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Abstract

Animals must be able to discriminate self-generated (reafferent) from external (exafferent) sensory input. Otherwise, the former could interfere with perception and behavioral actions. The way this can be achieved is through an efference copy, which suppresses reafferent sensory input. An example for this is the optomotor response of the fly. With the optomotor response, flies stabilize a straight flight path by correcting for unintended deviations, which they sense as visual motion of their surrounding or optic flow. HS cells of the fly are tuned to rotational optic flow and are thought to mediate optomotor responses to horizontal motion. It has been shown that during spontaneous turns, an efference copy influences the membrane potential of HS cells. Here we investigate the influence of an efference copy during looming-elicited evasive turns combined with a subsequent optomotor stimulus in Drosophila. We show that looming stimuli themselves can influence the processing of preferred-direction motion in HS cells. In addition, an efference copy can influence visual processing during saccades in both directions, but only in a subset of cells. Our study supports the notion that processing of sensory information is finely tuned and dependent on both stimulus history and behavioral context.