[1] Royal Holloway Univ London, Dept Psychol, Lab Act & Body, Egham TW20 0EXU, Surrey, England
[2] UCL, Inst Neurol, Dept Brain Repair & Rehabil, London, England
[3] UCL NHS Trust, Natl Hosp Neurol & Neurosurg, Auton Unit, London, England
[4] UCL, Wellcome Trust Ctr Neuroimaging, London, England
[5] UCL, Inst Cognit Neurosci, London, England
[6] UCL, Sobell Dept Motor Neurosci & Movement Disorders, London, England