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The Mysteries of Anesthesia

The drugs that put us under for surgery may also help reveal the inner workings of the brain and body.

By Anita Slomski // The MGH Research Issue 2011

Denise Bosco for Proto

How the brain responds to the drugs anesthesiologists use to induce a reversible coma—general anesthesia is not sleep, contrary to the common euphemism—remains a mystery. To study what happens in the brain as people lose consciousness, MGH anesthesiologist Emery Brown uses fMRI to view the changes in neural activity and electroencephalography to measure the electrical activity of neural circuits.

Q: What have you learned about how anesthesia affects the brain?

A: As a person loses consciousness, the patterns of electrical oscillations in various brain regions change as the still-active parts of the brain control other areas. When anesthesia drugs alter frequencies in the brain, they disrupt neural circuits, and the result is unconsciousness.

Q: What are the clinical benefits of knowing this?

A: The reason people have side effects from anesthesia, such as a drop in blood pressure, is because the drugs we use act in areas of the brain where they don’t need to go. Once we understand which areas are relevant to losing consciousness, blocking pain and creating amnesia, we can design more precise ways to get the drugs to those sites only.

Q: According to your latest work, giving Ritalin to rats wakes them up from general anesthesia. How could that be applied to people?

A: After surgery, we let general anesthesia drugs wear off. If we gave patients Ritalin, which activates arousal pathways in the brain, they might regain cognitive function sooner. Ritalin also induces people to breathe more, so it could help patients recover their respiratory function more quickly.

Q: You’ve said that the biggest payoff of your research may be outside your own field. Can you give an example?

A: Ketamine is a drug we use to put people out briefly when they are undergoing a short, painful procedure. Amazingly, it turns out that ketamine also provides almost immediate relief from chronic depression—we’re just not sure why. If we could observe what happens in the brain when we use ketamine for anesthesia, we might be able to solve the mystery.


Video: The Mysteries of Anesthesia


MGH’s Emery Brown explains how anesthesia helps us understand neuroscience.

Understanding Anesthesia

The waning of consciousness during surgery is as mysterious as it is routine. Finally, the curtain may be about to part.

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