Fig. 5. The combination of enhanced rotation responses and suppressed expansion responses persists under conditions in which the fly has active control of image motion. (A) An example position trace shows the small remnant of a sinusoidal bias added to the control of the fly over the arena heading. (B) Top, mean WBA responses with odor (red) and without odor (blue) (N=43). Bottom, the frequency-modulated stimulus position waveform of the imposed bias. (C) Mean peak-to-peak response amplitude for each consecutive stimulus epoch. The response amplitude was quantified and tested statistically using fitted sine functions. WBA response amplitudes were significantly enhanced by odor at all frequencies for rotation (two-factor repeated measures ANOVA, P<0.001) but were only suppressed significantly between 2 Hz and 8 Hz for expansion (two-factor repeated measures ANOVA, P<0.05).