An Investigation on the Impact of Newly Identified Contralateral Wing Interneuron (cWIN) and its comparison with the Contralateral Haltere Interneuron (cHIN) during Flight in Drosophila melanogaster

Abstract

The ability to perform body movements, especially during unexpected environmental changes, requires the transformation of sensory information into precise motor movement. Drosophila melanogaster can be leveraged as a model organism to investigate rapid motor control, namely wing-steering muscle activity on a sub-millisecond time interval. This level of motor precision can be credited to their haltere organs which serve as gyroscopic sensors, detecting the rotational movement, and stimulating equilibrium reflexes to maintain flight stability. Recent connectomics work in the organization of the haltere sensory afferents shows that these neurons project both directly onto wing-steering muscles but also indirectly via interneurons. One subclass of interneurons, the contralateral haltere interneurons (cHINs), have been long established anatomically. Connectomics work now provide predictions about the role of these neurons in flight, yet these hypotheses remain untested. Here, I harness the power of genetic drivers, optogenetics, and quantitative behavior to study the behavioral effects of these interneurons along with the newly identified contralateral wing interneurons (cWINs). Results first indicate that optogenetic activation of the cHINs considerably decreases body saccade magnitude and duration while no significance was observed under cWIN activation. More notably, both cHIN and cWIN activation substantially increase compensatory head yaw magnitude following peak angular body velocity. These saccade performances in flies, i.e., rapid turns, can further prompt us in understanding the visual saccades we perform as primates and the implications of disynaptic connections to motor circuitry.