Male Drosophila CNS Connectome Architecture and Sex-Specific Neural Circuits

Researchers present the first finished connectome of an entire male Drosophila central nervous system, encompassing the central brain, optic lobes, and the ventral nerve cord. This milestone resource provides a fully proofread and annotated male brain and nerve cord connectome with an intact neck connective, enabling comprehensive synaptic-resolution comparisons across sexes in an adult animal with complex behaviors. Comparative connectomics between male and female fly brains reveals 262 sex-specific and 114 sexually dimorphic cell types, accounting for 4.8 percent of the central brain. The study demonstrates that sex-specific and dimorphic neurons concentrate in higher-order brain centers while sensory and motor peripheries remain largely isomorphic, with dimorphic connectivity propagating brain-wide influence despite modest structural changes. The project bridges structural biology and neural circuitry by detailing specific pathways, such as visual-motor connections spanning from R1-R6 visual neurons to the DNg13 motor neuron, and providing examples of dimorphic cells like type AOTU012. These findings illuminate the fundamental architectural principles governing sex-shared, sex-specific, and flexible behavioral capacities. Data acquisition and analysis were collaboratively performed by the FlyEM Project Team at HHMI-Janelia, the Cambridge Connectomics Group, and Google Research, supported by organizations such as the Howard Hughes Medical Institute, the Wellcome Trust, and the Medical Research Council. The dataset is fully accessible through tools like Neuprint, Clio, and Neuroglancer for global neuroscience research.