Electrically evoked compound action potentials of guinea pig and cat: Responses to monopolar, monophasic stimulation

Charles A. Miller*, Paul J. Abbas, Jay T. Rubinstein, Barbara K. Robinson, Akihiro J. Matsuoka, George Woodworth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


We recorded electrically evoked compound action potentials (EAPs) from guinea pigs and cats using monophasic current pulses delivered by a monopolar intracochlear electrode. By using simple stimuli, we sought results that could shed light on basic excitation properties of the auditory nerve. In these acute experiments, the recording electrode was placed directly on the auditory nerve. Responses to anodic and cathodic stimulus pulses were recorded separately to evaluate stimulus polarity effects. Several polarity- dependent properties were observed. Both EAP morphology and latency were polarity-dependent, with greater latencies for cathodic stimulation. Threshold stimulus level was also polarity-dependent, but in different directions in the two species: cats had lower cathodic thresholds while guinea pigs had lower anodic thresholds. We also observed that the slopes of the EAP amplitude-level functions depended upon stimulus polarity. In most cases where EAP saturation amplitude could be measured, that amplitude was similar for anodic and cathodic stimuli, suggesting that either stimulus polarity can recruit all fibers, or at least a comparable numbers of fibers. The common findings (e.g., EAP morphology and polarity-dependent latency) observed in these two species suggest results that can be extrapolated to responses obtained in humans, while the species-specific findings (e.g., dependence of threshold on polarity) may point to underlying anatomical differences that caution against overgeneralization across species. Some of our observations also bear upon hypotheses of how electrical stimuli may excite different sites on auditory nerve fibers.

Original languageEnglish (US)
Pages (from-to)142-154
Number of pages13
JournalHearing research
Issue number1-2
StatePublished - May 1998


  • Auditory nerve
  • Cat
  • Cochlear implant
  • Electrical stimulation
  • Guinea pig

ASJC Scopus subject areas

  • Sensory Systems


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