Vision provides animals with detailed information about their surroundings, conveying diverse features such as color, form, and movement. Computing these parallel spatial features requires a large and diverse network of neurons, such that in animals as distant as flies and humans, visual regions comprise half the brain’s volume. These visual brain regions often reveal remarkable structure-function relationships, with neurons organized in spatial maps with shapes that directly relate to their roles in visual processing.

Our group has used the Drosophila motion pathway to map the connected biological computations that estimate optic flow—the pattern of changes that self-motion induces in the visual scene. We identified, targeted with genetic tools, and functionally characterized cell types across six layers of the brain—from photoreceptors through directionally selective neurons to central circuits that disambiguate global optic flow patterns. By combining computational neuroanatomy with functional measurements, we traced how each step-by-step transformation contributes to perception and behavior. To explain long-standing puzzles in fly visual responses, we expanded our mapping to the sensory organs themselves and discovered that the global organization of directionally selective neurons’ preferred directions is determined mainly by the fly’s compound eye, revealing intimate connections between eye structure, functional properties of neurons, and locomotion control.

Time and again, high-resolution anatomy has provided crucial functional insights, motivating us to extend these methods to an entire visual system. We recently completed a comprehensive Drosophila optic lobe connectome, sorting ~53,000 neurons into ~700 cell types, and paired this with genetic driver lines matched to connectome-defined cell types and accessible analytical tools for exploration. I will present examples of how working between single-cell characterization and large connectomic approaches accelerates discovery in the fly visual system, where convergent anatomical, functional, and genetic approaches reveal both the hierarchical logic of biological computations and the stunning organization of a complex visual system.