Effects of Sex Steroid Hormones on Human Brain Function, Structure and Connectivity

This ultrahigh-field MRI study gives us the unique opportunity to measure changes in brain function and structure induced by long-term opposite-sex steroid hormone administration in transsexual subjects. Our aim is 1. to prove the influence of high-dose, long-term opposite-sex steroid hormone treatment on functional brain response in transsexuals. 2. to investigate the influence of hormone treatment on resting state functional connectivity and brain morphology. 3. to investigate differences between transsexuals and healthy control subjects in brain function and functional connectivity, brain morphology and structural connectivity. In this longitudinal study, transsexuals and healthy control subjects will undergo three 7 Tesla ultrahigh-field MRI scan sessions: 1. baseline (before hormone treatment), 2. after 4 weeks of treatment and 3. after 4 months of treatment.