The generation of neurons during development from a fertilized egg requires a cascade of neuronal lineage-specific genes. Proneural genes, a highly conserved family of basic helix-loop-helix (bHLH) transcription factors, are key members of these genetic cascades. Yet, the upstream molecular events that directly regulate the expression of proneural genes remain poorly understood. Bilaterian nervous systems are largely left-right (L/R) symmetrical yet certain structures are present asymmetrically. How asymmetric neurogenesis is regulated is unclear. We investigate the regulatory logic of early neural specification and asymmetric neurogenesis using forward genetic screens, 4D-lineage screens and promoter analysis.