Specific Aim 1: The investigators will test (1) the efficacy of neurofeedback in subjects with PTSD attempting to upregulate ventral medial PFC and simultaneously downregulate amygdala, and (2) determine the number of neurofeedback sessions (dose) needed for target engagement and transfer. Prior to the neurofeedback training, participants' baseline ability to regulate in the absence of neurofeedback from real-time fMRI will be ascertained. Then during session, participants will receive veridical real-time feedback in the scanner indicating the activation level of ventromedial PFC minus amygdala. Participants will attempt to regulate to achieve a predetermined target level known to the participant. Neurofeedback conditions will include (1) false feedback (sham) shows a thermometer that indicates false feedback consisting of noise, (2) view condition shows a thermometer that indicates true activation of ventromedial PFC minus amygdala but the participant is asked not to attempt neuroregulation, (3) free regulate shows a thermometer that indicates true activation of ventromedial PFC minus amygdala while the participant attempts neuroregulation. The investigators will enroll 10 participants who will engage in a six weekly neurofeedback sessions to assess target engagement and dosing.