1 00:00:01,920 --> 00:00:06,560 Speaker 1: Welcome to brain Stuff. Production of I Heart Radio, Hey 2 00:00:06,600 --> 00:00:11,000 Speaker 1: brain Stuff Lauren vogelbam here. Almost a decade ago, scientists 3 00:00:11,039 --> 00:00:14,400 Speaker 1: introduced the world to patient s M. At first glance, 4 00:00:14,440 --> 00:00:16,239 Speaker 1: the forty four year old mother of three seemed to 5 00:00:16,280 --> 00:00:19,200 Speaker 1: lead a pretty average life, but upon closer observation, she 6 00:00:19,280 --> 00:00:23,560 Speaker 1: exhibited one rare and somewhat troubling characteristic. She had no fear. 7 00:00:24,200 --> 00:00:27,360 Speaker 1: Researchers wrote to provoke fear and SM. We exposed her 8 00:00:27,360 --> 00:00:29,480 Speaker 1: to live steaks and spiders, took her on a tour 9 00:00:29,520 --> 00:00:32,400 Speaker 1: of a haunted house, and showed her emotionally evocative films. 10 00:00:32,840 --> 00:00:35,720 Speaker 1: On no occasion did SM exhibit fear, and she never 11 00:00:35,800 --> 00:00:40,040 Speaker 1: endorsed feeling more than minimal levels of fear. The reason 12 00:00:40,479 --> 00:00:44,040 Speaker 1: s M had lippoid protein osis or werbak Vita syndrome, 13 00:00:44,240 --> 00:00:46,440 Speaker 1: a rare condition that damaged an important structure in her 14 00:00:46,440 --> 00:00:50,519 Speaker 1: brain called the amygdala. But aside from plowing fearlessly through 15 00:00:50,560 --> 00:00:54,520 Speaker 1: some of life's unsettling triggers, SM functioned relatively normally, which 16 00:00:54,560 --> 00:00:58,880 Speaker 1: begs the question can you live without the amygdala? But 17 00:00:59,040 --> 00:01:01,960 Speaker 1: let's back up a tiny step. What is the amygdala? 18 00:01:02,560 --> 00:01:05,360 Speaker 1: Located deep within the brain's temporal lobes. It's an almond 19 00:01:05,360 --> 00:01:09,840 Speaker 1: shaped massive cells or nuclei. That's your amygdala. It's a 20 00:01:09,840 --> 00:01:12,520 Speaker 1: bit misleading to think of the structures one single unit, 21 00:01:12,560 --> 00:01:14,720 Speaker 1: since there are actually two parts to it, each one 22 00:01:14,760 --> 00:01:18,640 Speaker 1: located in opposite hemispheres of the brain, but for general purposes, 23 00:01:18,760 --> 00:01:21,240 Speaker 1: the distinct halves are considered as one part of the 24 00:01:21,319 --> 00:01:24,639 Speaker 1: limbic system, which are the brain structures involved in matters 25 00:01:24,640 --> 00:01:28,959 Speaker 1: of emotions and motivations. The amygdala specifically is associated with 26 00:01:29,000 --> 00:01:32,720 Speaker 1: memory storage and the processing of emotions like anger, pleasure, 27 00:01:32,920 --> 00:01:37,360 Speaker 1: and yep, you guessed it, fear. One major part of 28 00:01:37,400 --> 00:01:40,800 Speaker 1: the amygdala's role is its responsibility in fear conditioning, an 29 00:01:40,800 --> 00:01:43,720 Speaker 1: associative learning process that allows us to learn through repeated 30 00:01:43,760 --> 00:01:47,600 Speaker 1: experience to be scared of something. That learning process happens 31 00:01:47,600 --> 00:01:51,280 Speaker 1: because experiences change our brain circuitry and form new memories. 32 00:01:52,000 --> 00:01:55,960 Speaker 1: This concept was pretty clearly illustrated in experiment which was 33 00:01:56,000 --> 00:01:59,400 Speaker 1: totally unethical by today's standards. Involving an eleven month old 34 00:01:59,440 --> 00:02:03,800 Speaker 1: infant own as a little Albert. Scientists John Watson and 35 00:02:03,880 --> 00:02:06,280 Speaker 1: Rosalie Rayner wanted to see what would happen if they 36 00:02:06,320 --> 00:02:09,440 Speaker 1: paired Albert's perfectly natural fear of loud noises with the 37 00:02:09,480 --> 00:02:12,800 Speaker 1: stimulus he seemed to be pretty neutral about, in this case, 38 00:02:12,880 --> 00:02:16,560 Speaker 1: a white rat. Watson and Rayner allowed Albert to reach 39 00:02:16,560 --> 00:02:18,959 Speaker 1: for the rat, and every time he did, they struck 40 00:02:18,960 --> 00:02:22,359 Speaker 1: a hammer against a steel bar. After sadden repetitions of 41 00:02:22,400 --> 00:02:25,160 Speaker 1: this pairing, Albert started bursting into tears at the very 42 00:02:25,200 --> 00:02:28,520 Speaker 1: sight of the rat. No hammer needed. Because of this 43 00:02:28,639 --> 00:02:31,800 Speaker 1: fear conditioning, his amygdala had linked the disturbing noise with 44 00:02:31,840 --> 00:02:35,440 Speaker 1: the neutral stimulus, and the latter now elicited fear without 45 00:02:35,480 --> 00:02:39,720 Speaker 1: the former. Unfortunately for poor Albert, and again this type 46 00:02:39,720 --> 00:02:42,920 Speaker 1: of experiment would not go down today. The experiment led 47 00:02:43,000 --> 00:02:45,119 Speaker 1: him to develop a generalized fear of things that even 48 00:02:45,120 --> 00:02:48,040 Speaker 1: resembled the white rat, so white coats and white dogs 49 00:02:48,040 --> 00:02:52,320 Speaker 1: would freak him out too. But back to Patient s M. 50 00:02:52,960 --> 00:02:56,160 Speaker 1: On the surface, her fearlessness seems kind of funny, charming. 51 00:02:56,240 --> 00:02:58,680 Speaker 1: Even her kids even got a kick out of it. 52 00:02:59,200 --> 00:03:01,760 Speaker 1: Her eldest son once wrote, me and my brothers see 53 00:03:01,760 --> 00:03:03,919 Speaker 1: the snake on the road. I was like, holy cow, 54 00:03:04,000 --> 00:03:06,639 Speaker 1: that's a big steak. While Mom just ran over there 55 00:03:06,639 --> 00:03:08,120 Speaker 1: and picked it up and brought it out of the 56 00:03:08,120 --> 00:03:09,600 Speaker 1: street and put it in the grass. And let it 57 00:03:09,600 --> 00:03:11,720 Speaker 1: go on its way. She would always tell me how 58 00:03:11,720 --> 00:03:13,720 Speaker 1: she was scared of snakes and stuff like that, but 59 00:03:13,760 --> 00:03:17,120 Speaker 1: then all of a sudden, she's fearless of them. But 60 00:03:17,360 --> 00:03:21,160 Speaker 1: while navigating life without anxiety may seem somewhat exciting and patient, 61 00:03:21,320 --> 00:03:23,440 Speaker 1: SM has made it clear that a person can survive 62 00:03:23,480 --> 00:03:27,000 Speaker 1: perfectly well without an intact amygdala. The absence of natural 63 00:03:27,040 --> 00:03:31,000 Speaker 1: fear can be dangerous, even potentially fatal. A complete lack 64 00:03:31,000 --> 00:03:35,520 Speaker 1: of suspicion or distrust meant SM was vulnerable in many ways. Once, 65 00:03:35,560 --> 00:03:37,880 Speaker 1: while walking through a small park at ten PM, a 66 00:03:37,880 --> 00:03:40,320 Speaker 1: man accosted SM and held a knife to her throat. 67 00:03:40,840 --> 00:03:43,920 Speaker 1: According to researchers quote, in the distance, she could hear 68 00:03:43,920 --> 00:03:46,240 Speaker 1: the church choir singing. She looked at the man and 69 00:03:46,280 --> 00:03:48,920 Speaker 1: confidently replied, if you're going to kill me, you're going 70 00:03:48,960 --> 00:03:51,400 Speaker 1: to have to go through my God's angels first. The 71 00:03:51,440 --> 00:03:55,160 Speaker 1: man suddenly let her go, and if that wasn't strange enough, 72 00:03:55,320 --> 00:03:58,400 Speaker 1: SM didn't flee the scene. She simply walked home. And 73 00:03:58,440 --> 00:04:00,360 Speaker 1: she walked past the same park the next day and 74 00:04:00,400 --> 00:04:03,240 Speaker 1: showed no signs of fear or avoidance. She just didn't 75 00:04:03,240 --> 00:04:07,080 Speaker 1: have it in her. That wasn't the only time SM 76 00:04:07,120 --> 00:04:11,440 Speaker 1: walked right into seriously risky situations and emerged unscathed and unbothered. 77 00:04:12,280 --> 00:04:15,320 Speaker 1: Researchers say she was once physically accosted by a woman 78 00:04:15,360 --> 00:04:17,760 Speaker 1: twice her size, she was nearly killed an act of 79 00:04:17,800 --> 00:04:20,400 Speaker 1: domestic violence, and on more than one occasion, she's been 80 00:04:20,400 --> 00:04:23,720 Speaker 1: explicitly threatened with death. What stands out most is that 81 00:04:23,760 --> 00:04:26,560 Speaker 1: in many of these situations, SM's life was in danger, 82 00:04:26,800 --> 00:04:31,080 Speaker 1: yet her behavior lacked any sense of desperation or urgency. 83 00:04:31,640 --> 00:04:34,039 Speaker 1: But while SM has been held up as the prime 84 00:04:34,080 --> 00:04:37,880 Speaker 1: example of a fearless, amygdala less life, more recent research 85 00:04:37,880 --> 00:04:40,720 Speaker 1: has indicated that the connection between the two characteristics isn't 86 00:04:40,760 --> 00:04:43,640 Speaker 1: so clear. According to a study published in the journal 87 00:04:43,680 --> 00:04:47,600 Speaker 1: Nature Neuroscience, people with damaged amygdala's did still report feelings 88 00:04:47,640 --> 00:04:50,680 Speaker 1: of intense fear, and some even felt more fear than 89 00:04:50,720 --> 00:04:54,279 Speaker 1: those with normally functioning amigdala's. The study looked at participants 90 00:04:54,279 --> 00:04:56,920 Speaker 1: with the same super rare genetic condition that caused SMS 91 00:04:56,920 --> 00:05:00,559 Speaker 1: amygdala damage or about vita disease. Less and three hundred 92 00:05:00,560 --> 00:05:01,960 Speaker 1: people have been found to have it since it was 93 00:05:02,000 --> 00:05:06,599 Speaker 1: discovered in nine nine. Orbak vita disease causes three main 94 00:05:06,640 --> 00:05:10,520 Speaker 1: types of symptoms an extremely hoarse voice, small bumps around 95 00:05:10,520 --> 00:05:14,080 Speaker 1: the eyes, and calcium deposits in the brain. The amygdala 96 00:05:14,200 --> 00:05:15,880 Speaker 1: happens to be the spot in the brain where these 97 00:05:15,880 --> 00:05:20,240 Speaker 1: deposits form. Researchers found that watching horror films did nothing 98 00:05:20,279 --> 00:05:23,280 Speaker 1: to incite fear in participants with this disorder, but they 99 00:05:23,279 --> 00:05:26,320 Speaker 1: were curious whether exposing them to carbon dioxide would induce 100 00:05:26,360 --> 00:05:29,599 Speaker 1: a fear reaction. The amyndella plays a big part in 101 00:05:29,640 --> 00:05:32,919 Speaker 1: detecting carbon dioxide, and when it detects higher concentrations of 102 00:05:32,920 --> 00:05:35,760 Speaker 1: it in the blood, a possible sign that suffocation is occurring. 103 00:05:36,080 --> 00:05:39,080 Speaker 1: It can cause a person to feel panic, contrary to 104 00:05:39,120 --> 00:05:42,480 Speaker 1: what seemed logical. When participants with worbok Vita syndrome breathed 105 00:05:42,520 --> 00:05:45,960 Speaker 1: in air that was thirty five carbon dioxide, they freaked out. 106 00:05:47,040 --> 00:05:50,960 Speaker 1: So what's the deal, a, researchers wrote. Results indicate that 107 00:05:51,000 --> 00:05:53,839 Speaker 1: the amygdala is not required for fear and panic and 108 00:05:53,880 --> 00:05:57,320 Speaker 1: make an important distinction between fear triggered by external threats 109 00:05:57,320 --> 00:06:01,800 Speaker 1: from the environment versus fear triggered internally by carbon dioxide. 110 00:06:02,760 --> 00:06:06,400 Speaker 1: So can you live without the amygdala? Yes? Can you 111 00:06:06,440 --> 00:06:10,120 Speaker 1: live safely and securely without it? Still unclear what scientists 112 00:06:10,160 --> 00:06:17,560 Speaker 1: are working to figure it out. Today's episode was written 113 00:06:17,560 --> 00:06:20,960 Speaker 1: by Michell Konstantinovski and produced by Tyler Clain. Brain Stuff 114 00:06:21,000 --> 00:06:22,960 Speaker 1: is a production of I Heart Radio's How Stuff Works. 115 00:06:23,200 --> 00:06:25,080 Speaker 1: For more in this and lots of other brainy topics, 116 00:06:25,160 --> 00:06:27,600 Speaker 1: visit our home planet, how stuff Works dot com. And 117 00:06:27,720 --> 00:06:30,000 Speaker 1: for more podcasts for my heart radio, visit thy heart 118 00:06:30,040 --> 00:06:32,520 Speaker 1: radio app, Apple Podcasts, or wherever you listen to your 119 00:06:32,520 --> 00:06:33,200 Speaker 1: favorite shows.