Psst. This fly's ears can rival a cat's.Owls and cats turn out to have a not-so-charismatic rival in their much-admired ability to pinpoint a sound's origin: a sound-tracking parasitic fly. The flies are too tiny for the usual direction-fixing physiology to work, says Andrew C. Mason of the University of Toronto Research at the University of Toronto has been responsible for the world's first electronic heart pacemaker, artificial larynx, single-lung transplant, nerve transplant, artificial pancreas, chemical laser, G-suit, the first practical electron microscope, the first cloning of T-cells, at Scarborough. Yet an unusual eardrum ear·drum n. The thin, semitransparent, oval-shaped membrane that separates the middle ear from the external ear. Also called drum, drumhead, drum membrane, myringa, myrinx, tympanic membrane, structure allows Ormia ochracea to pinpoint a sound's source to within 2 compass degrees, Mason reported this week in New Orleans at the meeting of the Society for Neuroscience For other uses, see SFN (disambiguation). The Society for Neuroscience (SfN) is a professional society for basic scientists and physicians around the world whose research is focused on the study of the brain and nervous system. . Neuroscientists discovered the fly's unusual ear structure several years ago. "What we're talking about now is how well it works," Mason says. "In terms of directional hearing, the flies are as good as any system ever studied." Before the discovery of the structure, neuroscientists had thought that the flies' tiny size ruled out the directional-tracking method that bigger animals use: comparing a sound's loudness and arrival time at the two ears. It turns out, however, that the fly's eardrums are connected. Sound hitting the drum nearer the source kicks up a response in the other one almost instantaneously. The transferred vibration in the far eardrum interferes with its direct reaction to the sound. The stronger vibration, therefore, marks the ear closer to the sound. The flies manage such keen source tracking with a remarkably stripped-down nervous system. A person pools responses from several thousand sensory cells in each ear, yet O. ochracea has only about 100 such cells per ear. Most flies don't have any hearing systems, Mason notes. Yet the female O. ochracea follows cricket chirps to find hosts for the parasitic larvae Larvae, in Roman religion Larvae: see lemures. that she bears. Mason measured auditory talent by tethering flies to a modified computer trackball A stationary pointing device that contains a movable ball rotated with the fingers or palm. From one to three keys are located in various positions depending on the unit. Years ago, Kensington Microware popularized the trackball with its Turbo Mouse for the Macintosh. that served as a treadmill. As Mason broadcast cricket chirps from different locations, a computer analyzed the fly's motions. In some experiments, Mason also measured nerve impulses triggered by the chirps. The fly's novel ear will open many new directions for hearing research, predicts another Ormia researcher, Daniel Robert of the Universitat Zurich in Switzerland. Researchers at the State University of New York (body) State University of New York - (SUNY) The public university system of New York State, USA, with campuses throughout the state. in Binghamton, for instance, are trying to model a small direction-tracking microphone after the fly's ears. That could prove useful for designing hearing aids Hearing Aids Definition A hearing aid is a device that can amplify sound waves in order to help a deaf or hard-of-hearing person hear sounds more clearly. . |
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