Finite-element analysis of inner ear hair bundles: a parameter study of bundle mechanics

Inner ear hair cells have been identified as the sites of mechanoelectrical transduction from a mechanical event (e.g. hearing, motion) to an electrical event (e.g. neural response). Deflection of bundles of hair-like stereocilia extending from these cells has been associated with the transduction process. Stereocilia bundle structure and stiffness controls deflection and thus the fundamental sensitivity of the transduction process. The finite-element method was used along with analytical techniques to characterize individual stereocilium and stereocilia bundle stiffnesses. A three ‘stack’ bundle with a Young’s modulus of 3 GPa (F-actin protein) and Poisson’s ratio of 0.4 (nearly incompressible) resulted in a stiffness of K = 2.1 x 10⁻³ N/m. This value is within the range of experimentally determined stiffmesses. Tip-link and subapical band interconnecting structures each contribute significantly to bundle stiffness and each could act as the gating-spring in transduction models, which propose gating structures as a means of regulating ionic activity and therefore neural activity. Stiffness depends most strongly on individual stereocilium geometry and material description, tip-link orientation and material description, and stereocilia bundle width. Stiffness depends least on stereocilia height variations and subapical bands configuration. Linear analysis was reliable up to deflections of 3.5 um, the upper limit of physical response. Preliminary dynamic response indicates a natural frequency of 382 kHz for the vibration mode resembling physical deformation behavior. Future models should include hexagonal bundle arrangements, transversely isotropic stereocilia material descriptions, and viscoelastic tip-link behavior.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1993

Author dc:creator

• Duncan, Robert Keith

Chair dc:contributor.committeechair

• Grant, John Wallace

Committee members dc:contributor.committeemember

• Griffin, Odis Hayden Jr.
• Landgraf, Ronald W.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-09292009-020226

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/44930