What do cochlear implants teach us about the encoding of frequency in the auditory system?
This article explores the coding of frequency information in the auditory system from the viewpoint of what has been learnt from cochlear implants. Cochlear implants may provide a window on central auditory nervous system function by creating the possibility to separate place and temporal information. An existing model of frequency discrimination in the acoustically stimulated auditory system is extended to include electrical stimulation. To be able to predict frequency difference limens for acoustic stimulation, an important assumption is that one spike per stimulus cycle is available, which may be provided by the existence of a volley principle. It is shown that to predict frequency difference limens for electrical stimulation of the auditory system, it must also be assumed that electrical stimulation causes desynchronization at a central auditory nervous system integration centre. With these assumptions, the model predicts the degradation in frequency discrimination that occurs for electrical stimulation. Finally, it is shown that cochlear implants have not yet proven conclusively that either rate-place coding or temporal coding is predominant in the auditory system.
Hanekom
J J
JJ
Department of Electrical, Electronic and Computer Engineering, University of Pretoria.
D001306:Auditory Pathways / Q000502:physiology*; D019929:Cochlear Implantation; D003638:Deafness / Q000601:surgery*; D006801:Humans; D008954:Models, Biological; D013998:Time Perception / Q000502:physiology*