Drosophila brain gates the flow of visual information from the eyes.

(A) A fly faces identical screens of black and white stripes on its left and right, and we measure the outputs of its left (red) and right (blue) optic lobes, as power-indexes (20–100 Hz frequencies) of their LFPs. When the scenes are set to motion, the left and right power indexes oppose each other (i.e. these are 180° phase shifted), alternating in synchrony with the orienting behavior (black). Light grey sections highlight switch-like torque responses to right; dark grey sections to left. Notice also the effect of saliency in the power index; the overall neural activity settles down from the initial maxima as the fly continues choosing between the stimuli. (B) The behavior-triggered average of the right (blue) and left (red) optic lobe's power-indexes during right-to-left and left-to-right torque responses (black); torque, arbitrary units. When a fly's orienting flips sides, its brain activity is readily enhanced on the chosen side but more gradually suppressed on the opposite side. (C) The difference in power-indexes (green) predicts the behavior in (B). Mean ± SEM of 5 flies. For details of the calculations and individual experiments, see Fig. S10.