Figure 7. Global motion discrimination in optomotor behavioral responses.

A: Experimental setup. B: Compound global motion stimuli. Local moving light edges spanning the entire vertical extent of the stimulus screen were offset in time and space such that they formed global patterns that either matched (“Matched Sequence”) or opposed (“Opposed Sequence”) the direction of local motion. The same stimuli were presented on each of the three screens surrounding the fly. Static 2° light bars were presented for 0.5 s prior to the onset of motion, in order to avoid startle responses to the sudden appearance of moving edges. C: Fly turning responses to light edges moving 27°/sec (left panel) or 54°/sec (right panel) that formed either matched (green lines) or opposed (magenta lines) sequences, plotted over time. The light and dark gray boxes indicate presentation of static 2° light bars (light gray) followed by the sequential presentation of four moving light edges (dark gray). D-E: Integrated turning responses to light (D, N=19 flies) and dark (E, N=23 flies) edges in local-global matched or opposing patterns.