Electrical synapses mediate visual orientation behavior

Animals constantly detect and orient toward salient visual objects, but the neural circuits underlying this process remain poorly understood. We previously showed that T3 neurons, a visual columnar cell type in Drosophila melanogaster, drive saccadic orientation toward visual landmarks during flight. Here, we identify LC17 neurons, a visual projection cell type, as T3 downstream partners for saccadic visual orientation. Using in vivo optical physiology and virtual reality behavior, we demonstrate that LC17 neurons are broadly tuned to visual objects and necessary for object tracking during flight. Notably, this tracking behavior depends on electrical synapses. We show that the innexin Shaking B (ShakB), which forms gap junctions in the fly brain, is highly expressed in LC17 dendrites. Additionally, LC17-specific knockdown of shakB perturbs the cell physiological visual response and impairs the behavioral readout of object motion vision for saccadic orientation. Our findings reveal the mechanisms underlying visual orientation and highlight the interplay between electrical and chemical neurotransmission for object detection and rapid action selection.