[1] Univ Bologna, Dipartimento Med Clin & Biotecnol Applicata D Cam, Bologna, Italy
[2] Univ Oxford, Dept Biochem, MRC, Biochem & Clin Magnet Resonance Unit, Oxford, England
[3] Oxford Radcliffe Hosp, Oxford, England
[4] UCL, Royal Free & Univ Coll Sch Med, Univ Dept Clin Neurosci, London, England