Weighted haltere and imposed haltere stroke reduction tethered flying Drosophila kinematics

In the true flies (Diptera) the hind wings have evolved into specialized
mechanosensory organs known as halteres, which are sensitive to gyroscopic
and other inertial forces. Together with the fly’s visual system, the
halteres direct head and wing movements through a suite of equilibrium
reflexes that are crucial to the fly’s ability to maintain stable flight.
As in other animals (including humans), this presents challenges to the
nervous system as equilibrium reflexes driven by the inertial sensory
system must be integrated with those driven by the visual system in order
to control an overlapping pool of motor outputs shared between the two of
them. Here, we introduce an experimental paradigm for reproducibly
altering haltere stroke kinematics and use it to quantify multisensory
integration of wing and gaze equilibrium reflexes. We show that
multisensory wing-steering responses reflect a linear superposition of
individual haltere-driven and visually-driven responses, but that
multisensory gaze responses follow a non-linear integration logic.