Small-amplitude head oscillations result from a multimodal head stabilization reflex in hawkmoths

Abstract

In flying insects, head stabilization is an important reflex which helps to reduce motion blur during fast aerial maneuvers. This reflex is multimodal and requires the integration of visual and antennal mechanosensory feedback, each operating as a negative-feedback control loop. As in any negative-feedback system, the head stabilization system possesses inherent oscillatory dynamics that depends on the rates and latencies of the sensorimotor components constituting the reflex. Consistent with this expectation, we observed small amplitude oscillations in the head motion (or head wobble) of the Oleander hawkmoth Daphnis nerii. We show here that these oscillations emerge from the inherent dynamics of the multimodal reflex that underlies gaze stabilization, and the amplitude of the head wobble is a function of both the visual feedback and antennal mechanosensory feedback from the Johnstons organs. The head wobble is thus an outcome of a multimodal, dynamically-stabilized head positioning reflex.