Directional invariance in the Drosophila giant fiber escape circuit

An animal’s nervous system recognizes visual features regardless of where the visual feature is located. However, the underlying mechanisms that enable location invariant feature detection are not fully understood, particularly when visual feature information contributed by each eye needs to be resolved. Here we investigate directional invariance of looming responses in descending neurons (DN) of Drosophila melanogaster . We find multiple looming responsive DN integrate looming information across both eyes, even though their dendrites are unilateral. One DN in particular, the giant fibers (GF), generates invariant looming responses across approach directions. We confirm visual information propagates to the GF from the contralateral eye through an as of yet unidentified pathway and demonstrate the absence of this pathway alters GF responses to looming stimuli from the ipsilateral eye. Our data highlight a role for bilateral visual integration in generating consistent escape responses that are robust across a wide range of stimulus locations and parameters.