It is difficult to find anyone who would not fear anything. Some fear heights, others — spiders, others are afraid to ride the elevator … But there are people who are fearless in the truest sense of the word. Just a zone of fear in the brain they are atrophied. On one such patient had to deal with Justin Feinstein of California Institute of Technology.
The patient codenamed SM in the mid 80-ies of the last century was diagnosed with "disease Urbach — Vita". This is a very rare genetic disorder: are today one of the world known only about 300 cases. Among its symptoms — skin damage and deposition of calcium in the brain. As a result of this woman's disease destroyed both the amygdala of the brain that are associated with the emotional sphere. After that, SM completely the feeling of fear, even though the rest of her feelings have not changed.
The woman turned to the laboratory neuroscientist Daniel Trenela from the University of Iowa and offered himself as an object of study. She is very interested in the research, and with it, a series of tests.
It turned out that, oddly enough, the lady felt no fear, characterized by an extremely lively. For example, once the scientists invited her to lunch at a restaurant where she loved the one waiter. The next day, she again asked to take her there too and was very happy when she saw her yesterday's acquaintance …
At the same time, the social behavior of SM significantly beyond the scope. For example, she has no sense of caution in dealing with strangers. "The people that you and I would have seemed shady characters, she would have called you trust — says neuroscientist Daniel Kennedy from Indiana University, who also took part in the research SM. — It discriminates against people in the sense that it wants to be close to all . "
It is interesting that the so-called "zone of personal space" (the area within which a person experiences discomfort from the presence of others), this woman was only 0.34 meters, while the other — almost twice as much. Also SM is not always able to read the expression on the faces of others: it is easily determined, happy or sad people, but could not determine a sense of fear, but for others it was obvious.
Clinical neuropsychologist Justin Feinstein tried to see if you can still something to scare the test. Horror movies no impression on it are not made. The store exotic animals she tried to touch the tongue of a snake and pet tarantula. When the researcher took her to an abandoned sanatorium Waverly Hills, where he worked for tourists' attraction horror, "the woman just laughed, while other visitors screaming with fear when they saw" monsters "and he heard" sounds other world. " And then … SM scared of one of the undercover "monsters" out of curiosity touching his head.
Yet Feinstein managed to scare the "woman with no sense of fear." SM partners in one of the experiments were twins AM and BG with identical injuries amygdala. All three were asked to put on a mask, in which air was supplied with 35 percent carbon dioxide content. Inhalation of this mixture causes shortness of breath, heart palpitations, sweating, dizziness, and about a quarter of experiencing a panic.
Oddly enough, it worked. And the panic experienced all three. SM even waved her hands and pointing to the mask, shouted, "Help!" When the mask was removed, she explained that scared because they do not understand what happens to her. Similarly responded and two other subjects.
The result of the experiment, no doubt, was to cause great doubt in the fact that it is responsible for the fear of the amygdala. Feinstein, however, suggested that the brain processes the special "internal" threats, in particular related to suffocation and other physical problems. "This is the primary layer, the basic form of fear," — said the scientist. According to him, the high content of carbon dioxide changes the acidity of the blood, and are utilized here are other centers of the brain, so that the panic and tonsils are not required.
In favor of the "responsibility" of tonsils is the fact that none of the veterans of the Vietnam War, received as a result of a traumatic brain injury damage to these parts of the brain (and the total number of examined 200 people with TBI), did not suffer from post-traumatic stress disorder.
From all this we can conclude that in some situations, lack of a sense of fear can be helpful, but in others, it deprives a person of the instinct of self-preservation, and he is helpless in the face of external threats. No wonder the aforementioned SM admitted: "I did not want anyone to be such."