Meeting Abstract
Visual motion perception is critical to many animal behaviors, and flies have emerged as a powerful model system for exploring this fundamental neural computation. Several recent studies have suggested that visual motion computation in Drosophila occurs in two parallel pathways, one that is selective to light increments (ON) and another that is selective to light decrements (OFF). To examine the emergence of directional selectivity in the ON pathway, we developed genetic driver lines for each of the major neuron types in the ON pathway. Using calcium imaging, we found that the output neuron type of the pathway (T4 cells) is directionally selective but its majors inputs (Mi1, Tm3, Mi4, and Mi9 cells) are not, indicating that directional selectivity emerges in T4 cells. By individually silencing each of the input neuron types, we identified which input neurons are necessary for T4 directional selectivity and ON motion behavioral responses. We then determined the sign of the connections between these neurons and T4 cells using neuronal photoactivation. Our results suggest a specific computational architecture for motion detection that is a hybrid of classic models for motion computation.
