Discovering the Brain’s Ghoulish Glitches

17:42 minutes

In this engraving by Martin Joachim Schmidt, a devil sits on a sleeping woman’s stomach. Historically, sufferers of sleep paralysis often claimed it felt like a demon or witch was perched on their chest. Image courtesy of the Wellcome Library, London
In this engraving by Martin Joachim Schmidt, a devil sits on a sleeping woman’s stomach. Historically, sufferers of sleep paralysis often claimed it felt like a demon or witch was perched on their chest. Image courtesy of the Wellcome Library, London

When the brain suffers certain kinds of damage, the results can resemble something out of a B-horror flick. Consider Cotard’s syndrome (sometimes called “walking dead syndrome”), where the sufferer believes—against all available evidence—that they are actually dead. Or how about “alien hand syndrome,” where a patient’s hand goes rogue, acting against its owner’s wishes? Writer Sam Kean joins Ira to talk about the science behind some of the brain’s most ghoulish glitches, and what they can teach us about how healthy brains operate.

Segment Guests

Sam Kean

Sam Kean is a science writer. He’s the author of The Bastard Brigade and Caesar’s Last Breath. He’s based in Washington, D.C.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

The scene, San Francisco, 1978. A young woman senses there’s something not quite right about her boyfriend. A laundromat owner claims his wife isn’t his wife. A woman screams that her husband is not her husband.

BROOKE ADAMS [RECORDING]: People are being duplicated. And once it’s happened to you, you’re part of this thing. It almost happened to me!

IRA FLATOW: That was Brooke Adams in the 1978 remake of the classic flick, Invasion of the Body Snatchers. Alien doubles are good grist for Hollywood. But my next guest says that for sufferers of a rare brain condition, feeling like you’re surrounded by alien doubles can feel all too real. And that’s not the only case where brain biology turns spooky.

Sam Kean is a science writer and author of the book, The Tale of the Dueling Neurosurgeon: The History of the Human Brain as Revealed by True Stories of Trauma, Madness, and Recovery. Sam, welcome back to Science Friday.

SAM KEAN: Hi. Thanks for having me.

IRA FLATOW: Nice to have you. Let’s talk about Invasions of the Body Snatchers. You write that sufferers of something called Cap– was it Capgras?

SAM KEAN: Capgras, I think it is. It’s French.

IRA FLATOW: Capgras Syndrome actually believe their loved ones have been replaced by doubles? Is that right?

SAM KEAN: Yeah. They basically think that everyone in their life around them– especially people they’re very close to– has been taken somehow maybe by aliens, maybe by some nefarious international conspiracy, and replaced with someone who looks exactly the same, has the exact same voice, but isn’t actually that person.

IRA FLATOW: And when you tell them, they just don’t believe you? Or how do they react?

SAM KEAN: Yeah. They basically don’t believe you. I mean, you can explain to them. And sometimes they’ll even agree that no, it really doesn’t make sense that that person would have been kidnapped, or whatever happened to them, murdered or whatever. But still they feel like it must be true. They just at some level will not accept the logic that it doesn’t make any sense.

IRA FLATOW: So what is going on in their brain at this time?

SAM KEAN: It has to do with the way we recognize other human beings. When you see a face, for instance, there’s really two major things going on in your brain. There is conscious recognition where you say, aha. I know who that person is. You realize who the person is.

And then there’s a second system going on beneath that that’s more emotional. It’s sort of that glow that we get when we recognize somebody. It’s happening mostly unconsciously. But it is very important for our recognition of people.

When you look at people who are face-blind for instance, if you show them people– face-blind meaning they basically cannot recognize anyone else. They are just unable to tell individual humans apart. If you show them pictures, though, of some loved one, some friends, and then total strangers, as they flip through the pictures, they won’t recognize anyone consciously. That’s why they’re face-blind.

But if you monitor like their heart rate, other signs of emotional activity, they will still recognize the person on an unconscious level. So they’re still getting that glow for the person.

IRA FLATOW: Hm. Interesting.

SAM KEAN: Yeah. Capgras Syndrome, though, is basically the opposite of that. So these people, because of brain damage usually, they are still getting the conscious recognition. They say, OK. I know that person looks like my mother, looks like my daughter, whatever, but they’re not getting that emotional glow.

In fact, when they look at that person that should be familiar to them, they feel kind of this empty, dead feeling. And that’s very scary to them. They don’t really know what to do. They feel like that person has been taken away from them.

And they feel after that that well, it can’t be really that person. It must be somehow a double. Somehow that person has been replaced in my life.

IRA FLATOW: You write about a woman named Madame M who believed her daughter had been replaced 2,000 times.

SAM KEAN: Yeah. She was really the first well-recognized, well-documented case of Capgras syndrome back in 1918. And yeah, she thought her daughter had been replaced over and over and over again, because every time her daughter changed a little bit, maybe got a haircut, lost a little bit of weight, whatever happened, she would think her daughter was a completely new person.

So she kept thinking her daughter kept getting kidnapped over and over again. She also though her husband was serially kidnapped and replaced as well.

IRA FLATOW: Who needs science fiction when you have this stuff? You know?


IRA FLATOW: Your book starts, as I say, with a horror story that is something that happened to you. You woke up and you weren’t able to move your body.

SAM KEAN: Yeah. It’s a condition called sleep paralysis. And a lot of people actually do experience it, maybe at one point, a couple times in their life. Some of us, unfortunately, experience it on a more regular basis.

And I guess I’m one of the unlucky people. Basically what happens is, your mind wakes up, but your body doesn’t wake up. So you’re sitting there as if you were a statue or something like that. You just cannot move anything in your body, no matter how hard you thy to do it. It’s really kind of an awful condition to be in.

IRA FLATOW: That only happened once to you?

SAM KEAN: No. It happens to me often when I sleep on my back. It happens pretty regularly when I do that, actually.


SAM KEAN: Last week, in fact. Yeah.

IRA FLATOW: You’re not taking any of those sleep medications. I saw one on TV that said that was like a side effect.

SAM KEAN: Oh, yeah. I can believe it too. But no. I don’t take any sort of medications, anything like that. So no. It just happens to me over and over, unfortunately.

IRA FLATOW: Now I hear that one woman with sleep paralysis has been declared dead three times.

SAM KEAN: Yes. A woman in England. She actually woke up in a morgue one time. Because she was that out of it. And it was a problem for her. I think after that they figured out not to keep doing that to her. Checked pretty closely. But it did happen to her.

IRA FLATOW: And some people with sleep paralysis say it’s like a demon sitting on their chest, or even like alien abduction.

SAM KEAN: Yeah. What happens basically in the brain is there’s a structure called the pons that’s in the brain stem. And that helps control the sleep/wake cycle. And it does a couple things.

It sends signals to the higher parts of the brain that might start dreaming going on within your brain. And it also send signals down to the spinal cord. And it basically temporarily paralyzes your muscles.

The reason it does that– sends out chemicals to paralyze your muscles– is that during a nightmare, you don’t want to be jumping up, like taking swings at werewolves or anything like that. It’s good for you that your body can’t move and react to these things going on in your dreams.

But unfortunately, sometimes when you’re trying to wake up, the pons will wake up the higher part of your brain to some degree, but it won’t turn off the chemicals that are still paralyzing your muscles. And that’s what’s basically happening during sleep paralysis.

And unfortunately for some people, it goes even a step further, because their brains don’t shut off the dreams, as well. So they’re awake on some level. Their bodies can’t move. And they have these fantastical things going on in their mind.

And so they interpret them as say, a witch or something squatting on their chest, or aliens might have them strapped down for some reason to examine them. So that’s how their brain makes sense of the experience.

IRA FLATOW: Do you think that some of these real life experiences are the basis for fictional writings or movies or stuff that people will draw from?

SAM KEAN: Yeah. I have seen scientists suggest that they think that some people’s experience, where they really, really feel they were like abducted by aliens or something, it could be a result of this kind of thing happening. So, yeah. It’s definitely possible.

IRA FLATOW: You write about a woman named SM. Why are scientists so fascinated by SM?

SAM KEAN: SM came down with a rare disease that killed all of the cells in her amygdala. The amygdala is a structure in the brain involved with the limbic system. It’s involved in processing emotions, especially fear.

So because she lost her amygdala, her doctor said she has basically two black holes where her amygdala should be. Because she lost her amygdala, she basically hasn’t felt a lick of fear in her life, from the time she was a little girl.

And the studies about her I say are actually kind of a hoot to read about. Because basically the scientists are sitting around thinking up, OK. How can we frighten her? What can we do to try to scare her? You know, let’s drive her to a haunted house. Or I know this exotic pet store that has a bunch of snakes. Let’s drive her there and see what happens.

So basically they just try to think up ever more elaborate ways to frighten her.

IRA FLATOW: And they did eventually find one way.

SAM KEAN: They did find one way. All of the early papers seem to suggest that no matter what they did, they could not induce any sort of fear and panic in her. But pretty recently they tried something a little different. They put a mask over her face that was pumping in air enriched with carbon dioxide. So really, really enriched with carbon dioxide, far more than you would ever encounter in everyday life.

And when you’re suffocating, when you can’t get breaths, a lot of times it’s not the lack of oxygen that’s making you panic, it’s the buildup of carbon dioxide that’s doing it.

So carbon dioxide really, really pushes a lot of really primitive buttons inside of our bodies. But they just assume because she couldn’t feel fear for anything else they tried, that she wouldn’t respond to this carbon dioxide, this enriched air.

But it turns out she did respond to it. In fact, she got really panicked, trying to claw the mask of her face. She was really, really freaked out. And it was the one thing they found that could frighten her.

What they suggested happened, or what is going on in the brain, actually, is that we must have some other sort of independent fear system lurking there that seems to deal with air, and making sure that we get a clear, clean air supply.

And it kind of makes sense on some level, because air is one of those really fundamental things that all living creatures need. They need some sort of gas exchange with the outside world. So you would want some sort of system in your brain that would make sure you’re getting air.

And so they think we actually have two parallel fear systems. One that takes care of most fear, but one that involves mostly just the air that we breathe.

IRA FLATOW: Sort of a backup. So if the main system breaks down, you can still breathe.

SAM KEAN: Yeah. On some level, yeah.

IRA FLATOW: Yeah. And so we learn stuff from these people about how our brains work.

SAM KEAN: Yeah. That’s basically what I was trying to do with the book is try to march around from place to place and show you what happens when each part of the brain shuts down. And unfortunately, a lot of these things end up with these really bizarre consequences about people believing about doubles or all sorts of other unusual things.

IRA FLATOW: Now we’re going to talk more. We’re going to take a short break and come back and talk about more spooky brain biology with author Sam Kean. It’s a great book. It’s The Tale of the Dueling Neurosurgeons: The History of the Human Brain as Revealed by True Stories of Trauma, Madness, and Recovery. Boy, just the right stuff for today.

We’ll take a break and be right back after this.

This is Science Friday. I’m Ira Flatow. If you just joined us, we’re talking this hour about the biology behind some of the brain’s creepiest glitches. Sleep paralysis, alien hand syndrome. My guest is writer Sam Kean, author of The Tale of the Dueling Neurosurgeons.

Let’s see if we have time to get a phone call or two in here. Yeah. Let’s do that. Let’s go to Chandler, Arizona. Yeah. Let’s go to Chandler, Arizona and see if Howard if there. Hi, Howard. Are you there?

HOWARD: Yes. I’m here.

IRA FLATOW: All right. Go ahead.

HOWARD: All right. Thank you for taking my call. I was curious about the sleep paralysis. Is there something of a reversed version of that where your body is not paralyzed during a dream or nightmare?

SAM KEAN: Well, the opposite of sleep paralysis would basically be sleepwalking. So your body is awake and moving, but your mind is still asleep at that point. So yeah. That’s kind of the opposite of it. Sleepwalking.

IRA FLATOW: There’s also something you write about called the Walking Dead syndrome. Dare I ask what that is?

SAM KEAN: So basically these people are convinced that their dead. They are sitting there talking to their doctors. They’re moving. They’re breathing. But they are convinced that they’re dead to the point where some people claim they can smell their own flesh rotting. A few people have apparently tried to cremate themselves. They are absolutely convinced that they are no longer living.

IRA FLATOW: And you can’t put them in a mirror and say, look. You’re here.

SAM KEAN: No. Again, this is one of those things. It’s kind of a theme of the book is that you can explain it to them and be logical about it, but logic just doesn’t penetrate at some point when you’re suffering from a lot of these delusions. It just doesn’t quite get through.

IRA FLATOW: I guess the good news about all these scary things is that they’re very rare, right?

SAM KEAN: They are very rare. Yeah. They are well-established. We know that these things exist. But they are pretty rare conditions.

And usually what has to happen is multiple parts of the brain have to go down at once. It’s not like you get a stroke in some little tiny area, and suddenly this happened. There usually has to be pretty specific and kind of even extensive damage for these things to take place.

IRA FLATOW: Any idea? Why Walking Dead syndrome?

SAM KEAN: That’s one of the ones they don’t quite know what’s going on yet. s theory is, I was talking a little bit before about the emotional glow that we get when we recognize another person. It’s subconscious, but it’s kind of an emotional feeling we have.

Maybe some people think that we probably have this emotional glow when we see ourselves in the mirror or something like that. So maybe these people aren’t feeling that emotional glow for themselves. And they’re interpreting this, for whatever reason, as the fact that they’re dead as a result.

IRA FLATOW: One quick phone call to Ethan in Michigan. Hi, Ethan Welcome to Science Friday.

ETHAN: Hi. So my question was can certain– so I’ve heard of this brain surgery like where they remove half of the brain. It’s kind of lobotomy. Can it cause any of these syndromes?

IRA FLATOW: Hm. Yeah. What about that?

SAM KEAN: Yeah. They do that sometimes with severe epilepsy, usually with very young children, because they will have a chance to recover after that. And things like that do cause– they can cause some anomalies inside the brain. I don’t think it would necessarily cause the kind of things we’re talking about here. But there are other things I talk about in the book that it does affect.

IRA FLATOW: One other thing I want to get to before we have to leave is called alien hand. The alien hand. So it sounds like Dr. Strangelove, you know.

SAM KEAN: Yeah. Basically, they think it might have been that in Dr. Strangelove. Or if you’ve ever seen Addams family, Thing running around, that disembodied hand.

It’s kind of like Thing, except it’s attached to your own body. So your own hand, without your permission, will jump out and grab a pot of boiling water on the stove or grab the steering wheel.

There are cases of one hand trying to button up a shirt, and the other hand coming along right behind it and unbuttoning the shirt. So the hands are either grabbing onto things you don’t want. Or they’re kind of in active opposition to each other.

IRA FLATOW: And we don’t know why that happens?

SAM KEAN: Well, they have a sense. One thing that might be happening is people’s sensory equipment might be getting damaged. So they’re not getting the feedback you normally get that tells your brain oh, I made this movement. So they’re not getting that feedback.

And with the other two types– with the opposition and with the kind of magnetic grasping, there’s probably something a little different going on in the brain. With the hands going in opposition, when say you reach your right hand out to grab an apple or something, your brain is also sending a signal to your left hand saying, OK. You can hang tight for a minute. The right hand has got this.

But if certain parts of the brain get damaged– especially the corpus callosum, which runs down the middle of the brain– that signal might not get to the other hand. And so the other hand thinks, well, I want in on this action. It just sort of jumps out and starts doing it.


SAM KEAN: With the magnetic clasping, what’s probably happening is there’s damage to the frontal part of the brain, which is kind of the executive that kind of tamps down on impulses in the other part of the brain. And when that frontal part gets damaged, your impulse to say, grab a knife or grab a pot of boiling water, it can’t suppress those impulses as well. And so your hand just kind of does what it wants.

IRA FLATOW: Sam Kean. Always, always a pleasure to have you on talking with us. Sam is author of The Tale of the Dueling Neurosurgeons: The History of the Human Brain as Revealed by True Stories of Trauma, Madness, and Recovery. Some of those you heard today.

Thanks again, Sam, for taking time to be with us today.

SAM KEAN: Thank. Happy Halloween.

IRA FLATOW: You too.

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