Electrically Evoked Whole Nerve Action Potentials in Ineraid Cochlear Implant Users: Responses to Different Stimulating Electrode Configurations and Comparison to Psychophysical Responses Electrically evoked whole nerve action potentials (EAP) have been recorded from 20 Ineraid cochlear implant users in response to bipolar and/or monopolar electrical stimulation of the cochlea. EAP growth functions and refractory recovery functions were obtained for a variety of different stimulating conditions. Where possible, parallel psychophysical experiments were conducted ... Research Article
Research Article  |   June 01, 1996
Electrically Evoked Whole Nerve Action Potentials in Ineraid Cochlear Implant Users: Responses to Different Stimulating Electrode Configurations and Comparison to Psychophysical Responses
 
Author Affiliations & Notes
  • Carolyn J. Brown
    Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City
  • Paul J. Abbas
    Department of Otolaryngology Head and Neck Surgery and Department of Speech Pathology and Audiology, University of Iowa, Iowa City
  • James Borland
    Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City
  • Michael R. Bertschy
    Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City
  • Contact author: Carolyn J. Brown, PhD, Department of Otolaryngology, Head and Neck Surgery, University of Iowa, 200 Hawkins Drive #E230 GH, Iowa City, IA 52242.
    Contact author: Carolyn J. Brown, PhD, Department of Otolaryngology, Head and Neck Surgery, University of Iowa, 200 Hawkins Drive #E230 GH, Iowa City, IA 52242.×
Article Information
Hearing & Speech Perception / Hearing Aids, Cochlear Implants & Assistive Technology / Hearing / Research Articles
Research Article   |   June 01, 1996
Electrically Evoked Whole Nerve Action Potentials in Ineraid Cochlear Implant Users: Responses to Different Stimulating Electrode Configurations and Comparison to Psychophysical Responses
Journal of Speech, Language, and Hearing Research, June 1996, Vol. 39, 453-467. doi:10.1044/jshr.3903.453
History: Received May 22, 1995 , Accepted January 5, 1996
 
Journal of Speech, Language, and Hearing Research, June 1996, Vol. 39, 453-467. doi:10.1044/jshr.3903.453
History: Received May 22, 1995; Accepted January 5, 1996

Electrically evoked whole nerve action potentials (EAP) have been recorded from 20 Ineraid cochlear implant users in response to bipolar and/or monopolar electrical stimulation of the cochlea. EAP growth functions and refractory recovery functions were obtained for a variety of different stimulating conditions. Where possible, parallel psychophysical experiments were conducted that measured the just detectable increment in stimulus current level (JND), forward-masking functions, and detection thresholds for a range of different stimuli. Variations in EAP threshold, slope of the EAP growth function, and the rate of recovery of the EAP from the refractory state were observed both across subjects for a given place and by mode of stimulation (bipolar versus monopolar), as well as across electrodes within a subject. A poor correlation between slope of the EAP growth functions and current JNDs was obtained. However, good correlations were observed between EAP threshold and psychophysical detection threshold and between the EAP refractory recovery functions and the psychophysical forward-masking functions. Our interpretation of these findings is that these particular physiological measures are related to the excitability of the auditory nerve to electrical stimulation and further that these measures are related to performance of cochlear implant patients on listening tasks. Consequently, such information may prove to be useful in adjusting the stimulation parameters of the cochlear implant speech processor in order to maximize an individual’s performance with the device.

Acknowledgments
This research was supported, in part, by research grant DC00242 from the National Institutes of Health/NIDCD; grant RR59 from the General Clinical Research Centers Program, Division of Research Resources, NIH; and the Iowa Lions Sight and Hearing Foundation. The authors wish to thank George Woodworth for performing the statistical analyses.
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