Neural Circuits for Motion Vision in the Fly

Seeing the direction of motion is fundamental for visual navigation, predator avoidance, and prey capture. However, the direction of motion is not explicitly represented at the level of individual photoreceptors. Rather, directional motion information needs to be extracted from the photoreceptor array by comparing the signals of neighboring photoreceptors over time. The exact nature of this process as implemented in the Drosophila visual system is currently being studied in great detail, and much progress has recently been made in determining the neural circuits giving rise to directional motion information in this species.