[1] Univ Helsinki, Dept Psychol, Fac Med, Helsinki, Finland
[2] Univ Helsinki, Dept Neurol, Helsinki, Finland
[3] Helsinki Univ Hosp, Helsinki, Finland
[4] Lapland Cent Hosp, Dept Neurol & Clin Neurophysiol, Rovaniemi, Finland
[5] Univ Gothenburg, Sahlgrenska Acad, Dept Clin Neurosci, Inst Neurosci & Physiol, Gothenburg, Sweden
[6] Sahlgrens Univ Hosp, Dept Neurol, Gothenburg, Sweden