Graeme Clark Collection

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Start date: 2000 × End date: 2009 × Subject: electrical stimulation × Subject: auditory nerve ×

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    Inner ear implants
    Clark, Graeme M. (Dekker, 2004)
    The cochlear implant is an electronic device that brings useful hearing to severely to profoundly deaf people through multiple-channel electrical stimulation of the auditory nerves in the inner ear. This is required if their inner ears are so badly damaged by injury and disease, or so inadequately developed, that they cannot provide sufficient hearing for communication, even when the sound is amplified with a hearing aid. By stimulating the nerve directly with patterns of electrical pulses, the implant bypasses the normal function of the sense organ of hearing in the inner ear to partially reproduce the coding of sound. It consists of a wearable speech processor that picks up sound with a microphone, analyzes the signal, and then sends it by radio waves to the implanted receiver stimulator, which decodes the message and stimulates the electrode wires inserted into the inner ear.
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    Advances in computational modelling of cochlear implant physiology and perception
    Bruce, Ian C. ; White, M. W. ; Irlicht, L. S. ; O'Leary, Stephen J. ; Clark, Graeme M. (IOS Press, 2001)
    Models of cochlear implant physiology and perception have historically utilized deterministic descriptions of auditory-nerve (AN) responses to electrical stimulation, which ignore stochastic activity present in the response. Physiological models of AN responses have been developed that do incorporate stochastic activity [8][13][14][27][38][39], but the consequences of stochastic activity for the perception of cochlear implant stimulation have not been investigated until recently [3]. Such an investigation is prompted by inaccuracies in predicting cochlear implant perception by deterministic models. For example, studies of single-fiber responses, where only an arbitrary deterministic measure of threshold is recorded, do not accurately predict perceptual threshold versus phase duration (strength-duration) curves for sinusoidal stimulation [24] or for pulsatile stimulation [25][26]. Furthermore, strength-duration curves of cochlear implant users are not well predicted by deterministic Hodgkin Huxley type models [25] [30].However, the complexity of previous stochastic physiological models has made the computation of responses for large numbers of fibers both laborious and time-consuming. Furthermore, the parameters of these models are often not easily matched to the fiber characteristics of the auditory nerve in humans or other mammals. This has prompted us to develop a simpler and more computationally efficient model of electrical stimulation of the auditory nerve [1][2][4] which is capable of direct and rapid prediction of perceptual data[3]