting patients wake up on their own? Are there ways to choose which brain regions and circuits we activate and inactivate through anesthesia rather than having to influence all of them?

My research aims to answer this and many other questions as a way to create new therapies to produce sedation and better ways to control the brain's arousal level.

Q. Can these advances extend beyond anesthesia?

Anesthesia essentially turns off the brain and the nervous system, thus putting a person into a state where they can tolerate a very traumatic intervention. Suppose you can achieve this in a more physiologically sound way that produces a true restful state—could this help us to improve treatment for sleep disorders that currently rely on medications that produce sedation rather than sleep with the hope that natural sleep mechanisms will take over? Or suppose we develop ways to wake someone from anesthesia so that they feel good and are clear-headed. Could this improve the treatment of depression or how we wake up people who have intact brain circuits from comas?

There is great potential for all of this to be true. These are clinical neuroscience questions that are ripe for study in our new center.

Learn more about Mass General Neuroscience

Learn more about Anesthesia Research