Adaptive feedforward speed control in Drosophila
Insects demonstrate remarkable agility in flight despite constant changes in flight dynamics throughout their lives. However, it is unclear whether such resilience is conferred via purely feedback control or whether adaptive feedforward control mechanisms are present. This study examines whether adaptive feedforward control mechanisms are present in Drosophila melanogaster flight, by comparing the free-flight trajectories with and without wing damage and antennae ablation. Flies with partial wing excisions exhibited increased flight speeds in the dark compared to intact-wing controls. Upon exposure to visual contrast in light, the clipped-wing flies reduced their speed comparable to that of the control group flies. Notably, the lower speed persisted upon returning to the dark, indicating an enduring change to the flight controller. To discern between feedforward adaptation and a change in mechanosensory feedback gains, we replicated the experiment after ablating the antennal arista, the primary mechanosensors for sensing airspeed. Although flies with ablated antennae flew with greater variance in speed, they displayed a parallel trend in mean speed adaptation: increased speed in the dark, compensation in the light, and sustained lower speed in subsequent dark conditions. This consistent pattern strongly supports the involvement of adaptive feedforward control rather than the adjustment of mechanosensory feedback gains. Our investigation unveils an adaptive strategy in D. Melanogaster flight, illustrating its ability to set flight speed through adaptive feedforward control mechanisms.