The Bdnf gene encodes a neurotrophin with critical roles in brain development and function. Bdnf exerts positive effects on neuronal survival and differentiation, and on synaptic plasticity. It is therefore important in learning and memory, and neuronal regeneration, as well as neurodevelopment. I am elucidating the genome architectural changes that accompany Bdnf activation during brain development and neuronal activation. We show that the mouse Bdnf gene is regulated by topological mechanisms including movement away from the nuclear periphery during development. We have identified a novel enhancer region that loops to the Bdnf gene in differentiating neurons and is critical for Bdnf upregulation during development and consequently for Bdnf-mediated dendritic growth. This has implications in many neuronal diseases, since Bdnf is downregulated in neuro-developmental, -psychiatric and -degenerative disorders, and conversely its upregulation has a neuroprotective effect.