 On the anatomical level reports vary with certain areas emerging as possibly implicated in PTSD predisposition and pathology. The hippocampus, important in learning and memory, has been shown to be reduced in volume in PTSD patients reviewed by Nutt Malizia, 2004. Two additional regions implicated in PTSD are the amygdale- involved in emotional behavior, and the medial frontal cortex - important in regulation of the HPA axis reviewed by Nutt Malizia, 2004.The major shortcoming of these anatomical studies is their retrospective nature, precluding the possibility of extracting causality. Thus the question of temporal sequence remains to be resolved. 