Hayes JP, et al. - This research aimed to investigate the hypothesis that volume of the dentate gyrus, a region putatively involved in the distinctive encoding of similar events, was smaller in people with posttraumatic stress disorder (PTSD) versus trauma-exposed controls. The findings demonstrated that dentate gyrus abnormalities were related to symptoms of PTSD. Although additional evidence is needed to determine whether these abnormalities underlie fear generalization and other memory alterations in PTSD.