[1] Natl Hosp Neurol & Neurosurg, Queen Sq, London WC1N 3BG, England
[2] Univ Coll London Queen Sq Inst Neurol, Queen Sq, London, England
[3] Univ Oxford, Hosp Natl Hlth Serv Fdn Trust, Oxford, England
[4] Univ Dundee, Sch Life Sci, Med Res Council Prot Phosphorylat & Ubiquitylat Un, Dundee, Scotland
[5] Natl Hosp Neurol & Neurosurg, Lysholm Dept Neuroradiol, Queen Sq, London, England