[1] Luzerner Kantonsspital, Div Restorat & Behav Neurol, Dept Internal Med, CH-6000 Luzern 16, Switzerland
[2] Univ Hosp Bern, Inselspital, Dept Neurol, CH-3010 Bern, Switzerland
[3] Univ Hosp Bern, Inselspital, Percept & Eye Movement Lab, CH-3010 Bern, Switzerland
[4] Univ Hosp Bern, Inselspital, Dept Clin Res, CH-3010 Bern, Switzerland
[5] Univ Bern, Bern, Switzerland