Fig. 3

(A) Layout of individual LEDs in our spherical visual stimulation arena. The visual stimulus consisted of a pattern of vertical bars meant to simulate the fish swimming through a pipe with transverse stripes. Fish were placed in the center of the spherical arena, thus allowing for stimulation of an extended range of elevations (almost 140° × 360° of its visual field).

(B) During individual trials, stripes in different regions of the visual field were moving (example areas marked green or purple), whereas the rest remained static. Stimulus motion was from back to front, providing the percept of backward drift to the fish.

(C) Tail bend angles were measured for each recorded video frame to calculate behavioral responses to different stimulus locations. Fish generally responded more strongly to motion in the lower (purple trial), than in the upper (green trial) visual field.

(D) Heatmap color indicates the strength of the OMR to motion stimuli in different parts of the visual field. OMR drive was strongest for motion in the lateral lower visual field. To quantify the behavioral response, the number of tail beats per unit time was averaged over repeated trials for each fish, normalized by the fish’s maximum response to any of the stimuli, and scaled by the inverse of the area (in steradians) that was active (i.e., moving) for each stimulus to account for effects of stimulation area size on response strength. Responses were then combined into a single average across fish (n = 8 fish). Motion stimuli covered 19 different combinations of positions and steradian sizes in visual space.

See also Figure S1.