Phase-locking in the cochlear nerve of the guinea-pig and its relation to the receptor potential of inner hair-cells

Hear Res. 1986;24(1):1-15. doi: 10.1016/0378-5955(86)90002-x.


The high-frequency limit of phase-locking has been measured in fibres of the auditory nerve in the guinea-pig. It is shown that phase-locking begins to decline at about 600 Hz and is no longer detectable above 3.5 kHz which is about 1 octave lower than in the cat, squirrel monkey and some birds. Direct measurements of the cochlear afferent fibre synaptic delay are consistent with indirect estimates from phase-locking, both giving values of 0.7-0.8 ms. Measurements of the receptor potentials of inner hair-cells in the guinea pig cochlea indicate that as the stimulus frequency is increased there is a progressive decrease in the a.c. component compared to the steady depolarization. The cause of this decline is the low-pass filtering of the a.c. component by the hair-cell membrane. The cut-off and slope of the decline in the a.c. component is consistent with the suggestion that this process is the limiting factor in cochlear nerve fibre phase-locking. The implications of these findings for interspecies variation in phase-locking cut-off, for cochlear mechanisms and for the encoding of complex sounds are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Action Potentials
  • Afferent Pathways / physiology
  • Animals
  • Cochlea / physiology*
  • Cochlear Nerve / physiology*
  • Guinea Pigs
  • Membrane Potentials
  • Nerve Fibers / physiology
  • Sound*