[1] Luzerner Kantonsspital, Neurol & Neurorehabil Ctr, Luzern, Switzerland
[2] Univ Hosp Bern, Inselspital, Percept & Eye Movement Lab, Dept Neurol, Bern, Switzerland
[3] Univ Hosp Bern, Inselspital, Percept & Eye Movement Lab, Dept Clin Res, Bern, Switzerland
[4] Univ Bern, ARTORG Ctr Biomed Engn Res, Bern, Switzerland
[5] Univ Hosp Bern, Inselspital, Inst Diagnost & Intervent Neuroradiol, SCAN, Bern, Switzerland
[6] Univ Hosp Psychiat, Bern, Switzerland
[7] Univ Bern, Gerontechnol & Rehabil Grp, Bern, Switzerland
[8] NINDS, Human Motor Control Sect, NIH, Bldg 36,Rm 4D04, Bethesda, MD 20892 USA