Figure 7. Neural output of the optic lobes increases on the side chosen for torque response.

Changes (Δ) in the average transmission of visual motion information are shown for opposing choices (A, B; relative change for firing rates) in flying flies, and for opposing visual stimuli (C, D) in resting flies. Despite seeing equal but opposite motion stimuli (moving scenes of black and white stripes) on its left and right, the activity of the optic lobes changes when a fly chooses the stimulus for its torque response to (A, B) as if the left and right scenes were presented alternatingly to the fly at rest (C, D). (A) Choosing the left stimulus (torque down) boosts the output of the left optic lobe; (B) choosing the right stimulus (up) boosts the output of the right. This data, aligned by the zero-crossings (dotted) in the torque (top) with left/right division (dark/light grey), is from an experiment containing 22 nearly symmetrical choices (switch-like torque responses) to left and right in Figs. 6B–C. Changes in firing rates and LFPs in the left (red) and right (blue) optic lobes, shown when a fly chooses ipsi- and contralateral sides, respectively. (C, D) At rest (zero-torque): left stimulus boosts LFP of the left optic lobe more than right stimulus (C, bottom); the right optic lobe also prefers ipsilateral stimulation (D, bottom). Due to the one-sided stimulation of step-like movements, these differences are larger and more transient than when a fly's chooses between the stimuli (A, B). Mean firing (C, D, middle) shows less modulation as averaging cancels out ipsi/contralateral preferences of individual sites (cf. Fig. S8A). The data in (C, D) is from 6 flies in Fig. 4. Torque, arbitrary units; means ± SEMs shown.