Abstract
This review describes structural and functional neuroimaging studies of posttraumatic stress disorder (PTSD). First, a combined structural MRI, diffusion tensor imaging, and event-related potential study in victims of Tokyo sub- way sarin attack revealed left anterior cingulate cortex (ACC) volume reduction which was tightly coupled with P300 amplitude reduction, and aberrant anterior cingulum integrity in PTSD patients. In a monozygotic twin study of US combat veterans, we found a significant volume reduction in the hippocampus in both combat-exposed PTSD subjects and their co-twins compared with both combat-exposed non-PTSD subjects and their co-twins. These results suggest that cortical abnormalities in PTSD may be characterized by those in limbic regions and medial prefrontal cortex that regulate the limbic regions. These abnormalities may at least in part represent pre-existing vulnerability to PTSD. Characterizing gene-environment interaction in the formation of medial prefrontal and limbic abnormalities will be important to uncover brain mechanisms for stress vulnerability and anxiety and depression spectrum disorders. Neuroimaging will be also a powerful tool for clinical application such as diagnosis and objective monitoring of treatment response in stress related disorders.
