Joseph Shomar

Animals are often tasked with determining how far away salient objects are in order to successfully navigate and survive in their environment. Here, we design a novel high-throughput assay in which several individually compartmentalized Drosophila encounter various differently sized gaps during free locomotion. Using this assay, we conduct a targeted screen to identify neurons that contribute to the fly’s ability to visually determine the size of the gaps they encounter. We find that silencing T4 and T5 neurons, the primary motion detectors in the fly visual system, eliminates flies’ ability to estimate distances in this paradigm. Additionally, we identify a visual projection neuron in the lobula, LC15, as a key contributor to the fly’s ability to estimate distances. Using two-photon microscopy and in vivo calcium indicators, we characterize the response properties of LC15 neurons to various distance-like visual stimuli. The response properties suggest that the neuron encodes signals relevant for the implementation of a motion parallax algorithm. Simulations of object motion in the visual field of a moving observer provide further interpretation of LC15’s response properties in the broader context of motion parallax.