As a fly flies through its environment, static objects produce moving images on its retina, and this optic flow is essential for steering and course corrections. Different types of rotation and translation produce unique flow fields, which fly brains are wired to identify. However, a feature of optic flow unique to translational motion is that adjacent images may move across the retina at different speeds, depending on their distance from the observer. Many insects take advantage of this depth cue, called motion parallax, to determine the distance to objects. We wanted to know if differential object speeds affect the corrective responses of fruit flies when they experience unplanned course deviations. We presented tethered flying flies with optic flow and measured their corrective responses to sideways perturbations of images with different relative forward speeds. We found that flying flies attend to the relative speed of dots during forward motion, and adjust their corrective responses to sideslip deviations depending on this cue. With no other distinguishing features (such as brightness or size), flies mounted a greater response to sideways deviations that were signaled by faster moving dots in the forward flow field, those that appeared radially closer by their speeds. This is consistent with the interpretation that fruit flies attend to seemingly nearer objects, and correct more strongly when they indicate a perturbation.
Keywords: Drosophila, vision, parallax, optomotor response, depth cue
Citation: Cabrera S and Theobald JC (2013) Flying fruit flies correct for visual sideslip depending on relative speed of forward optic flow. Front. Behav. Neurosci. 7:76. doi: 10.3389/fnbeh.2013.00076
Received: 04 March 2013; Accepted: 14 June 2013;
Published online: 02 July 2013.
Edited by:Shigeyoshi Itohara, RIKEN Brain Science Institute, Japan
Reviewed by:Kei Ito, University of Tokyo, Japan
Copyright © 2013 Cabrera and Theobald. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Jamie C. Theobald, Department of Biological Sciences, Florida International University, 11200 SW 8th Street, OE 167, Miami, FL 33199, USA e-mail: firstname.lastname@example.org