Using brain-wide imaging to investigate multisensory integration in behaving Drosophila

Many natural behaviors are driven by multisensory inputs, which engage multiple pathways and brain regions simultaneously, but it is not known how multisensory inputs are combined, nor how these representations may be modulated by behavioral state. Here, we examine brainwide audiovisual integration in the context of Drosophila courtship, a dynamic social behavior in which the female receives combined auditory and visual cues from male suitors. Employing 2-photon functional imaging in head-fixed, behaving female flies presented with fictive auditory and visual cues from multiple directions, we find widespread activity correlated to both auditory and visual stimuli presentations. Critically, we have identified signals which respond to multisensory but not unisensory stimuli, as well as regions in which stimulus-evoked activity is modulated by the animal’s locomotor state. Aligning these data to the recently completed fly whole-brain connectome allows us to map activity onto the anatomical network, identifying putative cell types and circuit motifs engaged in multisensory processing. This work lays the foundation for connectome-constrained computational models trained on locomotor and whole-brain functional data, and for follow-up experiments to validate putative multisensory integration circuits.