Regensburg 2004 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 50: Poster Session "Biological Physics"
AKB 50.65: Poster
Freitag, 12. März 2004, 10:30–13:00, B
Spontaneous Oscillations by hair bundles from the vertebrate inner ear — •Björn Nadrowski1, Pascal Martin2, and Frank Jülicher1 — 1Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, D-01187 Dresden, Germany — 2Laboratoire Physico-Chimie Curie, Unité Mixte de Recherche 168, Institut Curie, 26 rue d’Ulm, F-75248 Paris Cedex 05, France
Hearing relies on active filtering to achieve exquisite sensitivity and sharp frequency selectivity. In a quiet environment, the ears of many vertebrates emit one to several tones. These spontaneous otoacoustic emissions, the most striking manifestation of the inner ear’s active process, must result from self-sustained mechanical oscillations of aural constituents. As early as 1948, Thomas Gold proposed that the ear contains an active amplifier, and predicted oto-acoustic emissions for malfunctioning, i.e. over-amplified ears. It has recently been shown that the mechanosensitive hair bundles of vestibular cells from the frog ear have the ability to oscillate spontaneously. This spontaneous oscillation leads to frequency-selective amplification and nonlinearity in the bundles mechanical response. We discuss the physical principles behind detection based on critical oscillation as well as specific mechanisms that can lead to oscillations and active behaviors by hair bundles. A simple theoretical description of the hair bundle is presented, and its implications are studied. The hair bundles non-linear response to mechanical stimuli is described. We pay special attention to the role of noise in the system.