Researchers at the National Institutes of Health and the National Naval Medical Center suggest that drugs or pacemaker-like devices aimed at dampening activity in those brain regions might be effective treatments for PTSD.

Jordan Grafman, of the NIH's National Institute of Neurological Disorders and Stroke, and colleagues, studied 193 veterans registered with Vietnam Head Injury Study and 52 veterans with combat exposure but no head injury.

The participants were classified as either having developed PTSD at some point in their lifetime or having never developed PTSD. Computerized tomography, or CT, scans were used to map the brain injuries.

By comparing the distribution of brain injuries between the two groups, the researchers found two regions where damage was rarely associated with PTSD: the amygdala and the ventromedial prefrontal cortex.

The study, published in Nature Neuroscience, found PTSD occurred in 18 percent of subjects with damage to the ventromedial prefrontal cortex and zero subjects with damage to the amygdala.