Fig. 6.
Experimental setup and visual stimuli. (A) Flies are rigidly tethered to pins and suspended between an infrared (IR) LED and two photodiodes, which measure the difference between the fly's left and right wingbeat amplitudes (ΔWBA). They are surrounded by an arena of green LED panels on which various stimuli can be displayed. A camera above the fly records an image of the fly's head (inset), and the angle of the head (θh) is measured with tracking software. (B) Our stimulus consisted of a randomly textured wide-field panorama and a randomly textured bar that could be moved independently. Here, we show space–time plots of a stimulus consisting of simplified motion of only one stimulus component. (C) Triangle-wave stimuli showing figure and wide-field motion moving with two different frequencies of oscillation.