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Decoding The Void

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In the days before anesthesia, surgery was about the worst ordeal you could endure. Patrick Purdon, Assistant Professor of Anesthesia at Harvard Medical School, gives producer Tim Howard a tour of Mass General Hospital’s famous Ether Dome, an operating theater that would have resonated with the screams of patients on a daily basis in the early 1800s. Writer Julie Fenster introduces us to a con artist-turned-dentist named William Morton, the man who would become famous in 1846 (if undeservedly, as contemporaries would claim) for the discovery of painless surgery.

With the discovery of anesthesia, however, came a strange new problem: nobody was quite sure what was happening when the brain slipped from consciousness into this new, drugged state. We meet Carl Zimmer, whose own experience with anesthesia leads him to wonder how it’s possible that time seems to simply disappear when you go under. What happens in that invisible moment? And why is it that some patients remain conscious, even when they appear to be knocked out?

Patrick Purdon tries to answer this question in an experiment that takes the induction of anesthesia and slows it down to a crawl while analyzing the brain’s electrical activity. With the help of his colleague Emery Brown, Professor of Anesthesia at Harvard Medical School, Patrick explains the strange electrical signature they discovered, and why it just may be that sought-after indicator of when a brain is truly, totally, definitely unconscious.



Emery Brown, Julie Fenster, Patrick Purdon and Carl Zimmer

Produced by:

Tim Howard

Comments [15]

Susan Smythe from Swarthmore

I have had many surgeries - have often wondered where I went - this is fascinating.

Sep. 03 2017 03:19 PM
artis from Port Townsend

I've been wanting to get back at these guys for 50 years.
When I was 10 years-old, 1958/59 I had 3 surgical operations at the Naval hospital in Bremerton, WA.
The 3 operations were; a tonsillectomy (which was bungled and 3 days later, at home, I hemorrhaged blood through my nose and mouth - that is another story); and two operations for an orchidectomy (look it up), it pertains to testicles. For each of the 3 operations ether was used as an anesthetic. Each time was horrible. Horrible hallucinations.The surgeons looked like monsters with green, ugly, warted faces, speaking in horror movie drawl.
The third time, as they were wheeling me to OR, having already administered a sedative, I asked if they were going to use ether again. Their answers were; " . . .just relax, everything will be (or 'is') just fine.
When I was on the table and they put the screen over my mouth I >>Bolted<<.
In your article you mentioned some adult having to be held down by six men. I was (at ten mind you) held down by one adult on each arm, each leg, my head, while being administered this freak'n poison.
There are some odors in social environment that resemble ether. It freaks me everytime I smell it.
Sorry, I just had to get that out. Thank you for the article and the program.

Sep. 02 2017 05:02 PM
David from Denver

This was a really great segment - I was just given a link to it and must have missed it when it first was broadcast. As an anesthesiologist (and former faculty at MGH- Emery Brown was one of my residents years ago!) I think it is the best explanation I have heard about the cutting edge of thinking about anesthetic mechanisms. Very well done!

For Caitlin B's inquiry: the reference can be found at but it is not an easy paper for the non-scientist, or even the non-specialist. Perhaps more understandable for the layman is the editorial on this important paper, in the same issue of PNAS, accessible here:

Jun. 17 2015 03:54 PM
Me from here

It is intriguing how this substance manipulates your brain chemistries; slowing time down internally even though the external existence of time is in sync with the present moment. Very cool

Sep. 06 2014 09:25 PM

"I am Sleeping" is by Roomful of teeth - Ansa Ya Skip to 3:29

The full clip is heard on this episode. Sadly,there is nothing more.

Sep. 04 2014 08:32 PM

One of my favorite stories yet guys. I just learned that we have a local production of the events here:

Jul. 31 2014 12:38 PM
Josh D

The song is called Roomful of Teeth by Ansa Ya

Jun. 07 2014 05:11 PM

Most interested in the bit around 12:50 the moment of loss of consciousness. I had nose surgery 27 March 2014 and later I was surprised at how fast I lost consciousness after receiving anesthesia. I knew as I was waking up everything was over and many hours had passed even though it seems that I had just shut my eyes. The loss of consciousness wasn't gradual, it was sudden. It took 6 1/2 hours. In the months following, during my recovery, I also began to think of death. At the end, will it be similar to the loss of consciousness or will there be a tunnel with a light at the end as is so often described?

Jun. 01 2014 08:39 PM
Eliza from Minnasota

I had my tonsils taken out last year and I loved learning about anesthesia. I remember the family life nurse telling me about the IV and the room I would wake up in. They used air pressure to put the IV in and then I woke up in a room felling all tingly. It took about five seconds before I realized it was over.

May. 31 2014 03:28 PM

where do you find the music that was in the beginning, is there a credit area? when she is singing "I am sleepy".... I loved that!

Mar. 23 2014 07:08 PM
Blake from Rochester, Minnesota

Local anesthetics are much better understood. Most function by blocking the signals from your nerve endings to your brain. Your brain still functions, but it cannot receive the input from the senses that have been blocked (pain). This is typically done (in drugs that end in "caine" like lidocaine or bupivacaine) by blocking sodium channels from inside the cell. These channels are responsible for continuing the signal down axons (they are kinda like the wires of your body).

Feb. 27 2014 04:55 PM
Caitlin B

This is fascinating stuff, I'd be curious to know the name and journal of the paper I assume Purdon and Brown published so I could learn more!

Feb. 25 2014 05:50 PM
Chris P. from Chico, CA

After listening to this episode (yet another fascinating topic!), and the description of what happens in the brain during unconsciousness, I found myself wondering about local anesthetics. They must work in a completely different way, since they only affect an area of nerve endings. Is that process any better understood?

Feb. 04 2014 01:57 AM
Adam from Boston, MA

I'd just like to point out that the man contemporaries credit for inventing anesthesia, is Dr. Crawfrod Long who first used it in 1842.

Jan. 24 2014 02:35 PM
Garrek from Osaka, Japan

This was a really cool episode. It would be cool if you guys followed up on more consciousness research in future episodes!

Jan. 24 2014 01:54 AM

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