AI Article Synopsis
- The inner ear of vertebrates detects sound through a network of sensory elements, notably the hair bundle made of stereocilia with ion channels that trigger electrical signals for hearing.
- Recent research by Kozlov et al. shows that the hair bundle dynamics occur in a subdiffusive manner at high frequencies, explained by the movement of a filament called the tip link.
- This paper proposes that the fluctuations of the tip link follow fractional Brownian motion, which aligns with experimental data and provides a potential explanation for its unique properties.
Article Abstract
The detection of sound signals in vertebrates involves a complex network of different mechano-sensory elements in the inner ear. An especially important element in this network is the hair bundle, an antenna-like array of stereocilia containing gated ion channels that operate under the control of one or more adaptation motors. Deflections of the hair bundle by sound vibrations or thermal fluctuations transiently open the ion channels, allowing the flow of ions through them, and producing an electrical signal in the process, eventually causing the sensation of hearing. Recent high frequency (0.1-10 kHz) measurements by Kozlov et al. [Proc. Natl. Acad. Sci. U.S.A. 109, 2896 (2012)] of the power spectrum and the mean square displacement of the thermal fluctuations of the hair bundle suggest that in this regime the dynamics of the hair bundle are subdiffusive. This finding has been explained in terms of the simple Brownian motion of a filament connecting neighboring stereocilia (the tip link), which is modeled as a viscoelastic spring. In the present paper, the diffusive anomalies of the hair bundle are ascribed to tip link fluctuations that evolve by fractional Brownian motion, which originates in fractional Gaussian noise and is characterized by a power law memory. The predictions of this model for the power spectrum of the hair bundle and its mean square displacement are consistent with the experimental data and the known properties of the tip link.
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| http://dx.doi.org/10.1063/1.4768902 | DOI Listing |
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