Traumatic stress has a broad range of effects on the brain. Brain areas implicated in the stress response include the amygdala, the hippocampus, and the prefrontal cortex. Studies in patients who have posttraumatic stress disorder (PTSD) and other psychiatric disorders related to stress have replicated findings in animal studies by finding alterations in these brain areas. Brain regions implicated in PTSD also play an important role in memory function, highlighting the important interplay between memory and the traumatic stress response. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders.