SM has a rare condition called Urbach-Wiethe disease. It's known to cause calcium deposits in the brain, and in her case, those deposits have damaged her amygdala, effectively eliminating her fear response. Researchers have exposed her to many stimuli that other people would find frightening, but that SM responds to with curiosity. Unsurprisingly, her lack of fear has exposed her to dangerous situations throughout her life—she's responded coolly to being held at knifepoint and gunpoint.
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Key Facts In This Video
"SM" is the codename for a woman whose amygdala has been damaged, eliminating her ability to feel fear. 00:11
SM exhibited no fear when researchers took her through a haunted house attraction. 00:59
Though she doesn't feel fear, SM is not emotionless. 01:27