Dr. Timothy D. Sheehan, M.D., is a retired US Army psychiatrist. He served in a wide variety of clinical and leadership positions during thirty-one years of active duty followed by over fourteen ye...view moreDr. Timothy D. Sheehan, M.D., is a retired US Army psychiatrist. He served in a wide variety of clinical and leadership positions during thirty-one years of active duty followed by over fourteen years as an army civilian psychiatrist. His interest in complex systems has contributed significantly to his understanding of brain function.view less