Leonie Oostwoud Wijdenes1, Hiroaki Gomi2, Eli Brenner3. 1. Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology University College London, 33 Queen Square, London WC1N 3BG, UK. Electronic address: l.wijdenes@ucl.ac.uk. 2. NTT Communication Science Laboratories, 3-1, Morinosato-Wakamiya, Atsugi-shi 243-01, Japan. Electronic address: gomi.hiroaki@lab.ntt.co.jp. 3. Vrije Universiteit, Faculty of Human Movement Sciences, Van der Boechorststraat 9, 1081 BT Amsterdam, Netherlands. Electronic address: e.brenner@fbw.vu.nl.