1 Danish Research Center for Magnetic Resonance (DRCMR), Copenhagen University Hospital Hvidovre, Kettegårds Allé 30, 2650 Hvidovre, Denmark. Electronic address: hartwig.siebner@drcmr.dk.
2 Department of Neurology and Stroke, Hertie Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany.