Speaker 1: Welcome to brain Stuff. Production of I Heart Radio, Hey
Speaker 1: brain Stuff Lauren vogelbam here. Almost a decade ago, scientists
Speaker 1: introduced the world to patient s M. At first glance,
Speaker 1: the forty four year old mother of three seemed to
Speaker 1: lead a pretty average life, but upon closer observation, she
Speaker 1: exhibited one rare and somewhat troubling characteristic. She had no fear.
Speaker 1: Researchers wrote to provoke fear and SM. We exposed her
Speaker 1: to live steaks and spiders, took her on a tour
Speaker 1: of a haunted house, and showed her emotionally evocative films.
Speaker 1: On no occasion did SM exhibit fear, and she never
Speaker 1: endorsed feeling more than minimal levels of fear. The reason
Speaker 1: s M had lippoid protein osis or werbak Vita syndrome,
Speaker 1: a rare condition that damaged an important structure in her
Speaker 1: brain called the amygdala. But aside from plowing fearlessly through
Speaker 1: some of life's unsettling triggers, SM functioned relatively normally, which
Speaker 1: begs the question can you live without the amygdala? But
Speaker 1: let's back up a tiny step. What is the amygdala?
Speaker 1: Located deep within the brain's temporal lobes. It's an almond
Speaker 1: shaped massive cells or nuclei. That's your amygdala. It's a
Speaker 1: bit misleading to think of the structures one single unit,
Speaker 1: since there are actually two parts to it, each one
Speaker 1: located in opposite hemispheres of the brain, but for general purposes,
Speaker 1: the distinct halves are considered as one part of the
Speaker 1: limbic system, which are the brain structures involved in matters
Speaker 1: of emotions and motivations. The amygdala specifically is associated with
Speaker 1: memory storage and the processing of emotions like anger, pleasure,
Speaker 1: and yep, you guessed it, fear. One major part of
Speaker 1: the amygdala's role is its responsibility in fear conditioning, an
Speaker 1: associative learning process that allows us to learn through repeated
Speaker 1: experience to be scared of something. That learning process happens
Speaker 1: because experiences change our brain circuitry and form new memories.
Speaker 1: This concept was pretty clearly illustrated in experiment which was
Speaker 1: totally unethical by today's standards. Involving an eleven month old
Speaker 1: infant own as a little Albert. Scientists John Watson and
Speaker 1: Rosalie Rayner wanted to see what would happen if they
Speaker 1: paired Albert's perfectly natural fear of loud noises with the
Speaker 1: stimulus he seemed to be pretty neutral about, in this case,
Speaker 1: a white rat. Watson and Rayner allowed Albert to reach
Speaker 1: for the rat, and every time he did, they struck
Speaker 1: a hammer against a steel bar. After sadden repetitions of
Speaker 1: this pairing, Albert started bursting into tears at the very
Speaker 1: sight of the rat. No hammer needed. Because of this
Speaker 1: fear conditioning, his amygdala had linked the disturbing noise with
Speaker 1: the neutral stimulus, and the latter now elicited fear without
Speaker 1: the former. Unfortunately for poor Albert, and again this type
Speaker 1: of experiment would not go down today. The experiment led
Speaker 1: him to develop a generalized fear of things that even
Speaker 1: resembled the white rat, so white coats and white dogs
Speaker 1: would freak him out too. But back to Patient s M.
Speaker 1: On the surface, her fearlessness seems kind of funny, charming.
Speaker 1: Even her kids even got a kick out of it.
Speaker 1: Her eldest son once wrote, me and my brothers see
Speaker 1: the snake on the road. I was like, holy cow,
Speaker 1: that's a big steak. While Mom just ran over there
Speaker 1: and picked it up and brought it out of the
Speaker 1: street and put it in the grass. And let it
Speaker 1: go on its way. She would always tell me how
Speaker 1: she was scared of snakes and stuff like that, but
Speaker 1: then all of a sudden, she's fearless of them. But
Speaker 1: while navigating life without anxiety may seem somewhat exciting and patient,
Speaker 1: SM has made it clear that a person can survive
Speaker 1: perfectly well without an intact amygdala. The absence of natural
Speaker 1: fear can be dangerous, even potentially fatal. A complete lack
Speaker 1: of suspicion or distrust meant SM was vulnerable in many ways. Once,
Speaker 1: while walking through a small park at ten PM, a
Speaker 1: man accosted SM and held a knife to her throat.
Speaker 1: According to researchers quote, in the distance, she could hear
Speaker 1: the church choir singing. She looked at the man and
Speaker 1: confidently replied, if you're going to kill me, you're going
Speaker 1: to have to go through my God's angels first. The
Speaker 1: man suddenly let her go, and if that wasn't strange enough,
Speaker 1: SM didn't flee the scene. She simply walked home. And
Speaker 1: she walked past the same park the next day and
Speaker 1: showed no signs of fear or avoidance. She just didn't
Speaker 1: have it in her. That wasn't the only time SM
Speaker 1: walked right into seriously risky situations and emerged unscathed and unbothered.
Speaker 1: Researchers say she was once physically accosted by a woman
Speaker 1: twice her size, she was nearly killed an act of
Speaker 1: domestic violence, and on more than one occasion, she's been
Speaker 1: explicitly threatened with death. What stands out most is that
Speaker 1: in many of these situations, SM's life was in danger,
Speaker 1: yet her behavior lacked any sense of desperation or urgency.
Speaker 1: But while SM has been held up as the prime
Speaker 1: example of a fearless, amygdala less life, more recent research
Speaker 1: has indicated that the connection between the two characteristics isn't
Speaker 1: so clear. According to a study published in the journal
Speaker 1: Nature Neuroscience, people with damaged amygdala's did still report feelings
Speaker 1: of intense fear, and some even felt more fear than
Speaker 1: those with normally functioning amigdala's. The study looked at participants
Speaker 1: with the same super rare genetic condition that caused SMS
Speaker 1: amygdala damage or about vita disease. Less and three hundred
Speaker 1: people have been found to have it since it was
Speaker 1: discovered in nine nine. Orbak vita disease causes three main
Speaker 1: types of symptoms an extremely hoarse voice, small bumps around
Speaker 1: the eyes, and calcium deposits in the brain. The amygdala
Speaker 1: happens to be the spot in the brain where these
Speaker 1: deposits form. Researchers found that watching horror films did nothing
Speaker 1: to incite fear in participants with this disorder, but they
Speaker 1: were curious whether exposing them to carbon dioxide would induce
Speaker 1: a fear reaction. The amyndella plays a big part in
Speaker 1: detecting carbon dioxide, and when it detects higher concentrations of
Speaker 1: it in the blood, a possible sign that suffocation is occurring.
Speaker 1: It can cause a person to feel panic, contrary to
Speaker 1: what seemed logical. When participants with worbok Vita syndrome breathed
Speaker 1: in air that was thirty five carbon dioxide, they freaked out.
Speaker 1: So what's the deal, a, researchers wrote. Results indicate that
Speaker 1: the amygdala is not required for fear and panic and
Speaker 1: make an important distinction between fear triggered by external threats
Speaker 1: from the environment versus fear triggered internally by carbon dioxide.
Speaker 1: So can you live without the amygdala? Yes? Can you
Speaker 1: live safely and securely without it? Still unclear what scientists
Speaker 1: are working to figure it out. Today's episode was written
Speaker 1: by Michell Konstantinovski and produced by Tyler Clain. Brain Stuff
Speaker 1: is a production of I Heart Radio's How Stuff Works.
Speaker 1: For more in this and lots of other brainy topics,
Speaker 1: visit our home planet, how stuff Works dot com. And
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