“Peak-Splitting”: Intensity Effects in Cochlear Afferent Responses to Low Frequency Tones

  • Mario A. Ruggero
  • Nola C. Rich
Part of the NATO ASI Series book series (NSSA)


In 1972, Kiang and Moxon noted that a notch can sometimes be measured in the rate-intensity function of cochlear-afferent responses to tones over restricted ranges of high intensities. It has been subsequently shown that, for low-frequency tones, the notch is found in association with bimodality of period histograms (“peak splitting”) and/or with a rapid shift in response phase (Gifford and Guinan, 1983; Kiang, 1984). In the present paper we present preliminary results from a systematic study of the intensity dependence of the magnitude and phase of responses of chinchilla cochlear afferents to low-frequency tones. Low-frequency stimuli are used to facilitate precise timing of the excitation of cochlear afferents relative to basilar membrane (BM) motion (Ruggero and Rich, 1987; Ruggero et al., 1986b). Our present findings, for responses to 200 – 600 Hz tones, agree with and extend our previous results for 100 Hz tones (Ruggero and Rich, 1988): within each stimulus cycle, there appear to exist two distinct preferred times for inner hair cell (IHC) excitation of cochlear afferents. Relative to BM motion, one corresponds to displacement or velocity toward scala tympani (ST) and the other is synchronous with maximal velocity toward scala vestibuli (SV). Which of these two response phases predominates depends on cochlear location (or, equivalently, characteristic frequency: CF) and on stimulus level, but does not depend significantly on stimulus frequency.


Hair Cell Basilar Membrane Peak Splitting Inner Hair Cell Scala Tympani 
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  1. Cody, A.R., Mountain, D.C. and Russell, I.J. (1986) Acoustically evoked potentials in the basal turn of the guinea pig cochlea. In: IUPS Satellite Symposium on Hearing, Univ. of California, San Francisco, p. 24.Google Scholar
  2. Dallos, P. (1983) Some electrical circuit properties of the organ of Corti. I. Analysis without reactive elements. Hear. Res. 12, 89–119.PubMedCrossRefGoogle Scholar
  3. Dallos, P. (1985) Response characteristics of mammalian cochlear hair cells. J. Neurosci. 5, 1591–1608.PubMedGoogle Scholar
  4. Dallos, P., Cheatham, M.A. and Oesterle, E. (1986) Harmonic components in hair cell responses. In: Auditory Frequency Selectivity (Eds: Moore, B.C.J. and Patterson, R.D.) Plenum, London, pp. 73–80.Google Scholar
  5. Gifford, M.L. and Guinan, Jr., J.J. (1983) Effects of crossed-olivocochlear-bundle stimulation on cat auditory nerve fiber responses to tones. J. Acoust. Soc. Am. 74, 115–123.PubMedCrossRefGoogle Scholar
  6. Kiang, N.Y.S. (1984) Peripheral neural processing of auditory information. In: Handbook of Physiology. The Nervous System. Sensory Processes. (Ed: Darian-Smith, I.) American Physiol. Soc., Bethesda, MD, pp. 639–674.Google Scholar
  7. Kiang, N.Y.S. and Moxon, E.C. (1972) Physiological considerations in artificial stimulation of the inner ear. Ann. Otol. Rhinol. Laryngol. 81, 714–730.PubMedGoogle Scholar
  8. Nuttall, A.L., Brown, M.C., Masta, R.I. and Lawrence, M. (1981) Inner hair cell responses to the velocity of basilar membrane motion in the guinea pig. Brain Res. 211, 171–174.PubMedCrossRefGoogle Scholar
  9. Ruggero, M.A. and Rich, N.C. (1983) Chinchilla auditory-nerve responses to low-frequency tones. J. Acoust. Soc. Am. 73, 2096–2108.PubMedCrossRefGoogle Scholar
  10. Ruggero, M.A. and Rich, N.C. (1987) Timing of spike initiation in cochlear afferents: dependence on site of innervation. J. Neurophysiol. 58, 379–403.PubMedGoogle Scholar
  11. Ruggero, M.A. and Rich, N.C. (1988) Responses of cochlear afferents to low-frequency tones: intensity dependence. In: Auditory Pathway — Structure and function (Eds: Syka, J. and Popelar, J.) Plenum, N.Y., in press.Google Scholar
  12. Ruggero, M.A., Robles, L. and Rich, N.C. (1986a) Cochlear microphonics and the initiation of spikes in the auditory nerve: correlation of single-unit data with neural and receptor potentials recorded from the round window. J. Acoust. Soc. Am. 79, 1491–1498.PubMedCrossRefGoogle Scholar
  13. Ruggero, M.A., Robles, L. and Rich, N.C. (1986b) Basilar membrane mechanics at the base of the chinchilla cochlea. II. Responses to low-frequency tones and relationship to microphonics and spike initiation in the VIII Nerve. J. Acoust. Soc. Am. 80, 1375–1383.PubMedCrossRefGoogle Scholar
  14. Russell, I.J. and Sellick, P.M. (1983) Low-frequency characteristics of intracellularly recorded potentials in guinea-pig cochlear hair cells. J. Physiol. (Lond.) 338, 179–206.Google Scholar
  15. Sellick, P.M., Patuzzi, R and Johnstone, B.M. (1982) Modulation of responses of spiral ganglion cells in the guinea pig cochlea by low frequency sound. Hear. Res. 7, 199–221.PubMedCrossRefGoogle Scholar
  16. Zwislocki, J.J. (1986) Comments on “Basilar membrane motion and spike initiation in the cochlear nerve” (Ruggero, M.A., Robles, L., Rich, N.C. and Costalupes, JA). In: Auditory Frequency Selectivity (Eds: Moore, B.C.J. and Patterson, R.D.) Plenum, London, p. 197.Google Scholar

Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • Mario A. Ruggero
    • 1
  • Nola C. Rich
    • 1
  1. 1.Department of OtolaryngologyUniversity of MinnesotaMinneapolisUSA

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