Sexually dimorphic neural circuits underlying mating behaviors: Insights from worms, flies, and mice.

In sexually reproducing animals, males and females are biologically specialized to produce sperm or eggs, which must unite through mating to ensure successful reproduction. To facilitate this, each sex displays sex-specific, often stereotyped, mating behaviors orchestrated by neural circuits that undergo sexual differentiation during development. Extensive anatomical mapping and functional dissection in genetically tractable model organisms, including Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus, have revealed many sexually dimorphic neuronal populations and neural circuits. While previous reviews have offered broad cross-species comparisons of such sex differences in the nervous system [1,2], here we take a more focused approach. We specifically examine the neural substrates underlying mating behaviors across these three species, aiming to highlight shared principles in circuit architecture and to advance the emerging concept of connectome sex.