[Pathologic mechanoelectric transduction of outer hair cells as the cause of recruitment].
It is believed that the sound-induced travelling wave in the mammalian cochlea is enhanced and sharpened by a positive feedback mechanism. This causes the passive linear basilar membrane growth function to become non-linear. The present paper shows that nonlinear basilar membrane vibration is due to the nonlinear growth function of the receptor potential of outer hair cells, which can be described by a 2nd-order Boltzmann function. Since intensity coding in the inner ear depends on an interaction of nonlinear basilar membrane motion and nerve fibers with three different types of synaptic threshold and growth function, the process is directly dependent on an intact mechanoelectrical transduction of outer hair cells. According to the proposed model, a loss in efficiency of outer hair cell mechanoelectrical transduction must lead to both a reduction in gain (i.e., hearing loss) and a linearizing of the response. As a result, once above threshold, the changes of stereociliary displacement, basilar membrane displacement and neural firing rate per unit change of sound intensity must be larger than for the healthy cochlea with its compressive nonlinearity.
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Universitäts-HNO-Klinik Tübingen.
D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D001489:Basilar Membrane / Q000503:physiopathology; D002478:Cells, Cultured; D005246:Feedback / Q000502:physiology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000503:physiopathology*; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology*; D012001:Hyperacusis / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D008564:Membrane Potentials / Q000502:physiology; D008959:Models, Neurological; D009412:Nerve Fibers / Q000502:physiology; D014741:Video Recording
Pathologische mechanoelektrische Transduktion der äusseren Haarsinneszellen als Ursache für Rekruitment.