Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 21: Neurobiophysics and Sensory Transduction
BP 21.2: Vortrag
Mittwoch, 24. März 2010, 14:30–14:45, H43
Coupling a sensory hair-cell bundle to cyber clones enhances nonlinear amplification — •Kai Dierkes1, Jérémie Barral2, Benjamin Lindner1, Frank Jülicher1, and Pascal Martin2 — 1MPIPKS, Dresden, Germany — 2Institut Curie, Paris, France
The mammalian cochlea's performance is marked by its exquisite sensitivity to weak amplitude stimuli, its sharp frequency selectivity and its wide dynamic range. It owes these abilities to a nonlinear process that actively boosts vibrations of the basilar membrane. Active hair bundle motility has been suggested to contribute to this cochlear amplifier. Indeed, hair bundles can actively oscillate and act as tuned nonlinear amplifiers. Their responsiveness, however, is limited by intrinsic fluctuations. Hair bundles typically are elastically coupled by overlying gelatinous membranes. In a recent theoretical work we have shown that elastic coupling of small groups of hair bundles could greatly enhance hair-bundle mediated amplification by means of a noise reduction effect (Dierkes et al., PNAS, 2008). Here we report on an experimental study for which we have interfaced dynamic force clamp performed on a hair bundle from the bullfrog's sacculus with real time stochastic simulations of a biophysical description of stochastic hair bundle dynamics. By means of this setup we could couple a hair bundle to two virtual neighbours, called cyber clones. We show that elastic coupling leads to synchronization and an increased coherence of spontaneous oscillations. Also, the sensitivity to weak driving is enhanced. Our results thus demonstrate the hair bundle's ability to team-up with other hair bundles to overcome the limitations of intrinsic noise.