People with a rare brain disorder don’t get scared — except when they breathe carbon dioxide
Not all fear is the same. A woman who laughs at horror movies, grabs dangerous snakes and calmly deals with knife-wielding men nonetheless surrenders to terror at a single puff of suffocating carbon dioxide.
This woman, known as SM, has a disease that damaged her amygdala, a brain structure implicated in fear. But the new results involving her and two others with the same disease, published online February 3 in Nature Neuroscience, show that a certain kind of danger signal can bypass the amygdala, hitting the panic button in other parts of the brain.
The need to breathe is one of the most fundamental requirements for survival. Clinical neuropsychologist Justin Feinstein of the University of Iowa in Iowa City believes that the instinct to get air might tap into a brain system that’s more primal than the amygdala.