Rattay F, Tanzer T. Impact of electrode position on the dynamic range of a human auditory nerve fiber.
J Neural Eng 2022;
19. [PMID:
35105835 DOI:
10.1088/1741-2552/ac50bf]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 02/01/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE
Electrodes of a cochlear implant generate spikes in auditory nerve fibers (ANFs). While the insertion depth of each of the electrodes is linked to a frequency section of the acoustic signal, the amplitude of the stimulating pulses controls the loudness of the related frequency band. However, in comparison to acoustic stimulation the dynamic range of an electrically stimulated ANF is quite small.
APPROACH
The dynamic range of an electrically stimulated ANF is defined as the interval of stimulus amplitudes that causes firing probabilities between 10% and 90%. A compartment model that includes sodium ion current fluctuations as the stochastic key component for spiking was evaluated for different electrode placements and fiber diameters.
MAIN RESULTS
The dynamic range is reversely related to ANF diameter. An increased dynamic range is expected to improve the quality of auditory perception for cochlear implant users. Electrodes are often placed as close to the center axis of the cochlea as possible. The analysis of the simulated auditory nerve firing showed that this placement is disadvantageous for the dynamic range of a selected ANF.
SIGNIFICANCE
Five times larger dynamic ranges are expected for electrodes close to the terminal of the dendrite or at mid-dendritic placement as opposed to electrodes close to the modiolus.
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