The amygdala and PTSD

I can hardly bear to watch violent or scary movies. I walked out on The Ring the moment the dried-up little girl was found in the closet (thankfully, the movie was 'showing' at the time in our living room). And the opening scene of The Exorcist in which Father Merrin finds the creepy little statue, the wind blows, and a couple of dogs fight still can interfere with a good night's sleep for me.

Research suggests that an overactive amygdala (the brain's VP in charge of processing emotional experiences and fear) may predict how an individual handles stress, be it in pictures or for real. Israeli scientists used functional magnetic resonance imaging (fMRI) to scan the brains of 18 year old subjects undertaking training as paramedics(1). They scanned the trainee's brains while showing them photographs of graphic medical scenes specifically looking for activation in the amygdala region. They also screened the recruits for stress symptoms including anxiety and insomnia.

After 18 months and a grisly load of combat experience, the researchers found that those paramedics with the largest increases in stress symptoms were the ones with the greatest amygdaloid activity on the initial scan. Study co-author Talma Hendler says that the amygdala may be an "a priori biological marker" for individual susceptibility to post-traumatic stress disorder.

Rather than use a fancy, expensive fMRI as a screening test for fitness under fire, I suggest a less expensive showing of Inglorious Basterds. Check the subjects' heart rate and blood pressure by the movie's end, and you'll know who's ready for the field and who should stick to the office.
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1. Proc Natl Acad Sci USA. 2009 Aug 18;106(33):14120-5.