Determinants of the spectrum of the neural electrical activity at the round window

Transmitter release and neural depolarisation

R. B. Patuzzi*, D. J. Brown, C. M. McMahon, A. F. Halliday

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In this paper we summarise the changes we have observed in the electrical activity at the round window (RW) of guinea pigs during transient cooling of the RW or cochlear nucleus (CN), transient hypoxia, low frequency acoustic biasing, ablation of the CN, and DC current injection into the basal cochlear turn. We have measured the compound action potential (CAP), the spectrum of the average CAP waveform (SAW) evoked by brief tone-bursts, and the spectrum of the neural noise (SNN). We discuss how the changes we have observed can be understood in terms of changes in transmitter release from inner hair cells (that controls stochastic neural firing), or changes in the membrane potential of the primary afferent neurones (that controls the neural firing waveshape and the spectral content of the SAW and SNN). We note that changes in sound intensity produce a simple increase in the stochastic release of transmitter from inner hair cells, without much change in the waveform of the neural response, but manipulations of the auditory brainstem, cooling and current injection all appear to alter neural firing rate and the neural response waveform, producing a baseline shift in the CAP and changes in 1000 Hz peak and low frequency content of the SAW and SNN. We also discuss the use of the CAP, SAW and SNN as an indication of cochlear and auditory brainstem neural activity.

Original languageEnglish
Pages (from-to)87-108
Number of pages22
JournalHearing Research
Volume190
Issue number1-2
DOIs
Publication statusPublished - Apr 2004
Externally publishedYes

Keywords

  • CAP, compound action potential
  • CM, cochlear microphonic
  • CN, cochlear nucleus
  • Cochlea
  • Cochlear nucleus
  • Guinea pig
  • Lateral olivo-cochlear efferent neuron
  • Round window compound action potential
  • Spectrum of the averaged waveform

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