1. Department of Neurology; Medical University of Vienna; Vienna Austria
2. MR Center of Excellence; Medical University of Vienna; Vienna Austria
3. Perception and Eye Movement Laboratory; Departments of Neurology and Clinical Research; Inselspital, University Hospital Bern; Bern Switzerland
4. Neurology and Neurorehabilitation Center; Luzerner Kantonsspital; Luzern Switzerland
5. Office of the Clinical Director; National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda MD USA
6. Human Motor Control Section; National Institute of Neurological Disorders and Stroke; National Institutes of Health; Bethesda MD USA