Effects of rates of spontaneous synaptic vesicle secretions in inner hair cells on information transmission in an auditory nerve fiber model.

In this article, we investigate how the rates of spontaneous synaptic vesicle secretions affect information transmission of the spike trains in response to the inner hair cell (IHC) synaptic currents in an auditory nerve fiber (ANF) model through computer simulations. The IHC synaptic currents were modeled by a filtered inhomogeneous Poisson process modulated with sinusoidal functions, while the stochastic ion channel model was incorporated into each node of Ranvier in the ANF model with spiral ganglion. The information rates were estimated from the entropies of the inter-spike intervals of the spike trains to evaluate information transmission in the ANF model. The results show that the information rates increased, reached a maximum, and then decreased as the rate of spontaneous secretion increased, implying a resonance phenomenon dependent on the rate of spontaneous IHC synaptic secretions. In conclusion, this phenomenon similar to the regular stochastic resonance may be observed due to that spontaneous IHC synaptic secretions may act as an origin of fluctuation or noise, and these findings may play a key role in the design of better auditory prostheses.