Modeling spectral processing in the central auditory system

Several models of the central nervous system (CNS) which further process the spatio-temporal firing pattern of the auditory nerve are presented. All these models suppose that for the CNS, the auditory nerve fibers are organized as individual groups whose central frequencies vary continuously, each individual group being composed of localized neighboring fibers, and that what the CNS does is to measure the coherence and cooperation of activities of fibers in each individual group, i.e. local coherence. The local coherence is in turn defined as the sum of each individual coherence which is a measure of coherence between the activities of two neighboring fibers. An internal representation of a stimulus, given at the output of the model, is thus composed of a series of measures of local coherence and cooperation. Two derivatives of this general conceptual model are described in detail, i.e. when the individual coherence is based on either cross correlation analysis or covariance