1. From the Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.).