SciencePod — Don’t Panic

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this week is some research that delves into the way the human mind deals with fear and panic in survival situations. Probably the most interesting thing was learning how there exist folks who don’t have the capacity to interpret things as fearful! As always, links to articles and the transcript follow the jump.


The link to the original article accessed from the University of Iowa announcement.

How you’re meant to pronounce Urbach-Wiethe disease.

And another study that featured patient ‘SM’ and tested her ability to recognise fear in others.

Transcript — ‘Don’t Panic’

Hello and welcome to another episode of the Tooth Soup Science Pod. My name is Phill English and today, well, today I’m going to take you on a terrifying journey into the dark mechanisms of fear and panic. Just kidding, it’s not going to be as bad as all that. But the article that caught my eye this week does concern the primal instincts of fear that are built into each and every one of us. Or almost every one of us, as you’ll soon find out.

Now, before I make the same mistake as last week and fail to give the researchers proper attribution, let’s do the credits. The research comes from doctors located mainly at the University of Iowa, including senior author John Wemmie and first authors Justin Feinstein and Colin Buzza, and Rene Hurlemann from the University of Bonn. The work has been published in Nature Neuroscience, and for those that aren’t aware, Nature is one of the top two most-cited (and, arguably, most prestigious) journals that a researcher can publish in, the other being Science.

Alright, so the breakthrough concerns which parts of the brains control fear. Up until this study, it was generally accepted that the amygdala was the centre of fear in humans. The amygdala are two small group of nuclei, usually described as almond-shaped, although they look more like macadamias to me. Regardless of which nut they are (or fruit, since almonds aren’t true nuts—there’s a fun fact for you); regardless of that, they have long been known to be related to  the control of long-term memory and emotional reactions, in particular the emotion of fear.

But what happens when someone’s amygdala isn’t functioning properly? Well, as it turns out, you get experimented on. A lot. Loss of amygdala function can happen as a result of the rare condition known as Urbach-Wiethe disease, a genetic disorder that includes symptoms such as a hoarse voice, beaded eye papules, legions, and extensive damage to the amygdala. This disease is pretty rare, so quite a few of the papers I had a look at that explored different aspects of familiarity with fear featured the same initialed patients.

People that have the misfortune to be born with this damage were thought to literally not have the capacity to feel terror. One particular patient, known as ‘SM’ in journal articles, had even earned the moniker of the ‘woman with no fear’. So when the researchers of this study sat SM down and told her that they would be subjecting her and two other amygdala-damaged patients to breathing in carbon dioxide, SM and co. didn’t panic. Just as she hadn’t shown fear when exposed to things like snakes and actually being held up at knife point in real life, SM didn’t show fear as she took the gas mask, breathed deeply of a mix of 35% carbon dioxide…and flipped right out. Her heart rate shot up, she tried to rip the mask off, and she cried for help. A similar reaction was experienced by the other patients, marking the first time they had ever experienced this kind of panic. In contrast to this, 12 people with completely intact amygdalas underwent the same procedure, and only three of the twelve exhibited the same signs of panic. And those three were noted to be quite anxious and panicky even before they put the gas mask on.

So why did the ‘woman with no fear’ and her amygdala-deficient compatriots have this reaction, while 9 out of the 12 with an active ‘fear centre’ get along perfectly fine? Well, it has to do with how our brains process stimuli that has been learned as fear-inducing, versus how it reacts to internal cues that something is wrong with the body.

Fear is, at its base level, a survival mechanism that causes us to respond to a perceived threat by essentially compelling us to run away. In order to utilise this survival mechanism, we must first learn, usually as we grow up, what is and isn’t scary. But patients like SM have never learned that things that are supposed to be scary are in fact scary. If you walked up to an alien and threw a spider at them or showed them a picture of Sara Jessica Parker, they wouldn’t recognise them as things they should avoid. The alien hasn’t had the experience to associate those objects with the emotion of fear. A patient with a damaged amygdala is like those aliens; their capacity to learn what is and isn’t fearful is impaired.

But this research shows that, despite this damage to their capacity to associate fear with external stimuli, they can still get scared and panicky via what the scientists call introceptive threats. Threats such as not being able to breathe—which short-circuit the need for interpretation by the amygdala and instead shoot the body into all-stations panic mode.

Of course, that leaves the question of why the people with intact amygdalas didn’t panic during the carbon dioxide test; whereas you would think that someone with an intact capacity for experiencing fear might do so. The researchers have suggested the reason behind this is that the amygdala not only induces fear, but also controls panic. So it’s kind of like a thermostat of emotions that allows us to recognise dangerous situations but remain calm when panic might overwhelm us and affect our survival chances.

I should take a moment to mention that there is a certain amount of subjectivity to this entire argument. While the physiological responses to the test—the elevated heart rates, clawing at the mask, crying for help, etc—can’t be argued, the naming of the emotion they felt as panic, or fear by the patients is something I’d be interested in discussing with them. How did they know what fear felt like enough to describe it? Was it panic, or just an adrenalin surge? Is it really an emotion if there’s nothing to attach it to externally, or does that make it merely a bodily function? Distinguishing between fear and panic, and making inroads into what fear even is to someone who cannot ordinarily experience it is bordering on the philosophical. And since I’m no philospher, I think I’ll wrap it up there.

But next time you’re watching a scary movie or negotiating the removal of a spider from the lounge room, consider thanking your amygdala: not only for letting you know that there’s a potential threat in front of you, but also potentially for keeping you calm in moments of internal danger.

Thanks for listening, until next week.



photo by: alex_kuehni

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