7 research outputs found
Simulation of the Response of the Inner Hair Cell Stereocilia Bundle to an Acoustical Stimulus
Mammalian hearing relies on a cochlear hydrodynamic sensor embodied in the inner
hair cell stereocilia bundle. It is presumed that acoustical stimuli induce a
fluid shear-driven motion between the tectorial membrane and the reticular
lamina to deflect the bundle. It is hypothesized that ion channels are opened by
molecular gates that sense tension in tip-links, which connect adjacent stepped
rows of stereocilia. Yet almost nothing is known about how the fluid and bundle
interact. Here we show using our microfluidics model how each row of stereocilia
and their associated tip links and gates move in response to an acoustical input
that induces an orbital motion of the reticular lamina. The model confirms the
crucial role of the positioning of the tectorial membrane in hearing, and
explains how this membrane amplifies and synchronizes the timing of peak tension
in the tip links. Both stereocilia rotation and length change are needed for
synchronization of peak tip link tension. Stereocilia length change occurs in
response to accelerations perpendicular to the oscillatory fluid shear flow.
Simulations indicate that nanovortices form between rows to facilitate diffusion
of ions into channels, showing how nature has devised a way to solve the
diffusive mixing problem that persists in engineered microfluidic devices