A Computational Study into the Effect of Structure and Orientation of the Red Ear Slider Turtle Utricle on Hair Bundle Stimulus

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dc.contributor.authorDavis, Julian Lyen
dc.contributor.committeechairGrant, John Wallaceen
dc.contributor.committeememberWest, Robert L. Jr.en
dc.contributor.committeememberPeterson, Ellengene H.en
dc.contributor.committeememberCotton, John R.en
dc.contributor.committeememberBatra, Romesh C.en
dc.contributor.departmentEngineering Science and Mechanicsen
dc.date.accessioned2014-03-14T20:19:46Zen
dc.date.adate2007-12-28en
dc.date.available2014-03-14T20:19:46Zen
dc.date.issued2007-11-30en
dc.date.rdate2007-12-28en
dc.date.sdate2007-12-04en
dc.description.abstractThe vestibular system consists of several organs that contribute to ones sense of balance. One set of organs, otoconial organs, have been shown to respond to linear acceleration (1949). Hair bundles (and hair cells), which are the mechano-electric transducers found within otoconial organs, respond to displacement of the overlying otoconial membrane (OM). Structure, position and orientation of the OM within the head may influence the stimulus of hair bundles by changing the deformation characteristics of the OM. Therefore, studying the deformation characteristics of the OM with finite element models presents a unique advantage: the ability to study how different variables may influence the deformation of the OM. Previous OM models have ignored complicated OM geometry in favor of single degree of freedom (De Vries 1951)or distributed parameter models (Grant et al. 1984; Grant and Cotton 1990; Grant et al. 1994). Additionally, OMs have been modeled considering three dimensional geometry (Benser et al. 1993; Kondrachuk 2000; 2001a), however OM layer thicknesses were assumed to be constant. Further, little research has investigated the effect of position and orientation of otoconial organs on the deformation of the OM (Curthoys et al. 1999), due to natural movement of the head. The effect of structure, position and orientation of the utricle of a red ear slider turtle on the stimulation of hair bundles in the OM is investigated here. Using confocal images, a finite element model of the utricle OM is constructed considering its full 3D geometry and varying OM layer thickness. How specific geometric variables, which are missing from other OM models, effect the deformation of the utricle OM is studied. Next, since hair bundles are part of the structure of the OM, their contribution to the deformation of the utricular OM is quantified. Then, using computed tomography of a turtle head and high speed video of turtle feeding strikes, acceleration at the utricle during natural motion is estimated. Finally, the effects of orientation of the utricle in the head on the stimulus of hair bundles within the organ is investigated. In summary, a model and methods are developed through which deformation of the turtle utricle OM through natural movements of the head may be studied. Variables that may contribute to utricle OM deformation are investigated. Utricle OM geometry, hair bundles, position and orientation all play a role in utricle OM deflection and therefore hair bundle stimulus. Their effects are quantified and their roles are discussed in this dissertation.en
dc.description.degreePh. D.en
dc.identifier.otheretd-12042007-130153en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12042007-130153/en
dc.identifier.urihttp://hdl.handle.net/10919/29926en
dc.publisherVirginia Techen
dc.relation.haspartJul_Davis_Dissertation_Final_ETD_1.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectUtricleen
dc.subjectFinite element methoden
dc.subjectComputed Tomographyen
dc.subjectAccelerationen
dc.titleA Computational Study into the Effect of Structure and Orientation of the Red Ear Slider Turtle Utricle on Hair Bundle Stimulusen
dc.typeDissertationen
thesis.degree.disciplineEngineering Science and Mechanicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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