The document discusses PTSD from a psychophysiological perspective. It describes how exposure to extreme stress can lead to the development of PTSD symptoms. These symptoms involve re-experiencing the traumatic event, avoidance of trauma-related stimuli, and increased arousal. The autonomic nervous system plays an important role in the development and maintenance of PTSD through its influence on emotional and physiological responses to stress. Biofeedback and neurofeedback training methods aim to restore balance and flexibility in the autonomic and central nervous systems to reduce PTSD symptoms. Preliminary data from graded exposure therapy combined with biofeedback shows reductions in arousal and improvements in mood and symptoms.