Affiliations: Department of Engineering Science and Mechanics, and School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
Correspondence:
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Corresponding author: John R. Cotton. Tel.: +1 540 231 7979; Fax: +1 540 231 4574; E-mail: jcotton@vt.edu
Abstract: A dynamic 3-D hair bundle model including inertia and viscous fluid drag effects based on the finite element method is presented. Six structural components are used to construct the hair bundle – kinocilium, stereocilia, upper lateral links, shaft links, tip links, and kinocilial links. Fluid drag is distributed on the surface of cilia columns. Bundle mechanics are analyzed under two distinct loading conditions: (1) drag caused by the shear flow of the surrounding endolymph fluid (fluid-forced), (2) a single force applied to the tip of the kinocilium (point-forced). A striolar and a medial extrastriolar vestibular hair cell from the utricle of a turtle are simulated. The striolar cell bundle shows a clear difference in tip link tension profile between fluid-forced and point-forced cases. When the striolar cell is fluid forced, it shows more evenly distributed tip link tensions and is far more sensitive, responding like an on/off switch. The extrastriolar cell does not show noticeable differences between the forcing types. For both forcing conditions, the extrastriolar cell responds serially – the nearest tip links to the kinocilium get tensed first, then the tension propagates to the farther tip links.
Keywords: Hair cell, tip link, fluid drag, finite element model
