Pseudospontaneous activity: stochastic independence of auditory nerve fibers with electrical stimulation

We describe a novel signal processing strategy for cochlear implants design ed to emphasize stochastic independence across the excited neural populatio n. The strategy is based on the observation that high rate pulse trains may produce random spike patterns in auditory nerve fibers that are statistica lly similar to those produced by spontaneous activity in the normal cochlea , We call this activity 'pseudospontaneous'. A supercomputer-based computat ional model of a population of auditory nerve fibers suggests that differen t average rates of pseudospontaneous activity can be created by varying the stimulus current of a fixed-amplitude, high-rate pulse train, e.g. 5000 pp s. Electrically-evoked compound action potentials recorded in a human cochl ear implant subject are consistent with the hypothesis that such a stimulus can desynchronize the fiber population. This desynchronization may enhance neural representation of temporal detail and dynamic range with a cochlear implant and eliminate a major difference between acoustic and electric hea ring. (C) 1999 Published by Elsevier Science B.V. All rights reserved.