. Normal behavior and spatial orientation depend upon vestibular signals from the inner ear. There are two major subdivisions of the vestibular periphery: semicircular canals and otoconial organs. The former have been intensively studied. Otoconial organs are much less well understood, even though studies of central vestibular processing increasingly highlight their importance in control of posture, gaze, spatial orientation, and vegetative functions. Thus, there is a pressing need to understand this important subdivision of the labyrinth. We propose to address this need by analyzing the mechanical and biophysical origins of signals from a major otoconial organ, the utricle. Our experimental preparation is a turtle, one of the premier model systems for analyses of peripheral auditory and vestibular mechanisms. This multidisciplinary initiative analyzes utricular mechanisms at levels from behavior to cellular modeling. It builds on results from our current studies of biomechanics, which have yielded the most detailed data base on the structure and mechanics of the utricle available for any vertebrate.
Aim 1 uses high-speed video recording and NMR images of the labyrinth to quantify the stimuli that utricular hair cells are exposed to in freely behaving animals.
Aim 2 and Aim 3 combine experimental mechanics with biophysical and computational analyses to characterize important mechanical and hair cell responses to these stimuli.
Aim 4 uses morphophysiology, information analysis, and modeling to quantify the resulting afferent signals and their information content, contrast these signals with hair cell responses to the same stimuli, and test hypotheses about the origins of signal diversity in utricular afferents. Thus, the proposed research continues our efforts to build the first detailed, quantitative description of the mechanisms that shape utricular signals to the CMS. Relevance. Vestibular dysfunction is a common cause of physician visits. It can be particularly disabling, and vestibular deficits are thus a significant medical, social, and financial concern. In spite of its importance, the vestibular system, and otoconial organs in particular, are far less well understood than other sensory systems. We need new knowledge of otoconial organ function to improve diagnosis and treatment strategies. By contributing to this knowledge, the proposed research is directly relevant to the mission of the NIDCD.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Auditory System Study Section (AUD)
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Cyr, Janet
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Ohio University Athens
Schools of Arts and Sciences
United States
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Blob, Richard W; Mayerl, Christopher J; Rivera, Angela R V et al. (2016) ""On the Fence"" versus ""All in"": Insights from Turtles for the Evolution of Aquatic Locomotor Specializations and Habitat Transitions in Tetrapod Vertebrates. Integr Comp Biol 56:1310-1322
Huwe, J A; Logan, G J; Williams, B et al. (2015) Utricular afferents: morphology of peripheral terminals. J Neurophysiol 113:2420-33
Jones, Timothy A; Lee, Choongheon; Gaines, G Christopher et al. (2015) On the high frequency transfer of mechanical stimuli from the surface of the head to the macular neuroepithelium of the mouse. J Assoc Res Otolaryngol 16:189-204
Dunlap, M D; Grant, J W (2014) Experimental measurement of utricle system dynamic response to inertial stimulus. J Assoc Res Otolaryngol 15:511-28
Davis, J L; Grant, J W (2014) Turtle utricle dynamic behavior using a combined anatomically accurate model and experimentally measured hair bundle stiffness. Hear Res 318:37-44
Rivera, Angela R V; Rivera, Gabriel; Blob, Richard W (2013) Forelimb kinematics during swimming in the pig-nosed turtle, Carettochelys insculpta, compared with other turtle taxa: rowing versus flapping, convergence versus intermediacy. J Exp Biol 216:668-80
Rivera, Angela R V; Blob, Richard W (2013) Forelimb muscle function in pig-nosed turtles, Carettochelys insculpta: testing neuromotor conservation between rowing and flapping in swimming turtles. Biol Lett 9:20130471
Spoon, Corrie; Grant, Wally (2013) Biomechanical measurement of kinocilium. Methods Enzymol 525:21-43
Rivera, Angela R V; Davis, Julian; Grant, Wally et al. (2012) Quantifying utricular stimulation during natural behavior. J Exp Zool A Ecol Genet Physiol 317:467-80
Dunlap, M D; Spoon, C E; Grant, J W (2012) Experimental measurement of utricle dynamic response. J Vestib Res 22:57-68

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