Meeting Abstract
Like other flies, fruit flies (Drosophila melanogaster) possess a set of modified hind wings called halteres that beat in time with the forewings and act as an inertial sensory system. These modulate fast reflexes stabilizing the head and wings of these insects against unexpected movements, mediated by direct projections of haltere mechanosensory neurons to neck and wing-steering motoneurons. While many aspects of these circuits have been described in rigorous electrophysiological studies, it remains unresolved how haltere afferents encode inertial information and what aspects of haltere mechanosensation are ultimately involved in behavior. Here, we modulate aspects of haltere kinematics and observe behavior in an effort to address these questions. Adult Drosophila were tethered to rigid pins and suspended in an insect flight arena, with which the fly was shown either a uniform visual background stimulus or a periodic grating stimulus designed to elicit an optomotor steering response in the head and wings. Concurrent with this visual stimulation, a dorso-ventral movement of one of the halteres was induced via a pair of electromagnets, acting on an iron filing glued to the haltere bulb. Under every visual context, the imposed haltere movements followed the magnetic stimulation frequency with close fidelity, and were accompanied by an identifiable jitter in power spectral density estimates of the head yaw and wing leading edge angle timeseries. In the case of the visual motion stimulus, this jitter appeared to be superimposed on the visual system response, and did not prevent the flies from showing normal optomotor head and wing responses. These findings lay the groundwork for an estimation of the “transfer function” connecting haltere mechanosensation with its downstream targets during particular behavioral contexts.
