1. From the School of Medicine (N.J.C.), Cardiff University, Cardiff, UK; the School of Medicine (M.W., P.J.D.), University of Wales, Swansea, UK; the Neurovascular Research Laboratory (J.V.B., K.A.E., D.M.B.), Faculty of Health, Science and Sport, University of Glamorgan, Pontypridd, UK; and the Cardiff University Brain Research Imaging Centre (R.G.W.), School of Psychology, Cardiff University, Cardiff, UK.