SM was born in 1965 and suffered from acute epileptic seizures from an early age. It was initially thought that he had a brain tumor causing the epilepsy. However, the medical team confirmed that the seizures were caused by bilateral atrophy within the medial temporal lobe of the amygdala.
The most striking thing about SM is that it did not recognize fear. To create it, researchers exposed it to live snakes and spiders, took it on a tour of a haunted house, and showed it horror movies. When SM was asked to draw fear, it drew a crawling baby. The study was conducted and published in 2010. This study revealed fear in the brain.
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Emotions
Patient SM suffered from Urbach-Wiethe, a strange disease that, among other things, caused calcium deposits to form in the amygdala, with subsequent damage to the cells that make up this brain structure. SM’s neuropsychological examination revealed that his intelligence was within normal limits, that various cognitive functions were preserved, and that there were no motor, sensory, or perceptual problems.
The main impairment observed in the patient was in the processing of emotional information. SM showed no difficulty in judging the emotions expressed on the faces of different people from photographs, unless it was fear. He seemed unable to recognize and understand the fear response when looking at others. I did not recognize it in other people’s faces.
However, from a theoretical point of view, SM was able to describe situations that could cause fear in people, and was also able to verbally use different concepts to describe it.
SM also failed to convey this emotion through his drawings. When asked to draw the face of a person experiencing fear, he drew a figurine of a baby on all fours. In contrast, he had no difficulty drawing the face of a person experiencing a different emotion.
Snakes, spiders, horror stories and haunted houses
In a study published in December 2010, Feinstein, Adolphs, Damasio, and Tranel attempted to induce fear in SM by exposing her to live snakes and spiders (stimuli that typically induce fear in humans and primates) at an exotic pet store and took her to a supposed hospital having enjoyed and forced him to watch emotionally evocative horror films. In none of the above mentioned instances did he show the slightest hint of fear.
SM said that she hated snakes and spiders and tried to avoid them, but upon entering the store, she was spontaneously attracted and fascinated by the large collection of snakes. An employee asked her if she would like to hold a snake, and she agreed. SM showed great interest and curiosity in the animal, repeatedly commenting, “That’s cool!” and asking numerous questions of the store employee (e.g., “What do they see when they look at you?”). He also showed a compulsive desire to “touch” the larger, more dangerous snakes in the store.
Haunted building
Investigators took CM to the Waverly Hills Sanitarium, a former hospital located in Louisville, Kentucky, considered one of the most haunted places in the United States. Paranormal enthusiasts describe ghostly apparitions and unexplained sounds, and say that the fifth floor of Waverly Hills, known as “Death Row,” is particularly active in terms of paranormal activity. Terminally ill patients were housed on this floor, and legends suggest that many of them died there.
Upon arrival, SM and the research team were paired with a group of five women (all strangers). From the start, SM eagerly led the entire group through the abandoned hospital, showing no signs of hesitation when turning corners or entering dark corridors. As the rest of the group lagged behind, she repeatedly called out, “This way, guys, follow me!” In addition to her apparent lack of fear, SM demonstrated an unusual willingness to explore the place, as well as a high level of excitement and enthusiasm.
Horror
Finally, the researchers used a selection of films that evoked fear and other types of emotions, including disgust, anger, sadness, happiness, and surprise. When watching non-scary films, SM experienced high levels of the emotions evoked by each film. In contrast, he did not show a fear response. However, she noted that most people would probably be frightened by the content of such films even if she had not. This demonstrates that his poor experience of fear cannot be entirely explained by a deficit in its recognition and understanding.
Although SM’s life story is full of traumatic events, he never showed any signs of fear in any of them.
The Importance of the Amygdala
During this study, the area of the brain responsible for fear was discovered, the same one that was damaged by SM.
The amygdala constantly monitors the information we receive from our environment for signs of danger. The nervous system registers stimuli of biological significance, such as snakes or spiders, because these animals were a threat to our ancestors. So it has evolved to allow us to recognize them, which helps us survive. However, the amygdala is also activated by positive stimuli that are important to the individual. This is done based on previous experience.
Thus, thanks to the mechanisms of emotional memory that depend on the amygdala, some stimuli are unimportant for some people, but are of fundamental importance for others.
The case of patient CM showed the importance of the amygdala in recognizing fearful facial expressions. However, various studies that have followed this clinical case over the years have shown the contribution that the amygdala can make in other, more complex aspects, such as attention or social cognition.
By understanding how the brain processes fear in cases like SM, we can find treatments that will prevent fear from taking over our lives.