Difference maps (PTSD minus healthy controls) of cortical activity following aversive (upper panel) and pleasant picture presentation (lower panel). The right panel indicates statistically significant brain regions revealed by permutation statistics. Cortical activity following neutral picture presentation was used for normalization. We found significantly reduced activity following aversive picture presentation in the left occipital cortex in PTSD patients compared to healthy controls. No differences of the cortical activation were found between healthy controls and PTSD subjects in following pleasant pictures.