Ever photograph a moving object using a camera set at too slow a shutter speed? If so, then you know that the resulting image may be low contrast and blurry. Similar optical principles apply to biological visual systems. When the speed of retinal photoreceptors and/or neurons in the brain is not fast enough to overcome the relative velocity between the observer and the target, the visual image can become too blurred for the observer to recognize objects. Humans rarely experience this effect because we move slowly, but many animals move quickly and suffer motion blur during pursuit of targets. This project will investigate the visual and locomotory systems of fast-running, predatory tiger beetles that go blind while chasing prey and must stop briefly (tens of milliseconds) to re-localize the prey and then run again. The basic question is why does the beetle run faster than its eyes and brain can process target images? Dr. Gilbert will use a combination of 1) electrophysiological experiments on nerve cells at different levels in the beetle's visual system to test their response to moving targets, 2) behavioral studies of tethered beetles chasing computer generated, virtual reality images to quantify the effects of motion blur on pursuit tracking, and 3) computer modeling of the perception of the moving world viewed by a simulated beetle visual system to determine whether the beetle goes blind in all areas of the visual field or whether some running strategies may reduce blur in certain areas and allow continued tracking. By investigating an extreme biological example of the effects of motion blur on a tracking system, Dr. Gilbert will discover design principles about the nature of all visual systems, as well as provide insight into the limits of man-made machine vision systems and possible strategies for overcoming deleterious effects of motion blur. In terms of broader impacts related to education and nurturing of future scientists, the project will provide interdisciplinary training between engineering and biology for a post-doctoral fellow and undergraduate students.
