Cortical tonotopic map reorganization and its implications for treatment of tinnitus.
CONCLUSIONS
There appears to be a definite link between reorganization of the cortical tonotopic map and increased spontaneous firing rates. The results have implications for the reduction of noise-induced hearing loss and in the prevention of noise-induced tinnitus in humans.


OBJECTIVE
To review animal and human studies related to neural correlates of tinnitus. Among those are increased spontaneous firing rate, enhanced neural synchrony, and reorganization of the cortical frequency-place (tonotopic) map.


METHODS
To separate these issues one would want to have a situation where hearing loss is present but without reorganization of the cortical frequency-place map. For that purpose, noise-exposed cats were placed, immediately after the trauma and for at least 3 weeks, either in a quiet or in a high-frequency or low-frequency enriched acoustic environment.


RESULTS
In exposed cats that were placed in the quiet environment there was an increase in spontaneous firing rate and synchrony of neurons in primary auditory cortex. In contrast, exposed cats placed in the high-frequency-enriched acoustic environment did not show any significant difference in spontaneous firing rate or synchrony compared to the non-traumatized controls.
Eggermont
J J
JJ
Department of Physiology, University of Calgary, Calgary, Alberta, Canada. eggermon@ucalgary.ca
D000818:Animals; D001303:Auditory Cortex / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods*; D002415:Cats; D003056:Cochlear Nerve / Q000503:physiopathology; D004569:Electroencephalography; D004777:Environment; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods; D014012:Tinnitus / Q000503:physiopathology* / Q000628:therapy*