PET-study on the Role of the Reward System in Weight Loss After Bariatric Surgery

Inclusion Criteria: * Bariatric surgery 24-36 months prior to the study * Adult (over 18y old) * Mentally capable to understand the consequences of the procedure and make his or her own choice without coercion * Able to undergo PET and MRI, according to the investigator's assessment * Native speaking * Able to participate in follow-up * Written informed consent Exclusion Criteria: * Presence of a DSM-IV axis 1 disorder * The use of drugs that bind to dopamine D2/3 receptors, including various classes of antipsychotics and antidepressants * History of stroke, brain tumor, Parkinson's Disease or dementia * History of head trauma with loss of consciousness * Alcohol or substance abuse in the last 6 months * Alcohol consumption 24h prior to PET scanning * Smoking or other forms of nicotine intake 12 hours prior to PET scanning * Use of anorectic drugs in the last 6 months * Current pregnancy * Medication for Diabetes Mellitus * Claustrophobia * The presence of implanted metal objects of the type which may concentrate radiofrequency fields or cause tissue damage from twisting in a magnetic field (such as certain implanted devices, shrapnel, ocular metal shavings) * Patients with a bodyweight \> 200kg will be excluded to ensure the maximum load of the camera bed of the PET-scanner (227 kg) is not exceeded.