THE ALTERED TRAIT SPECTRUM Altered traits map along a spectrum starting at the negative end, with post-traumatic stress disorder (PTSD) as a case in point. The amygdala acts as the neural radar for threat. Overwhelming trauma resets to a hair trigger the amygdala’s threshold for hijacking the rest of the brain to respond to what it perceives as an emergency.17 In people with PTSD, any cue that reminds them of the traumatic experience—and that for someone else would not be particularly noticeable—sets off a cascade of neural overreactions that create the flashbacks, sleeplessness, irritability,
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