Evidence for presynaptic facilitation in primary cochlear afferent neurons

J. H. Siegel*, E. M. Relkin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Evidence for presynaptic facilitation was sought in the discharge patterns of single units in the chinchilla cochlear nerve. Pairs of acoustic clicks, separated by a variable interval, were delivered and spike discharge times stored for offline analysis. By choosing an appropriate binwidth (5 ms) and collecting data only from units with high characteristic frequencies (CF) the response to each click was contained in a single bin. The ratio of spike counts in the bins containing the responses to the two clicks was computed. For units with low spontaneous rates (SR) of discharge (SR < 8/s), an enhancement of the response to the second click was seen for low stimulus levels. As the stimulus level was raised, the response to the second click became reduced, presumably because of adaptation to the first click. Units with high (SR > 15 spikes/s) seldom exhibited enhancement of the response to the second click. The results are explained with a conceptual model in which two processes, depletion and facilitation decay exponentially following a stimulus. Since the two processes have opposite influences on the rate of transmitter release, the magnitudes of both processes may be underestimated by observing their net effect.

Original languageEnglish (US)
Pages (from-to)169-177
Number of pages9
JournalHearing research
Issue number2-3
StatePublished - 1987


  • Auditory nerve
  • Facilitation
  • Synaptic transmission

ASJC Scopus subject areas

  • Sensory Systems


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