The aim of this study is to evaluate a novel therapeutic approach for the treatment of brain dysfunction in a mouse model of Rett syndrome (RTT), a severe autism spectrum disorder (ASD). In addition, it will define how a common variation in one gene, Brain-Derived Neurotrophic Factor (BDNF), may influence brain function in RTT, as well as the response to therapy. The basis of this approach is the use of newly developed compounds that mimic the activity of BDNF, a critical brain molecule which is in deficit in RTT. These compounds bind to and activate the BDNF receptor, TrkB. Recent studies by the research team demonstrated that RTT mice exhibit abnormalities in a measure of cognitive function that is also disrupted in other ASDs, and that normal function can be restored with one of these TrkB compounds. These studies aim both to shed further light on the role of BDNF availability in cognitive dysfunction in RTT and to determine how variant BDNF alleles may influence the efficacy of TrkB agonist treatment. Together, the research addresses the Autism Speaks priority areas: 1) identify novel treatments for ASDs; and 2) understand the molecular pathophysiology of ASDs to inform translational research. Given the shared features of RTT and other ASDs, it is hoped that these studies will yield insight into the potential role of TrkB agonists in the treatment not only of RTT patients but of those afflicted with other ASDs as well.