BIO SCI N147 Lecture Notes - Lecture 23: Cochlear Implant, Digital Filter, Cochlear Nerve
7 Jan 2018
School
Department
Course
Professor
Document Summary
Implant in the scala tympani of the cochlea and stimulate the electrodes individually. Frequency analyzed by digital filter bank in speech processor. Cochlear mechanics transduced to receptor potential by cochlear inner hair cells. Auditory nerve activated by cochlear hair cells via chemical synapse. *cochlear implants don"t have access to fine temporal info. Ci electrodes and auditory-nerve fibers: currents from nearby electrodes tend to add, resulting in interference among electrodes, electrodes are sitting in parylim (like saline) electricity flows between electrodes. Implants have 16-22 electrodes, but patients receive only 6-9 independent channels of info. Interactions among channels reduce the number of independent channels of info: loss of hair cells loss of auditory nerve fibers, really only getting info from 8 channels even when. 16 channels are there: activation is not limited to single nerve fibers spread of activation depends on electrode configuration. Auditory: success with an implant requires intact auditory nerve fibers.
