A stochastic model of the electrically stimulated auditory nerve: Pulse-train response

The single-pulse model of the companion paper [1] is extended to describe r esponses to pulse trains by introducing a phenomenological refractory mecha nism, Comparisons with physiological data from cat auditory nerve fibers ar e made for pulse rates between 100 and 800 pulses/s, First, it is shown tha t both the shape and slope of mean discharge rate curves are better predict ed by the stochastic model than by the deterministic model, Second, while i nterpulse effects such as refractory effects do indeed increase the dynamic range at higher pulse rates, both the physiological data and the model ind icate that much of the dynamic range for pulse-train stimuli is due to stoc hastic activity. Third, it is shown that the stochastic model is able to pr edict the general magnitude and behavior of variance in discharge rate as a function of pulse rate; while the deterministic model predicts no variance at all.