Comparison of neuronal network models for tinnitus management by sound therapy

Tinnitus is a condition in which sounds heard in the ear or head without any external sound. There are many therapeutic approaches for tinnitus and sound therapy is one of the techniques for its treatment that have been proposed. In order to investigate mechanisms of tinnitus generation and the clinical effects of sound therapy from the viewpoint of neural engineering, we have proposed computational models with plasticity and inhibitory feedback using a neural oscillator or model neurons described by simplified Hodgkin-Huxley equations. By hypothesizing that the oscillation and the non-oscillatory state in the models correspond to generation and inhibition of tinnitus, respectively, we found out that the models could explain the fact that the habituated human auditory system temporarily halts perception of tinnitus following sound therapy. However, a simpler model without inhibitory feedback can exhibit the solutions that exist in the former models. In the present paper, outcomes of the neuronal network model, which is incorporated with inhibitory feedback, are compared with the model without inhibitory feedback. It was revealed that the former is superior since it has a larger parameter region in which the effects of sound therapy can be restored due to synaptic plasticity.