Visuomotor strategies for object approach and aversion in Drosophila melanogaster

Abstract

Animals classify stimuli to generate appropriate motor actions. In flight, Drosophila melanogaster classify equidistant large and small objects with categorically different behaviors: a tall object evokes approach whereas a small object elicits avoidance. We studied visuomotor behavior in rigidly- and magnetically-tethered D. melanogaster to reveal strategies that generate aversion to a small object. We discovered that small object aversion in tethered flight is enabled by aversive saccades and smooth movement, which varies with the stimulus type. Aversive saccades to a short bar had different dynamics than approach saccades to a tall bar and the distribution of pre-saccade error angles were more stochastic for a short bar. Taken together, we show that aversive responses in Drosophila are driven in part by processes that elicit signed saccades with distinct dynamics and trigger mechanisms. Our work generates new hypotheses to study brain circuits that underlie classification of objects in D. melanogaster.