In 1973 Dr. Thatcher was appointed as Assistant Professor of Psychiatry at New York Medical College and in 1977 as an Associate Professor of Psychiatry at New York University School of Medicine. In 1979 Dr. Thatcher was appointed as a professor of Psychiatry and Director of the QEEG service at Shock Trauma, University of Maryland before joining the National Institutes of Health in 1991 as the Program Manager for the integration of 128 channel EEG with MRI, PET and SPECT.

Dr. Thatcher was the director of the NeuroImaging Laboratory at the Bay Pines VA Medical Center, Bay Pines, FL from 1993 to May 2006 and he is currently the director of Neuroimaging at the Applied Neuroscience Research Institute in Bay Pines, Florida. Dr. Thatcher is an adjunct professor of Neurology in the Department of Neurology at the University of South Florida. As the principal investigator for the Department of Defense Head Injury Program (DVHIP) Dr. Thatcher over saw the collection and analysis of quantitative EEG from over 1,500 head injured patients which also involved the integration of EEG with MRI.

Dr. Thatcher currently serves on the National Institutes of Health Scientific Advisory Committee for the NIH Human Brain Map Project and he sits on the boards of the American Board of Electroencephalography and Clinical Neurophysiology and the EEG and Clinical Neuroscience Society. Dr. Thatcher is certified as an expert in both conventional electroencephalography and quantitative electroencephalography (QEEG). Dr. Thatcher is the author of six books and over 200 publications.