This supplement will help Dr. M. Tauber complete the study awarded in 2011: Early to midterm oxytocin effects on the brain metabolism of adults with Prader-Willi syndrome. Prader-Willi syndrome (PWS) is a rare multisystem genetic disease leading to severe disabilities such as morbid obesity, as well as behavioral and socialization problems. We are greatly lacking in information on the natural history of this complex disease and the factors involved in its progression and outcome. Early diagnosis and a multidisciplinary approach can prevent obesity in most cases, while behavioral and psychiatric problems often remain unresolved. Recent imaging studies in patients with PWS have shown hypoperfusion in anterior cingulum known to be related with understanding of social codes. Moreover, oxytocin (OT) administration is involved in establishing and maintaining social codes. Its modality of administration isn’t yet known and has to be determined to help patients with PWS understanding their social environment. https://www.fpwr.org/grant/2011/early-midterm-oxytocin-effects-brain-metabolism-adults-prader-willi-syndrome