[1] Univ Barcelona, Fac Med, Dept Psychiat & Clin Psychobiol, Barcelona 7, Spain
[2] Inst Biomed Res August Pi & Sunyer IDIBAPS, Barcelona, Spain
[3] Hosp Clin Barcelona, Neurol Serv, Parkinsons Dis & Movement Disorders Unit, Barcelona, Spain
[4] Ctr Diagnost La Imatge Hosp Clin Barcelona CDIC, Barcelona, Spain
[5] Univ Oxford, Oxford Ctr Funct Magnet Resonance Imaging Brain F, Oxford, England