If I wanted to write about addiction today, my own NPR habit would be an excellent place to begin. News, blogs, radio, podcasts, it’s just so accessible! Today’s entry is not about addiction, but this story does start with “so I was reading NPR News…”
So I was reading NPR News, namely an article titled “What Makes You Feel Fear?” which turned out to be even more intriguing than I expected when I decided to read it. Evidently, researchers have used carbon dioxide inhalation to elicit panic and anxiety in patients with amygdala damage in both hemispheres: patients with no fear centers. How could this be?
This startling discovery comes from a paper published this month in Nature Neuroscience by scientists at the University of Iowa. They tested three patients with Urbach-Wiethe disease (which resulted in bilateral amygdala lesions) by having them inhale CO2. All three experienced panic attacks as a result, and showed significantly increased respiration rates – even with respect to healthy controls. This finding lead the authors to hypothesize that the amygdala may even be able to temporarily inhibit panic, as it has many GABAergic outputs to brainstem regions responsible for panic responses. All of this is pretty stunning. (Of course, the results would have been more stunning if there were a larger group of lesioned patients – all three of them did experience panic attacks in response to the CO2 but so did three of the controls. Fortunately, though, people with bilateral amygdala damage are hard to come by. One could see how a lack of fear could be dangerous!)