Credit Bryce Vickmark for The New York Times

Dr. Emery Neal Brown, 54,  is a professor of anesthesiology at Harvard Medical School, a professor of computational neuroscience at M.I.T. and  a practicing physician, seeing patients at Massachusetts General Hospital. Between all that, he heads a laboratory seeking to unravel one of medicine&#8217;s big questions: how anesthesia works.

We spoke for three hours last month at his Massachusetts General office and more recently by telephone. An edited version of the two interviews follows.

Q. Anesthesia — what drew you to it?

A. I enjoyed my anesthesia rotation at medical school. I could see that it was very fast-paced and that you had to make important decisions quickly. That appealed. Plus: the regular hours. I saw myself doing research, as well as working with patients. You need a predictable schedule — which anesthesiologists have — to manage both.

It’s also a very important piece of modern medicine. If you think about what occurs when we do surgery, it’s a very traumatic insult to the body. You’re cutting people open, removing organs or possibly even transplanting them. The anesthesiologist puts people into a condition where they can tolerate such extreme assaults.

Q. Is anesthesia like a coma?

A. It’s a reversible drug-induced coma, to simplify. As with a coma that’s the result of a brain injury, the patient is unconscious, insensitive to pain, cannot move or remember. However, with anesthesia, once the drugs wear off, the coma wears off.

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Q. Anesthesia was first demonstrated right here at Massachusetts General Hospital in 1846. Does that historical fact drive your research?

A. I think about it a lot. Seriously!

There’s quite a story to how that first public demonstration happened. Apparently, there was a social practice in that era called “ether follies.” People got together and they sniffed ether. At one of these, someone fell and cut himself, but felt no pain. And the story got out, which led a Boston dentist to start experimenting with ether for painless oral surgery. He brought the idea to the great surgeon John Collins Warren, and together they used it in an operation here to remove a neck tumor. “Gentlemen, this is no humbug,” Dr. Warren declared after the successful procedure, meaning that this was the real thing and that it was going to change medicine. Before that, surgery was mostly butchery. The most successful surgeon was the one who could lop off a limb quickest. To this day, most inhaled anesthetics are ether. They’ve been embellished a bit, but they are basically ether.

Q. Is it true that we don’t really know how anesthesia works?

A. It’s viewed as a mystery, and that’s wrong. It’s not a black box. There’s a lot that is actually known, and more is developing as neuroscience moves forward. We’ve certainly known how to make anesthesia safe. We watch the patient while he or she is “under.” We know what’s normal in terms of heart rate, blood pressure, temperature, gases, etc. If things start to deviate from that, we intervene. We’ve gotten very far by creating high standards for care while under anesthesia.

Q. In your research, you’ve been trying to figure out how anesthesia actually works. How do you go about doing that?

A. Since 2004, we’ve been taking volunteers and giving them anesthesia, though not in the midst of actual surgeries.

As our subjects go under, we image their brains in functional M.R.I. scanners and measure brain activities with EEG monitors. Before this technology was available, researchers had only looked at what happened to patients before and after anesthesia. But with today’s functional M.R.I., we can watch people lose consciousness — see how the various parts of the brain change in activity. We can watch the transitions, what parts of the brain are turned on and off.

Q. Were there ethical problems in designing a study where you rendered your subjects unconscious?

A. Absolutely. Because some people felt, “This is anesthesia! You should only administer it when people need surgery.” Believe me: our study got more scrutiny than any other at this hospital.

The way we overcame potential objections was by recruiting a unique set of study subjects. They were patients who’d already had tracheostomies — surgical holes in their throat. We could place a tube into the hole and connect it to a breathing circuit. If anyone got into trouble while in the scanner, we’d immediately be able to help them breathe.

Q. Was there resistance to your doing the study?

A. There’s a large body of people in my field who feel that very little more progress needs to made because the process works well enough. My answer is that we could improve anesthesia tremendously if we knew more neuroscience. This is a golden moment in neuroscience, and anesthesiologists — who, after all, work with the brain every day — ought to be part of it. Instead, people ignore what’s happening over there and go, “It’s never been solved, people have been working on this since 1846, it’s fine as is, why bother?” There’s a strange compliancy.

Q. What has your research shown so far?

A. Under general anesthesia, the brain is not entirely shut down. Certain parts are turned off; others are quite active — not only “active,” but there is a level of activity that is quite regular.

Our observation is that it is this regular activity prevents the brain from transmitting information and contributes to a state of unconsciousness. It’s analogous to stopping communication down a phone line when transmission is blocked. You could block transmission another way: by sending a loud signal down the line so that that signal was the only thing you hear. So in some parts what we see is that activity is turned off, leading to unconsciousness. In other parts, we see activity that is more active than normal. This also leads to unconsciousness. In sum: the drugs alter the way the brain transmits information.

Q. Some years ago when I had an operation, I remember the anesthesiologist trying to soothe me by saying that she was going to put me “to sleep.” Was this right?

A. No. And I wish we’d refrain from saying that to patients. It’s inaccurate. It would be better if we explained exactly what the state of general anesthesia is and why it’s needed. Patients appreciate this intellectual honesty. Moreover, anesthesiologists should never say “put you to sleep” because it is exactly the expression used when speaking about euthanizing an animal!

Q. Why would someone like Michael Jackson take the anesthetic Propofol for insomnia?

A. I can only conjecture. But that incident is another reason why I think we need to be more precise describing what we do. If an anesthesiologist says, “We’re going to have you go to sleep,” some might think you could use these drugs for sleep. The bottom line is that when you’re undergoing anesthesia, you’re in a state akin to a coma. That always needs to be remembered.

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