Auditory Study| Question

1. Hair cells respond only to stimuli parallel to the hair bundle's axis of morphological symmetry.

-> how to operate parallelly each stereocilia direction, and tip link direction?

 

 

2. auditory systems average response over several cycles to improve its signal-to-noise ratio, the threshold of hearing corresponds to hair-bundle deflection of as little as +-0.3nm.

-> Who and How average?

The dynamics of coupled nonlinear oscillators have been extensively investigated because of their relevance in various fields of study (20,21). For the auditory system, several investigations suggest benefits of coupling on signal detection performed by groups of active, oscillatory hair bundles. Theoretical predictions reveal that a system of oscillating hair bundles with a large frequency dispersion may become quiescent under a sufficiently strong coupling, a phenomenon termed amplitude death (22,23). This regime shows a greatly enhanced signal/noise ratio in response to a driving force, making it an attractive alternative mechanism that the auditory system may utilize to achieve sensitivity in the presence of noise. Furthermore, coupling of unstable oscillators with a small difference in their characteristic frequencies reduces the effective noise level, resulting in more coherent autonomous oscillations as well as the enhanced quality factor in their response to a sinusoidal driving force (18,24, 25, 26). This has been experimentally demonstrated in a system of a small number of spontaneously oscillating hair bundles in a chemical environment that approximates the physiological conditions (27,28).

Dynamics of Mechanically Coupled Hair-Cell Bundles of the Inner Ear

 

3. When transduction current enters the channels, the ensuing change in stereocilia before it changes the potential at the base of the cell body and thus influences the rate of transmitter release. Because the stereocilia are short, however, their cable properties do not attenuate electric signals significantly.