Understanding the developmental trajectories of neuronal lineages is crucial for elucidating how they are assembled into functional neural networks. Studies investigating the nervous system development in model animals have focused only on a few regions of the Central Nervous System due to the limited availability of genetic drivers to target these regions throughout development and adult life. This hindered our understanding of how distinct neuronal lineages come together to form neuronal circuits during development. Here, we present a split-GAL4 library composed of driver lines, which we generated via editing the endogenous locus of the lineage specific transcription factors and demonstrate that we can use the elements of this library to specifically target the majority of individual neuronal lineages in the Drosophila ventral nerve cord (VNC) across development and adulthood. Using these genetic lines, we found striking morphological changes of neuronal processes within a lineage during metamorphosis. We also showed how neurochemical features can be quickly assessed for a class of neurons expressing a specific gene. Lastly, we documented behaviors elicited in response to optogenetic activation of individual neuronal lineages and generated a comprehensive lineage-behavior map of the entire fly VNC. Looking forward, this lineage-specific driver library will provide genetic handles to address the questions emerging from the analysis of the recent VNC connectomics and transcriptomics datasets.
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