Mathematical model of the auditory nerve response to stimulation by a micro‐machined cochlea. (7th January 2021)

• Record Type: Journal Article
• Authors: Yamazaki, Hiroki; Tsuji, Tetsuro; Doi, Kentaro; Kawano, Satoyuki
• Is Part Of: International journal for numerical methods in biomedical engineering. Volume 37:Number 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-07
• Subjects: cochlear implant -- feedback control -- fully implantable device -- piezoelectric material; Biomedical engineering -- Periodicals; Imaging systems in medicine -- Periodicals; Numerical analysis -- Periodicals; Engineering mathematics -- Periodicals; 610.28
• DOI: 10.1002/cnm.3430
• Languages: English
• ISSNs: 2040-7939

Abstract

Abstract: We report a novel mathematical model of an artificial auditory system consisting of a micro‐machined cochlea and the auditory nerve response it evokes. The modeled micro‐machined cochlea is one previously realized experimentally by mimicking functions of the cochlea [Shintaku et al, Sens. Actuat . 158 (2010) 183–192; Inaoka et al, Proc. Natl. Acad. Sci. USA 108 (2011) 18390–18395]. First, from the viewpoint of mechanical engineering, the frequency characteristics of a model device were experimentally investigated to develop an artificial basilar membrane based on a spring–mass–damper system. In addition, a nonlinear feedback controller mimicking the function of the outer hair cells was incorporated in this experimental system. That is, the developed device reproduces the proportional relationship between the oscillation amplitude of the basilar membrane and the cube root of the sound pressure observed in the mammalian auditory system, which is what enables it to have a wide dynamic range, and the characteristics of the control performance were evaluated numerically and experimentally. Furthermore, the stimulation of the auditory nerve by the micro‐machined cochlea was investigated using the present mathematical model, and the simulation results were compared with our previous experimental results from animal testing [Shintaku et al, J. Biomech. Sci. Eng . 8 (2013) 198–208]. The simulation results were found to be in reasonably good agreement with those from the previous animal test; namely, there exists a threshold at which the excitation of the nerve starts and a saturation value for the firing rate under a large input. The proposed numerical model was able to qualitatively reproduce the results of the animal test with the micro‐machined cochlea and is thus expected to guide the evaluation of micro‐machined cochleae for future animal experiments. Abstract : An auditory nerve response to stimulation by a micro‐machined cochlea is analyzed with a spring‐mass‐damper system and a Hodgkin‐Huxley (HH) model. The mechanical system involving a feedback control, which mimics the function of the outer hair cells, numerically and experimentally reproduces the oscillation characteristics of the mammalian basilar membrane. Furthermore, a nerve stimulated by the micro‐machined cochlea is analyzed with the HH model, and it is found that the numerical results are in qualitative agreement with our previous animal test.