[1] Leiden Univ, Ctr Med, Dept Neurophysiol, NL-2300 RC Leiden, Netherlands
[2] Leiden Univ, Ctr Med, Dept Neurol, NL-2300 RC Leiden, Netherlands
[3] Univ Glasgow, So Gen Hosp, Dept Neurol, Glasgow, Lanark, Scotland
[4] Nagoya Univ, Sch Med, Dept Biochem, Nagoya, Aichi, Japan