1. Faculty of Medicine and University Hospital, Department of Neurology, University of Cologne, Germany (S.J.B., L.H., S.V., C.T., S.U.V., M.R., M.S., G.R.F., C.G., M.A.R.).
2. In-Vivo NMR Laboratory, Max Planck Institute for Metabolism Research, Cologne, Germany (S.J.B., A.M., S.V., M.R., M.S., M.H., C.G., M.A.R.).
3. Cognitive Neuroscience Section, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Germany (S.J.B., L.H., C.T., M.S., G.R.F., M.H., C.G., M.A.R.).