By | Michelle Konstantinovsky | health.howstuffworks.com
Almost a decade ago, scientists introduced the world to Patient SM. At first glance, the 44-year-old mother of three seemed to lead a pretty average life, but upon closer observation, she exhibited one rare and somewhat troubling characteristic: She had no fear. “To provoke fear in SM, we exposed her to live snakes and spiders, took her on a tour of a haunted house, and showed her emotionally evocative films,” researchers wrote. “On no occasion did SM exhibit fear, and she never endorsed feeling more than minimal levels of fear.”
The reason? SM had lipoid proteinosis or Urbach-Wiethe, a rare condition that damaged an important structure in her brain called the amygdala. But aside from plowing fearlessly through some of life’s unsettling triggers, SM functioned relatively normally, which begs the question…can you live without the amygdala?
What Is the Amygdala?
Located deep within the brain’s temporal lobes sits an almond-shaped mass of cells (or nuclei) — that’s your amygdala. It’s a bit misleading to think of the structure as one single unit since there are actually two parts to it, each one located in a different brain hemisphere. But for general purposes, the distinct halves are considered as one part of the limbic system, the brain structures involved in matters of emotions and motivations. The amygdala specifically is associated with memory storage and the processing of emotions like anger, pleasure and — yup, you guessed it — fear.
One major part of the amygdala’s role is its responsibility in “fear conditioning,” an associative learning process that allows us to learn through repeated experience to be scared of something. That learning process happens because experiences change brain circuits and form new memories. This concept was pretty clearly illustrated in a (totally unethical by today’s standards) 1920 experiment involving an 11-month infant known as Little Albert.