Moritz Helmstaedter is a neuroscientist dedicated to mapping connectomes, the complex networks of nerve cells in the brain. A medical doctor and physicist by training, Moritz completed his doctoral thesis with Nobel laureate Bert Sakmann at the Max Planck Institute for Medical Research in Heidelberg, Germany. During his post-doctoral work, together with Winfried Denk and Kevin Briggman, he developed methods to map nerve cell networks using electron microscopes and computer analysis tools. This is making it possible for the first time to decipher large complex networks in the brain at single-cell resolution. He is currently setting up his own laboratory at the Max Planck Institute of Neurobiology in Munich, where he aims to understand the computations in sensory cortex, and to unravel what distinguishes a human brain from, say, that of a mouse, at the structural level. Moritz has pioneered crowd sourcing for connectomics, engaging more than a hundred students to work together to analyze the immense amounts of data. Going forward, he aims at motivating thousands of curious minds to collaborate online on the task of reconstructing the powerful and fascinating neuronal networks of the brain.