An integrative model of tinnitus based on a central gain controlling neural sensitivity

The purpose of the current review is to propose a model highlighting the putative connections between hearing loss and the phantom perception of tinnitus (tinnitus being accompanied by hearing loss in the majority, if not all, subjects). Sensory deprivation is followed by dramatic functional and structural changes in the auditory system. Notably, while cochlear injuries are accompanied by a reduced activity in the cochlear nerve, neural activity is increased at virtually all levels in the central auditory system. We suggest that this central hyperactivity could result from a central gain increase; the general purpose of this gain modulation being to adapt neural sensitivity to the reduced sensory inputs, preserving a stable mean firing and neural coding efficiency. However, maintaining neural homeostasis at all costs, in the event of an auditory system sensory deprivation, could be done at the price of amplifying "neural noise" due to the overall increase of gain (or sensitivity), ultimately resulting in the generation of tinnitus. The clinical implications of this model are also presented.