[1] Royal Ctr Def Med, Birmingham, W Midlands, England
[2] Univ London Imperial Coll Sci Technol & Med, Div Expt Med, Computat Cognit & Clin Neuroimaging Lab, London, England
[3] Univ London, London, England
[4] Univ London Imperial Coll Sci Technol & Med, MRC Clin Sci Ctr, London, England
[5] Imperial Coll Healthcare NHS, Charing Cross Hosp, Dept Imaging, London, England
[6] UCL, Inst Neurol, London, England