The fruit fly (Drosophila) is a valuable genetic model for many diseases, including neurodegenerative ones such as Parkinson’s. But until now, its small size has made it difficult to measure physical motion and motor defects.
Researchers at Columbia University Medical Center have developed hardware, along with a software program called FlyWalker, that can measure a wide range of parameters such as the insect’s walking speed, distance walked, and gait pattern. The ability to quantify the fly’s walking behavior should add to scientists’ basic understanding of animal locomotion. It should also help them to discover subtle changes as Parkinson’s and other diseases progress over time.
César Mendes PhD, a postdoctoral fellow in the laboratory of Richard Mann, PhD, the Higgins Professor of Biochemistry and Molecular Biophysics, collaborated with Imre Bartos, PhD, and Szabolcs Márka, PhD, of Columbia’s Physics Department, to develop an optical touch sensor in which bursts of light are emitted when an object—here, a fly’s foot—touches a surface. These bursts of light are captured in real time with high-speed video imaging, to monitor the fly’s body and each of its six feet as it walks across the surface. They then use FlyWalker to analyze the data.
The researchers found that unlike a horse going from a walk to a trot at defined speeds, the fly doesn’t abruptly switch from one gait to another. It does, however, appear to modify its neural circuits depending on its speed. The research team also found that although the footprints of sensory-deprived flies, which had genetically lost their sense of proprioception, were less precisely aligned, the flies were still able to walk using a relatively normal gait. (Proprioception is one’s sense of the position and location of one’s bodily parts.) This suggests that proprioception is not essential for walking but does facilitate coordination.
The next step (no pun intended) is to combine this new method for analyzing locomotion with genetic tools available for studying the fruit fly, to further explore the role of motor neuron circuitry in walking.
“Quantification of gait parameters in freely walking wild type and sensory deprived Drosophila melanogaster” was published in eLife on January 8, 2013. It was also featured on Nature Medicine’s spoonful of medicine blog.