Rate-intensity-functions of pigeon auditory primary afferents

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Abstract

Rate-intensity-functions (RI-functions) were determined in 150 primary auditory afferents in anaesthetized pigeon. Acoustic stimulation was either at characteristic frequency (CF) or half an octave below or above CF. Stimulated at CF, 37% of the fibres showed saturating RI-functions, whereas 50% showed sloping and 13% straight RI-functions. In the sloping RI-functions, a bend was found about 20 dB above the fibres' thresholds. For non-CF stimuli, the general shape of the RI-functions remained constant. However, the maximum evoked discharge rates were lower for frequencies below CF and higher for frequencies above CF. The data show that a population of neurones, the sloping and straight ones, code stimulus intensities over a wide intensity range. In combination with the scatter of the thresholds, intensity ranges greater than 100 dB are conceivable. It was concluded that the nonlinearities found in pigeon are not caused by basilar membrane (BM) mechanics, rather an origin at the hair cell-afferent nerve fibre system has to be considered.

References (32)

  • T. Vossieck et al.

    The influence of dc polarization of the endocochlear potential on single fibre activity in the pigeon cochlear nerve

    Hear. Res.

    (1991)
  • I.M. Winter et al.

    Diversity of characteristic frequency rate-intensity functions in guinea pig auditory nerve fibres

    Hear. Res.

    (1990)
  • G.K. Yates et al.

    Basilar membrane nonlinearity determines auditory nerve rate-intensity functions and cochlear dynamic range

    Hear. Res.

    (1990)
  • D. Ding-Pfennigdorff

    Farbstoffmarkierungen identifizierter Neurone aus der Vogelcochlea

  • R.J. Dooling et al.

    Auditory intensity discrimination in the parakeet (Melopsittacus undulatus)

    J. Acoust. Soc. Am.

    (1975)
  • E. Grunwald et al.

    Auditory intensity discrimination in the pigeon (Columba livia) as measured by heart-rate conditioning

    Naturwissenschaften

    (1986)
  • Cited by (0)

    Preliminary results of this study were presented at the 21th Neurobiologentagung Göttingen 1993.

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