RecruitingDevice studyTranscutaneous Vagal Nerve Stimulation in Veterans With Posttraumatic Stress DisorderThis study effects the effects of transcutaneous cervical vagal nerve stimulation (tcVNS) or a sham control on brain, physiology, and PTSD symptoms in Veterans with posttraumatic stress disorder (PTSD). Veterans undergo brain imaging and physiological measures in conjunction with traumatic scripts before and after three months of twice daily treatment with tcVNS or sham stimulation at home.