[1] Gloucestershire Royal Hosp, Dept Neurol, Gloucester GL1 3NN, England
[2] Univ G DAnnunzio, Dept Neurosci Imaging & Clin Sci, I-66013 Chieti, Italy
[3] Natl Univ Singapore, Yong Loo Lin Sch Med, Ctr Translat Med, Dept Med, Singapore 117599, Singapore
[4] Natl Univ Singapore, Yong Loo Lin Sch Med, Ctr Translat Med, Dept Physiol, Singapore 117599, Singapore