Meeting Abstract

51.1  Thursday, Jan. 6  Neuromuscular Control of Yaw Turns in the Hawkmoth Manduca sexta SPRINGTHORPE, D*; FERNANDEZ, MJ; HEDRICK, TL; Univ. of North Carolina at Chapel Hill; Univ. of North Carolina at Chapel Hill; Univ. of North Carolina at Chapel Hill dwight@email.unc.edu

Recent models of turning in flapping flight suggest that yaw turns are highly damped, potentially reducing control of these behaviors to a first order system where displacement is proportional to muscle activation. This contrasts with classical, undamped systems where acceleration is proportional to force. To investigate this possibility we used high-speed videography to reconstruct in 3D the flight paths of free-flying hawkmoths (Manduca sexta) engaged in multi-wingbeat yaw turns. We simultaneously collected bilateral electromyograms (EMG) from the principle down-stroke flight muscles, the dorsal longitudinal muscles (DLM), using two sets of paired tungsten wire electrodes connected to an external amplifier. We examined the left-right differences in neural activation for correlation with the whole wingbeat average angular velocity and acceleration. As hypothesized, the left-right activation differences were a significant (p < 0.01, n=5) predictor of angular velocity but not angular acceleration, with greater activation of the right DLM corresponding to yaw rotation to the right. These results are consistent with the flapping counter torque (FCT) damping model and its supposed implications for neuromuscular control of simple yaw turns in flying animals. The extent to which this first order control of yaw turns applies to more complex maneuvers is unknown; we are developing a next-generation moth-portable EMG recording system which will facilitate recording of more complex behaviors such as combination yaw, pitch, and roll maneuvers.