Research in the Alex Kolodkin Laboratory is focused on understanding how neuronal connectivity is established during development. Our work investigates the function of extrinsic guidance cues and their receptors on axonal guidance, dendritic morphology and synapse formation and function. We have investigated how neural circuits are formed and maintained through the action of guidance cues that include semaphorin proteins, their classical plexin and neuropilin receptors, and also novel receptors. We employ a cross-phylogenetic approach, using both invertebrate and vertebrate model systems, to understand how guidance cues regulate neuronal pathfinding, morphology and synaptogenesis. We also seek to understand how these signals are transduced to cytosolic effectors. Though broad in scope, our interrogation of the roles played by semaphorin guidance cues provides insight into the regulation of neural circuit assembly and function. Our current work includes a relatively new interest in understanding the origins of laminar organization in the central nervous system.