It is difficult to find a person who is not afraid of anything. Some are afraid of heights, others are afraid of spiders, others are afraid to ride the elevator … But there are people who are fearless in the truest sense of the word. It's just that the zones of fear in their brains are atrophied. One such patient had to deal with Justin Feinstein of the California Institute of Technology.
The patient, codenamed SM, was diagnosed with Urbach-Withe disease in the mid-1980s. This is a very rare genetic disorder: only about 300 cases of the disease are known worldwide today. Symptoms include skin damage and calcium deposits in the brain. As a result, in this woman, the disease destroyed both amygdala of the brain, which are associated with the emotional sphere. After that, SM completely disappeared from fear, although otherwise her emotions did not undergo any changes.
The woman went to the laboratory of the neurologist Daniel Tranel of the University of Iowa and offered herself as an object for study. She was very interested in researchers, and a number of tests were carried out with her.
It turned out that, oddly enough, a lady who does not feel fear is distinguished by extreme liveliness. For example, one day, scientists invited her to have lunch at a restaurant, where she really liked one waiter. The next day, she again asked to be taken there and was very glad to see her yesterday's acquaintance …
At the same time, SM's social behavior was noticeably out of bounds. For example, she lacked a sense of caution when dealing with strangers. “People who you and I would appear to be shady people, she would call trustworthy,” says Indiana University neuroscientist Daniel Kennedy, who has also been involved in SM research. "She is biased towards people in the sense that she wants to get closer to everyone."
It is curious that the so-called "zone of personal space" (the zone within which a person experiences discomfort from the presence of other people), for this woman was only 0.34 meters, while for others it was almost twice as large. Also, SM could not always read the expressions on the faces of others: she easily determined whether a person was happy or sad, but could not determine the feeling of fear, although it was obvious to others.
Clinical neuropsychologist Justin Feinstein tried to test if something could be scared by the test subject. Horror films did not make any impression on her. In an exotic animal store, she tried to touch the tongue of a snake and pet a tarantula spider. When the researcher took her to the abandoned Waverly Hills TB sanitarium, where there was a "horror attraction" for tourists, the woman only laughed, while other visitors screeched in fear at seeing the "monsters" and hearing the "sounds of the other world." And then … SM scared one of the disguised "monsters" by touching his head out of curiosity.
And yet Feinstein managed to scare the "woman without fear." SM's partners in one experiment were twins AM and BG with identical amygdala lesions. All three were asked to wear masks that were supplied with air containing 35% carbon dioxide. Inhalation of this mixture causes shortness of breath, increased heart rate, increased sweating, dizziness, and about a quarter experience panic.
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Oddly enough, it worked. Moreover, all three experienced a state of panic. SM even waved her hands and, pointing to the mask, shouted: "Help!" When the masks were removed, she explained that she was frightened because she did not understand what was happening to her. The other two subjects reacted similarly.
The result of the experiment, no doubt, should have raised great doubts about the fact that the amygdala is responsible for fear. However, Feinstein suggested that the brain processes "internal" threats in a special way, in particular those associated with suffocation and other physical problems. “This is the primary layer, the basic form of fear,” says the scientist. In his opinion, the high content of carbon dioxide changes the acidity of the blood, and here other centers of the brain are already involved, so that tonsils are not required for the occurrence of panic.
In favor of the "responsibility" of the tonsils is the fact that none of the veterans of the Vietnam War who received traumatic brain injury damage to these parts of the brain (and a total of 200 people with TBI were examined) did not suffer from post-traumatic stress disorder.
From all this, we can conclude that in some situations the absence of a sense of fear may be useful, but in others it deprives a person of the instinct of self-preservation, and he is defenseless in the face of external danger. No wonder the aforementioned SM admitted: "I would not wish this on anyone."
Irina Shlionskaya