Midbrain responses to micro-stimulation of the cochlea using high density thin-film arrays

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• 作者：B.J. Allitt^a ; ^b ; S.J. Morgan^a ; ^b ; S. Bell^a ; ^c ; D.A.X. Nayagam^d ; B. Arhatari^e ; G.M. Clark^a ; ^b ; A.G. Paolini^a ; ^b ; ^{a.paolini@latrobe.edu.au}
• 关键词：CF ; Characteristic Frequency ; CI ; Cochlear Implant ; CIC ; Central Nucleus of the Inferior Colliculus ; CT ; Computed Tomography ; HDA ; High Density Electrode Array ; OCF ; Octaves Off Characteristic Frequency ; PSTH ; Post Stimulus Time Histogram
• 刊名：Hearing Research
• 出版年：2012
• 期刊代码：111_03785955
• 类别：med
• 出版时间：May, 2012
• 卷：287
• 期：1-2
• 页码：30-42
• 文件大小：1367 K

摘要

A broader activation of auditory nerve fibres than normal using a cochlear implant contributes to poor frequency discrimination. As cochlear implants also deliver a restricted dynamic range, this hinders the ability to segregate sound sources. Better frequency coding and control over amplitude may be achieved by limiting current spread during electrical stimulation of the cochlea and positioning electrodes closer to the modiolus. Thin-film high density microelectrode arrays and conventional platinum ring electrode arrays were used to stimulate the cochlea of urethane-anaesthetized rats and responses compared. Neurophysiological recordings were taken at 197 multi-unit clusters in the central nucleus of the inferior colliculus (CIC), a site that receives direct monaural innervation from the cochlear nucleus. CIC responses to both the platinum ring and high density electrodes were recorded and differences in activity to changes in stimulation intensity, thresholds and frequency coding of neural activation were examined. The high density electrode array elicited less CIC activity at nonspecific frequency regions than the platinum ring electrode array. The high density electrode array produced significantly lower thresholds and larger dynamic ranges than the platinum ring electrode array when positioned close to the modiolus. These results suggest that a higher density of stimulation sites on electrodes that effectively 鈥榓im鈥?current, combined with placement closer to the modiolus would permit finer control over charge delivery. This may equate to improved frequency specific perception and control over amplitude when using future cochlear implant devices.