[1] MRC, Cognit & Brain Sci Unit, 15 Chaucer Rd, Cambridge CB2 7EF, England
[2] Univ Oxford, Dept Psychiat, Warneford Hosp, Oxford OX3 7NG, England
[3] Univ Utrecht, Dept Clin Psychol, NL-3584 CS Utrecht, Netherlands
[4] Karolinska Inst, Dept Clin Neurosci, S-10401 Stockholm, Sweden
[5] UCL, Wellcome Trust Ctr Neuroimaging, 12 Queen Sq, London WC1N 3BG, England