Meeting Abstract

3.2  Monday, Jan. 4  Visual rotation stimuli drive activity of intrinsic antennal muscles in Manduca sexta HINTERWIRTH, A.J.*; DANIEL, T.L.; University of Washington; University of Washington ahinterw@u.washington.edu

Mechanosensory functions of insect antennae play vital roles in flight control by acting as air flow sensors or as gyroscopic organs that detect rapid body rotations via Coriolis forces.  There are, for example, proposed reafferent circuits that drive antennal muscles in response to wind stimuli, keeping the antennal posture independent of flight speed.  Similarly, mechanical stimulation of antennae drive reflexive steering motions of the abdomen.  There is, however, no evidence to suggest that visual stimuli have a direct effect on antennal mechanosensory systems during flight. As with halteres in Diptera, such stimuli could be implicated in the flight control pathway.  We use a combination of behavioral and electrophysiological approaches to show that visual motion generated during body rotations has an effect on antennal position. While presenting visual pitch stimuli to a tethered animal, we measured antennal position with high-speed videography. Additionally, we recorded EMG signals from intrinsic antennal muscles in the scape that influence antennal position (N=4 animals). A downward visual pitch motion stimulus causes the firing rate in the intrinsic muscle to increase, which leads to a backwards movement of the antenna. Therefore, by directly affecting the mechanical signal perceived at the base of the antennae, visual input from the eyes feeds back to antennal mechanoreceptors, which we have shown  influence abdominal flexion. This eye-antenna feedback does not, however, depend on downstream circuits of the thorax or abdomen, and can be elicited in an isolated head preparation. Visual control of mechanosensory information could be used to tune antennal responses to body rotations.