For Combat Veterans Suffering from Post-Traumatic Stress Disorder, 'Fear Circuitry' in the Brain Never Rests

"Chronic trauma can inflict lasting damage to brain regions associated with fear and anxiety. Previous imaging studies of people with post-traumatic stress disorder, or PTSD, have shown that these brain regions can over-or under-react in response to stressful tasks, such as recalling a traumatic event or reacting to a photo of a threatening face. Now, researchers at NYU School of Medicine have explored for the first time what happens in the brains of combat veterans with PTSD in the absence of external triggers...."

http://www.sciencedaily.com/releases/2013/05/130518153257.htm

Another article on this study

http://psychcentral.com/news/2013/05/20/even-without-stress-ptsd-effects-persist-in-brain-regions/55057.html