Figure 2.

Visual stimuli presented to the dragonfly during electrophysiological recordings from STMD neurons. Upper rows of each combination depict a snapshot in time of the 2 d display on which stimuli were presented (not to scale), whereas lower rows are space-time plots for the luminance change along the line that the feature moves. A, High contrast OFF and ON edges and a single black target are drifted from the bottom to the top of the display. B, Low contrast versions of both edges and target, with the addition of a “target” composed of two OFF edges. C, On a mean background, ON and OFF edges are composed from both mean background to light and mean background to dark transitions. Both light and dark targets are also presented.