Marcus E. Raichle, MD, is professor of radiology, neurology, anatomy, neurobiology, and biomedical engineering at Washington University in St. Louis, where he also co-directs the Division of Radiological Sciences at the Mallinckrodt Institute of Radiology. He heads a team investigating brain function using positron emission tomography (PET) and functional magnetic resonance imaging (MRI) to map functional organization of the human brain, especially regions responsible for language and thought processing. He was a member of the team that developed PET at Washington University during the 1970s. His most recent research has helped to develop a better understanding of those areas of the normal human brain responsible for language, thought processing, and emotion. He is a recipient of the Bristol-Myers Squibb Award for Distinguished Achievement in Neuroscience Research.