Modelling the response of auditory midbrain neurons in the grassfrog to temporally structured monaural stimuli.

In a previous paper [Van Stokkum and Gielen, Hear. Res. 41, 71-86, 1989] a model was presented to describe the processing of monaural stimuli by the auditory periphery of the grassfrog. The main components of this model were: a middle ear filter, transduction and tuning of the haircell, short-term adaptation, action potential (event) generation with refractory properties, and spatiotemporal integration of converging inputs. The model is now extended to model auditory midbrain neurons as third order neurons. The mechanisms that generate selectivity for temporal characteristics of sound are adaptation, coincidence detection of second order neurons, temporal integration of third order neurons, and most important, event generation of the first, second and third order model neurons. Variation of the parameters of the model successfully reproduces the range of response patterns which have been obtained from eighth nerve fibres, dorsal medullary nucleus neurons, and torus semicircularis neurons without inhibition. With a single set of parameters the output of the model in response to a set of spectrally and temporally structured stimuli qualitatively resembles the responses of a single neuron to all these stimuli. In this way the responses to the different stimuli are synthesized into a framework, which functionally describes the neuron.