Fig. 7. Gaze and response of a rotation-sensitive elementary motion detector (EMD) system for two single flies flying in a stationary random-dot environment (A–E) and under optomotor stimulation due to the rotating arena (500° s^–1 counter-clockwise rotation, F–J). The time traces in B–E and G–J are subsets of the flight sequences in A and F. (A,F) Flight path and EMD response (left-minus-right eye) plotted in pseudo-colour for both stimulus conditions. Red cross, arena centre. (B,G) The fly's gaze was derived according to the procedure shown in Fig. 1D. The movement of the cylinder panorama (infrared light marker) is shown in red (right scale). (C,H) EMD response of left (blue) and right (red) eye derived according to the position and speed of the fly inside the arena and the visual panorama. (D,I) Left-minus-right eye EMD response (black) and turning velocity (red), and (E,J) left-plus-right eye EMD response (black) and horizontal velocity (red) are plotted for both stimulus conditions. Upper dotted line in D and I indicates the threshold used to identify flight saccades (>1000° s^–1). Grey dots indicate times at which flight saccades occur. Black, left scale; red, right scale.