Flies have remarkable vision. Their compound eyes are superbly adapted to their high-speed lifestyle. But what effect does a fly's motion have on the way the insect processes visual information? Ronny Rosner, Martin Egelhaaf, and Anne-Kathrin Warzecha from the Universität Bielefeld, Germany, explain that an insect's nervous system can be in a completely different state when it is immobile and when it is active and that this may affect the way that sensory information is processed. Knowing the role of lobula plate tangential cells in flight and head control, due to processing the moving surroundings' visual information, the trio decided to find out what effect the insect's movement has on the way that the cells process visual information ().
Allowing tethered flies to beat their halteres (hind wings that have evolved into moving stumps) as if the insects were walking or flying, the team recorded the electrical activity from the lobula plate tangential cells in response to images of bright and dim dots and blank screens. The team found that the flies' lobula plate tangential cells generated membrane potential changes when it was dark and the halteres were active: so activity does seem to modify the lobula plate tangential cells' output. And when the team played images of dim and bright dots to the flies, haltere activity enhanced the lobula plate tangential cells' membrane potentials, especially when the images were dim. So the flies' activity levels do affect their ability to process visual information, and Rosner and his colleagues suspect that this could allow the flies to respond faster when moving around.
