John J. Ratey, MD, is an Associate Professor of Psychiatry, Harvard Medical School.  Dr. Ratey has been a leading teacher and researcher on brain and personality and treatment of aggression and the development of disabilities.  He has written extensively on Attention Deficit Disorder, learning disabilities, brain differences that affect social skills and has published 'Shadow Syndromes", a book that has helped broaden our understanding of how the brain affects everyday life.  Dr. Ratey is the author or co-author of more than 60 scientific publications and seven books: Mental Retardation: Developing Pharmacotherapies, The Neuropsychiatry of Personality Disorders, Driven to Distraction, Answers to Distraction, Shadow Syndromes, The User's Guide to the Brain, and Delivered from Distraction.  His latest book is Spark: The Revolutionary New Science of Exercise and the Brain (Little Brown Publishers).