Genetic Dissection of Optomotor Behavior inDrosophila melanogasterStudies on Wild-Type and the Mutantoptomotor-blindH31

In stationary flight Drosophila melanogaster produces yaw torque in response to visual movement stimuli. The residual optomotor yaw torque response of the mutant optomotor-blindH31 (omb), which lacks the horizontal (HS) and vertical (VS) giant fibers in the lobula plate, differs from that of wild-type in several aspects: it is restricted to the frontal visual field, it is only elicited by front-to-back motion and appears to be mediated by a different set of elementary movement detectors (EMDs). Using a single black stripe as motion stimulus the torque response is, even in wild-type flies, dominated by the frontal visual field and by front-to-back motion. We thus propose that Drosophila's optomotor yaw control is organized as two partially parallel subunits. The component still displayed by omb is called "object response"; the component missing in the mutant (which is presumably mediated by the giant HS-cells in the wild-type) is called "large field response". Several properties of the object response are described.