Dr. Hammer obtained a PhD in anatomy and conducted post-doctoral studies in neurobiology at UCLA before becoming a Staff Fellow, then Senior Staff Fellow, in the Intramural Research Program at the National Institute of Mental Health in Bethesda, Maryland. In 1984, he became Associate Professor of Anatomy and Pharmacology at the University of Hawaii School of Medicine, where he taught gross anatomy and medical neuroscience, and rose to the rank of Professor in 1993. He received a Research Career Development Award from the National Institute of Neurological Disorders and Stroke in 1987, and was Visiting Associate Research Anatomist at UCLA from 1987 – 1993. In 1994, he moved to Tufts University School of Medicine, where he was Professor of Psychiatry, Anatomy, Pharmacology and Neuroscience, and Director of the Laboratory of Research in Psychiatry. He served as Course Director for Addiction Medicine and Psychopathology courses, taught Medical Neuroscience and Medical Pharmacology, and served as Associate Dean for Educational Affairs at Tufts University School of Medicine from 1998 – 1999. He also held an appointment as Lecturer on Psychiatry at Harvard Medical School, and Visiting Scientist in the Alcohol and Drug Abuse Research Center at McLean Hospital from 1994 – 2006. In 2006, he moved to Phoenix as Professor of Basic Medical Sciences at the University of Arizona College of Medicine.