Stages of degradation of timing information in the cochlea: A comparison of hair-cell and nerve-fiber responses in the alligator lizard

Responses to clicks and tone bursts of hair cells and nerve fibers in the free-standing region of the alligator lizard cochlea were compared. The objective was to determine the extent to which the hair-cell processes that produce the receptor potential are also responsible for the attenuation of the synchronized responses of nerve fibers. The AC component of the receptor potential of these hair cells has a high-frequency attenuation of 20 dB/decade [Holton and Weiss (1983) J. Physiol. 345, 205-240], whereas the synchronized response of cochlear neurons is attenuated at a rate of least 80 dB/decade [Rose and Weiss (1988) Hear. Res. 33, 151-166]. Therefore, the processes that link the receptor potential to the nerve discharge act as a lowpass filter with a high-frequency attenuation of at least 60 dB/decade. This could be obtained from a cascade of at least three first-order lowpass filter processes.

[1]  M J Mulroy,et al.  Intracellular responses to acoustic clicks in the inner ear of the alligator lizard. , 1974, The Journal of the Acoustical Society of America.

[2]  A. Palmer,et al.  Phase-locking in the cochlear nerve of the guinea-pig and its relation to the receptor potential of inner hair-cells , 1986, Hearing Research.

[3]  B. Hille.  Ionic channels of excitable membranes , 2001 .

[4]  A. J. Hudspeth,et al.  Voltage- and ion-dependent conductances in solitary vertebrate hair cells , 1983, Nature.

[5]  J. Goldberg,et al.  Response of binaural neurons of dog superior olivary complex to dichotic tonal stimuli: some physiological mechanisms of sound localization. , 1969, Journal of neurophysiology.

[6]  P M Sellick,et al.  Low‐frequency characteristics of intracellularly recorded receptor potentials in guinea‐pig cochlear hair cells. , 1983, The Journal of physiology.

[7]  Richard S Lewis.  The Ionic Basis of Frequency Selectivity in Hair Cells of the Bullfrog's Sacculus , 1985 .

[8]  T. F. Weiss,et al.  Receptor potentials of lizard hair cells with free‐standing stereocilia: responses to acoustic clicks. , 1983, The Journal of physiology.

[9]  R. Zucker,et al.  Mechanism of transmitter release: voltage hypothesis and calcium hypothesis. , 1986, Science.

[10]  T. F. Weiss.  Relation of receptor potentials of cochlear hair cells to spike discharges of cochlear neurons. , 1984, Annual review of physiology.

[11]  T Holton,et al.  Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea. , 1983, The Journal of physiology.

[12]  P M Sellick,et al.  Intracellular studies of hair cells in the mammalian cochlea. , 1978, The Journal of physiology.

[13]  Robert G. Turner,et al.  Physiology and Bioacoustics in Reptiles , 1978 .

[14]  M. Kuno,et al.  Quantal analysis of a decremental response at hair cell‐afferent fibre synapses in the goldfish sacculus. , 1982, The Journal of physiology.

[15]  T Holton,et al.  Receptor potentials of lizard cochlear hair cells with free‐standing stereocilia in response to tones. , 1983, The Journal of physiology.

[16]  M. Kuno.  Adaptive changes in firing rates in goldfish auditory fibers as related to changes in mean amplitude of excitatory postsynaptic potentials. , 1983, Journal of neurophysiology.

[17]  Frequency dependence of synchronization of cochlear nerve fibers in the alligator lizard: Evidence for a cochlear origin of timing and non-timing neural pathways , 1988, Hearing Research.

[18]  T. Furukawa,et al.  Adaptive rundown of excitatory post‐synaptic potentials at synapses between hair cells and eight nerve fibres in the goldfish. , 1978, The Journal of physiology.