Stimulus-timing-dependent modifications of rate-level functions in animals with and without tinnitus

J Neurophysiol. 2015 Feb 1;113(3):956-70. doi: 10.1152/jn.00457.2014. Epub 2014 Nov 12.


Tinnitus has been associated with enhanced central gain manifested by increased spontaneous activity and sound-evoked firing rates of principal neurons at various stations of the auditory pathway. Yet, the mechanisms leading to these modifications are not well understood. In a recent in vivo study, we demonstrated that stimulus-timing-dependent bimodal plasticity mediates modifications of spontaneous and tone-evoked responses of fusiform cells in the dorsal cochlear nucleus (DCN) of the guinea pig. Fusiform cells from sham animals showed primarily Hebbian learning rules while noise-exposed animals showed primarily anti-Hebbian rules, with broadened profiles for the animals with behaviorally verified tinnitus (Koehler SD, Shore SE. J Neurosci 33: 19647-19656, 2013a). In the present study we show that well-timed bimodal stimulation induces alterations in the rate-level functions (RLFs) of fusiform cells. The RLF gains and maximum amplitudes show Hebbian modifications in sham and no-tinnitus animals but anti-Hebbian modifications in noise-exposed animals with evidence for tinnitus. These findings suggest that stimulus-timing bimodal plasticity produced by the DCN circuitry is a contributing mechanism to enhanced central gain associated with tinnitus.

Keywords: dorsal cochlear nucleus; multisensory integration; neural plasticity; rate-level functions; tinnitus.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cochlear Nucleus / cytology
  • Cochlear Nucleus / physiology
  • Cochlear Nucleus / physiopathology
  • Evoked Potentials, Auditory*
  • Female
  • Guinea Pigs
  • Neuronal Plasticity*
  • Neurons / physiology
  • Noise
  • Tinnitus / physiopathology*