[1] Univ Cambridge, Behav & Clin Neurosci Inst, Cambridge CB2 3EB, England
[2] Univ Cambridge, Dept Expt Psychol, Cambridge CB2 3EB, England
[3] Univ Cambridge, Dept Psychiat, Cambridge CB2 3EB, England
[4] Univ Cambridge, Wolfson Brain Imaging Ctr, Dept Clin Neurosci, Cambridge CB2 0QQ, England
[5] GlaxoSmithKline Inc, Clin Unit Cambridge, Addenbrookes Ctr Clin Invest, Cambridge CB2 2GG, England
[6] Natl Hlth Serv Trust, Cambridgeshire & Peterborough Fdn, Cambridge CB21 5EF, England