Tripolar configuration and pulse shape in cochlear implants reduce channel interactions in the temporal domain

Gunnar L. Quass, Andrej Kral

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
3 Downloads (Pure)

Abstract

The present study investigates effects of current focusing and pulse shape on threshold, dynamic range, spread of excitation and channel interaction in the time domain using cochlear implant stimulation. The study was performed on 20 adult guinea pigs using a 6-channel animal cochlear implant, recording was performed in the auditory midbrain using a multielectrode array. After determining the best frequencies for individual recording contacts with acoustic stimulation, the ear was deafened and a cochlear implant was inserted into the cochlea. The position of the implant was controlled by x-ray. Stimulation with biphasic, pseudomonophasic and monophasic stimuli was performed with monopolar, monopolar with common ground, bipolar and tripolar configuration in two sets of experiments, allowing comparison of the effects of the different stimulation strategies on threshold, dynamic range, spread of excitation and channel interaction. Channel interaction was studied in the temporal domain, where two electrodes were activated with pulse trains and phase locking to these pulse trains in the midbrain was quantified. The results documented multifactorial influences on the response properties, with significant interaction between factors. Thresholds increased with increasing current focusing, but decreased with pseudomonophasic and monophasic pulse shapes. The results documented that current focusing, particularly tripolar configuration, effectively reduces channel interaction, but that also pseudomonophasic and monophasic stimulation and phase duration intensity coding reduce channel interactions.

Original languageEnglish
Article number108953
Pages (from-to)1-16
Number of pages16
JournalHearing Research
Volume443
Early online date19 Jan 2024
DOIs
Publication statusPublished - 1 Mar 2024

Bibliographical note

Copyright the Author(s) 2024. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Channel interactions
  • Spread of excitation
  • Duration coding
  • Polarity
  • Pseudomonophasic pulse
  • Monophasic pulse
  • Common ground
  • Bipolar

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