Effects of biphasic current pulse frequency, amplitude, duration, and interphase gap on eye movement responses to prosthetic electrical stimulation of the vestibular nerve

Natan S. Davidovics, Gene Y. Fridman, Bryce Chiang, Charles C.Della Santina

Research output: Contribution to journalArticle


An implantable prosthesis that stimulates vestibular nerve branches to restore sensation of head rotation and vision-stabilizing reflexes could benefit individuals disabled by bilateral loss of vestibular (inner ear balance) function. We developed a prosthesis that partly restores normal function in animals by delivering pulse frequency modulated (PFM) biphasic current pulses via electrodes implanted in semicircular canals. Because the optimal stimulus encoding strategy is not yet known, we investigated effects of varying biphasic current pulse frequency, amplitude, duration, and interphase gap on vestibulo-ocular reflex (VOR) eye movements in chinchillas. Increasing pulse frequency increased response amplitude while maintaining a relatively constant axis of rotation. Increasing pulse amplitude (range 0-325μA) also increased response amplitude but spuriously shifted eye movement axis, probably due to current spread beyond the target nerve. Shorter pulse durations (range 28-340μs) required less charge to elicit a given response amplitude and caused less axis shift than longer durations. Varying interphase gap (range 25-175μs) had no significant effect. While specific values reported herein depend on microanatomy and electrode location in each case, we conclude that PFM with short duration biphasic pulses should form the foundation for further optimization of stimulus encoding strategies for vestibular prostheses intended to restore sensation of head rotation.

Original languageEnglish (US)
Article number5560867
Pages (from-to)84-94
Number of pages11
JournalIEEE Transactions on Neural Systems and Rehabilitation Engineering
Issue number1
StatePublished - Feb 1 2011



  • Electrical stimulation
  • interphase gap
  • neural
  • prosthesis
  • pulse duration
  • vestibular
  • vestibular implant

ASJC Scopus subject areas

  • Internal Medicine
  • Neuroscience(all)
  • Biomedical Engineering

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