Neuroimaging studies in post-traumatic stress disorder (PTSD) have revealed changes in brain structure and function that may underlie the symptoms of PTSD. Two brain areas that have been consistently implicated in PTSD include the hippocampus and prefrontal cortex. Several studies showed that PTSD is associated with reduction in volume of the hippocampus, a brain area involved in learning and memory, as measured with magnetic resonance imaging (MRI). Positron emission tomography (PET) studies showed dysfunction of medial and orbital prefrontal cortex during PTSD symptom provocation and in response to traumatic reminders. Decreased benzodiazepine receptor binding was found in the medial prefrontal cortex as measured with neuroimaging in PTSD. The hippocampus and medial prefrontal cortex play important roles in memory and emotional regulation, and dysfunction in these areas may underlie memory deficits and pathological emotions in PTSD.