The research in the Ma laboratory focuses on nerve branching, a key step in establishing synaptic connection during neural circuit development. Nerve branches associated with axons and dendrites are seen in almost every nerve cell (Fig.1), yet the mechanisms underlying their formation is not well understood. How do branches form at the right time and in the right place? How do they establish specific size and pattern? How are they determined by genetic programs and influenced by environmental factors? How do they remodel in response to experience or injury? How are they affected in neurological disease, and how do they contribute to developmental disorders? To address these fundamental questions, three major research directions are currently being pursued in the laboratory.