[1] Kuopio Univ Hosp, Dept Neurol, FI-70211 Kuopio, Finland
[2] Univ Kuopio, Dept Phys, FIN-70211 Kuopio, Finland
[3] Univ Kuopio, Inst Clin Med, Neurol Unit, FIN-70211 Kuopio, Finland
[4] Kuopio Univ Hosp, Dept Clin Radiol, FI-70211 Kuopio, Finland
[5] Kuopio Univ Hosp, Dept Clin Neurophysiol, FI-70211 Kuopio, Finland
[6] McGill Univ, Montreal Neurol Inst, McConnell Brain Imaging Ctr, Montreal, PQ, Canada
[7] Karolinska Inst, Aging Res Ctr, Stockholm, Sweden