Mark S. George, M.D., was among the first to use functional brain imaging (positron emission tomography, [PET] or functional magnetic resonance imaging [fMRI]) to understand brain changes that occur in depression and mania. This imaging work directly led to his pioneering use of a non-invasive brain stimulation method, transcranial magnetic stimulation (TMS), as a probe of neuronal circuits regulating mood. In 1993, he discovered that daily prefrontal repetitive TMS over several weeks could treat depression and since then he has worked to grow the science of TMS, especially in the area of treating depression. In 1995, he set up the functional neuroimaging division and brain stimulation laboratories at MUSC that evolved into the Center for Advanced Imaging Research (now part of the Center for Biomedical Imaging) and served as its first director. He continues to use imaging (fMRI, SPECT) and stimulation (TMS, vagus nerve stimulation [VNS], electroconvulsive therapy [ECT] or deep brain stimulation [DBS]) either separately or more recently in combination to understand the brain regions involved in regulating emotion in health and disease. He is the editor-in-chief of a new journal he launched with Elsevier in 2008 called Brain Stimulation: Basic, Translation and Clinical Research in Neuromodulation. He is the author of more than 300 articles and holds 4 patents and 4 patent applications.