Stimulus-timing-dependent modifications of rate-level functions in animals with and without tinnitus.
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.
Kresge Research Institute, Department of Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan;
Roxana A
RA
Stefanescu
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland.
Seth D
SD
Koehler
Kresge Research Institute, Department of Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan; Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; and sushore@umich.edu.
Susan E
SE
Shore
D000818:Animals; D017626:Cochlear Nucleus / Q000166:cytology / Q000502:physiology / Q000503:physiopathology; D005072:Evoked Potentials, Auditory; D005260:Female; D006168:Guinea Pigs; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology; D009622:Noise; D014012:Tinnitus / Q000503:physiopathology*
dorsal cochlear nucleus; multisensory integration; neural plasticity; rate-level functions; tinnitus