Abstract
In Drosophila melanogaster, hearing is supported by mechanosensory neurons transducing sound-induced vibrations of the antenna. It is shown here that these neurons additionally generate motions that mechanically drive the antenna and tune it to relevant sounds. Motion generation in the Drosophila auditory system is betrayed by the auditory mechanics; the antenna of the fly nonlinearly alters its tuning as stimulus intensity declines and oscillates spontaneously in the absence of sound. The susceptibility of auditory motion generation to mechanosensory mutations shows that motion is generated by mechanosensory neurons. Motion generation depends on molecular components of the mechanosensory transduction machinery (NompA, NompC, Btv, and TilB), apparently involving mechanical activity of ciliated dendrites and microtubule-dependent motors. Hence, in analogy to vertebrate hair cells, the mechanosensory neurons of the fly serve dual, transducing, and actuating roles, documenting a striking functional parallel between the vertebrate cochlea and the ears of Drosophila.
