Behavioral contributions of the 12 neuron types in the fly lamina. Michael B. Reiser¹, John C. Tuthill^1,2, Aljoscha Nern¹, Gerry Rubin¹. 1) Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA; 2) Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA.

   Motion detection is a fundamental neural computation performed by many sensory systems. In the fly, local motion computation is thought to occur within the first two layers of the visual system, the lamina and medulla. We constructed specific genetic driver lines for each of the 12 neuron classes in the lamina. We then depolarized and hyperpolarized each neuron type, and quantified fly behavioral responses to a diverse set of motion stimuli. We found that only a small number of lamina output neurons are essential for motion detection, while most neurons serve to sculpt and enhance these feedforward pathways. Two classes of feedback neurons and two classes of lamina output neurons are required for normal detection of directional motion. Our results reveal a prominent role for feedback and lateral interactions in motion processing, and demonstrate that motion-dependent behaviors rely on contributions from nearly all the neurons in the lamina.