WEBVTT - Can You Live Without a Working Amygdala?

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<v Speaker 1>Welcome to brain Stuff. Production of I Heart Radio, Hey

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<v Speaker 1>brain Stuff Lauren vogelbam here. Almost a decade ago, scientists

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<v Speaker 1>introduced the world to patient s M. At first glance,

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<v Speaker 1>the forty four year old mother of three seemed to

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<v Speaker 1>lead a pretty average life, but upon closer observation, she

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<v Speaker 1>exhibited one rare and somewhat troubling characteristic. She had no fear.

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<v Speaker 1>Researchers wrote to provoke fear and SM. We exposed her

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<v Speaker 1>to live steaks and spiders, took her on a tour

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<v Speaker 1>of a haunted house, and showed her emotionally evocative films.

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<v Speaker 1>On no occasion did SM exhibit fear, and she never

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<v Speaker 1>endorsed feeling more than minimal levels of fear. The reason

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<v Speaker 1>s M had lippoid protein osis or werbak Vita syndrome,

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<v Speaker 1>a rare condition that damaged an important structure in her

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<v Speaker 1>brain called the amygdala. But aside from plowing fearlessly through

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<v Speaker 1>some of life's unsettling triggers, SM functioned relatively normally, which

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<v Speaker 1>begs the question can you live without the amygdala? But

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<v Speaker 1>let's back up a tiny step. What is the amygdala?

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<v Speaker 1>Located deep within the brain's temporal lobes. It's an almond

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<v Speaker 1>shaped massive cells or nuclei. That's your amygdala. It's a

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<v Speaker 1>bit misleading to think of the structures one single unit,

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<v Speaker 1>since there are actually two parts to it, each one

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<v Speaker 1>located in opposite hemispheres of the brain, but for general purposes,

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<v Speaker 1>the distinct halves are considered as one part of the

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<v Speaker 1>limbic system, which are the brain structures involved in matters

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<v Speaker 1>of emotions and motivations. The amygdala specifically is associated with

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<v Speaker 1>memory storage and the processing of emotions like anger, pleasure,

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<v Speaker 1>and yep, you guessed it, fear. One major part of

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<v Speaker 1>the amygdala's role is its responsibility in fear conditioning, an

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<v Speaker 1>associative learning process that allows us to learn through repeated

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<v Speaker 1>experience to be scared of something. That learning process happens

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<v Speaker 1>because experiences change our brain circuitry and form new memories.

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<v Speaker 1>This concept was pretty clearly illustrated in experiment which was

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<v Speaker 1>totally unethical by today's standards. Involving an eleven month old

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<v Speaker 1>infant own as a little Albert. Scientists John Watson and

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<v Speaker 1>Rosalie Rayner wanted to see what would happen if they

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<v Speaker 1>paired Albert's perfectly natural fear of loud noises with the

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<v Speaker 1>stimulus he seemed to be pretty neutral about, in this case,

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<v Speaker 1>a white rat. Watson and Rayner allowed Albert to reach

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<v Speaker 1>for the rat, and every time he did, they struck

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<v Speaker 1>a hammer against a steel bar. After sadden repetitions of

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<v Speaker 1>this pairing, Albert started bursting into tears at the very

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<v Speaker 1>sight of the rat. No hammer needed. Because of this

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<v Speaker 1>fear conditioning, his amygdala had linked the disturbing noise with

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<v Speaker 1>the neutral stimulus, and the latter now elicited fear without

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<v Speaker 1>the former. Unfortunately for poor Albert, and again this type

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<v Speaker 1>of experiment would not go down today. The experiment led

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<v Speaker 1>him to develop a generalized fear of things that even

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<v Speaker 1>resembled the white rat, so white coats and white dogs

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<v Speaker 1>would freak him out too. But back to Patient s M.

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<v Speaker 1>On the surface, her fearlessness seems kind of funny, charming.

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<v Speaker 1>Even her kids even got a kick out of it.

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<v Speaker 1>Her eldest son once wrote, me and my brothers see

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<v Speaker 1>the snake on the road. I was like, holy cow,

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<v Speaker 1>that's a big steak. While Mom just ran over there

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<v Speaker 1>and picked it up and brought it out of the

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<v Speaker 1>street and put it in the grass. And let it

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<v Speaker 1>go on its way. She would always tell me how

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<v Speaker 1>she was scared of snakes and stuff like that, but

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<v Speaker 1>then all of a sudden, she's fearless of them. But

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<v Speaker 1>while navigating life without anxiety may seem somewhat exciting and patient,

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<v Speaker 1>SM has made it clear that a person can survive

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<v Speaker 1>perfectly well without an intact amygdala. The absence of natural

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<v Speaker 1>fear can be dangerous, even potentially fatal. A complete lack

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<v Speaker 1>of suspicion or distrust meant SM was vulnerable in many ways. Once,

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<v Speaker 1>while walking through a small park at ten PM, a

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<v Speaker 1>man accosted SM and held a knife to her throat.

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<v Speaker 1>According to researchers quote, in the distance, she could hear

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<v Speaker 1>the church choir singing. She looked at the man and

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<v Speaker 1>confidently replied, if you're going to kill me, you're going

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<v Speaker 1>to have to go through my God's angels first. The

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<v Speaker 1>man suddenly let her go, and if that wasn't strange enough,

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<v Speaker 1>SM didn't flee the scene. She simply walked home. And

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<v Speaker 1>she walked past the same park the next day and

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<v Speaker 1>showed no signs of fear or avoidance. She just didn't

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<v Speaker 1>have it in her. That wasn't the only time SM

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<v Speaker 1>walked right into seriously risky situations and emerged unscathed and unbothered.

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<v Speaker 1>Researchers say she was once physically accosted by a woman

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<v Speaker 1>twice her size, she was nearly killed an act of

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<v Speaker 1>domestic violence, and on more than one occasion, she's been

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<v Speaker 1>explicitly threatened with death. What stands out most is that

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<v Speaker 1>in many of these situations, SM's life was in danger,

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<v Speaker 1>yet her behavior lacked any sense of desperation or urgency.

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<v Speaker 1>But while SM has been held up as the prime

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<v Speaker 1>example of a fearless, amygdala less life, more recent research

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<v Speaker 1>has indicated that the connection between the two characteristics isn't

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<v Speaker 1>so clear. According to a study published in the journal

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<v Speaker 1>Nature Neuroscience, people with damaged amygdala's did still report feelings

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<v Speaker 1>of intense fear, and some even felt more fear than

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<v Speaker 1>those with normally functioning amigdala's. The study looked at participants

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<v Speaker 1>with the same super rare genetic condition that caused SMS

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<v Speaker 1>amygdala damage or about vita disease. Less and three hundred

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<v Speaker 1>people have been found to have it since it was

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<v Speaker 1>discovered in nine nine. Orbak vita disease causes three main

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<v Speaker 1>types of symptoms an extremely hoarse voice, small bumps around

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<v Speaker 1>the eyes, and calcium deposits in the brain. The amygdala

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<v Speaker 1>happens to be the spot in the brain where these

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<v Speaker 1>deposits form. Researchers found that watching horror films did nothing

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<v Speaker 1>to incite fear in participants with this disorder, but they

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<v Speaker 1>were curious whether exposing them to carbon dioxide would induce

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<v Speaker 1>a fear reaction. The amyndella plays a big part in

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<v Speaker 1>detecting carbon dioxide, and when it detects higher concentrations of

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<v Speaker 1>it in the blood, a possible sign that suffocation is occurring.

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<v Speaker 1>It can cause a person to feel panic, contrary to

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<v Speaker 1>what seemed logical. When participants with worbok Vita syndrome breathed

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<v Speaker 1>in air that was thirty five carbon dioxide, they freaked out.

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<v Speaker 1>So what's the deal, a, researchers wrote. Results indicate that

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<v Speaker 1>the amygdala is not required for fear and panic and

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<v Speaker 1>make an important distinction between fear triggered by external threats

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<v Speaker 1>from the environment versus fear triggered internally by carbon dioxide.

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<v Speaker 1>So can you live without the amygdala? Yes? Can you

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<v Speaker 1>live safely and securely without it? Still unclear what scientists

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<v Speaker 1>are working to figure it out. Today's episode was written

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<v Speaker 1>by Michell Konstantinovski and produced by Tyler Clain. Brain Stuff

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<v Speaker 1>is a production of I Heart Radio's How Stuff Works.

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<v Speaker 1>For more in this and lots of other brainy topics,

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