Recovery characteristics of the electrically stimulated auditory nerve in deafened guinea pigs : Relation to neuronal status
| Autor: | Dyan Ramekers, Huib Versnel, Stefan Strahl, Wilko Grolman, Sjaak F.L. Klis |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
medicine.medical_specialty
Time Factors Refractory Period Electrophysiological Refractory period medicine.medical_treatment Hearing Loss Sensorineural Population Guinea Pigs Sensory system Audiology Research Support Hearing Furosemide Kanamycin Cochlear implant medicine Reaction Time otorhinolaryngologic diseases Journal Article Animals education Non-U.S. Gov't Cochlear Nerve Spiral ganglion education.field_of_study Pulse (signal processing) business.industry Research Support Non-U.S. Gov't Recovery of Function medicine.disease Cochlear Implantation Electric Stimulation Sensory Systems Disease Models Animal medicine.anatomical_structure Nerve Degeneration Auditory Perception Evoked Potentials Auditory Sensorineural hearing loss Female Hair cell business Spiral Ganglion Perceptual Masking |
| Zdroj: | Hearing Research, 321, 12. Elsevier |
| ISSN: | 0378-5955 |
| Popis: | Successful cochlear implant performance requires adequate responsiveness of the auditory nerve to prolonged pulsatile electrical stimulation. Degeneration of the auditory nerve as a result of severe hair cell loss could considerably compromise this ability. The main objective of this study was to characterize the recovery of the electrically stimulated auditory nerve, as well as to evaluate possible changes caused by deafness-induced degeneration. To this end we studied temporal responsiveness of the auditory nerve in a guinea pig model of sensorineural hearing loss. Using masker-probe and pulse train paradigms we compared electrically evoked compound action potentials (eCAPs) in normal-hearing animals with those in animals with moderate (two weeks after ototoxic treatment) and severe (six weeks after ototoxic treatment) loss of spiral ganglion cells (SGCs). Masker-probe interval and pulse train inter-pulse interval was varied from 0.3 to 16 ms. Whereas recovery assessed with masker-probe was roughly similar for normal-hearing and both groups of deafened animals, it was considerably faster for six weeks deaf animals (τ ≈ 1.2 ms) than for two weeks deaf or normal-hearing animals (τ ≈ 3–4 ms) when 100-ms pulse trains were applied. Latency increased with decreasing inter-pulse intervals, and this was more pronounced with pulse trains than with masker-probe stimulation. With high frequency pulse train stimulation eCAP amplitudes were modulated for deafened animals, meaning that amplitudes for odd pulse numbers were larger than for even pulses. The relative refractory period (τ) and the modulation depth of the eCAP amplitude for pulse trains, as well as the latency increase for both paradigms significantly correlated with quantified measures of auditory nerve degeneration (size and packing density of SGCs). In addition to these findings, separate masker-probe recovery functions for the eCAP N 1 and N 2 peaks displayed a robust non-monotonic or shoulder-shaped course in all animals. The time interval between the N 1 and N 2 correlated with neuronal refractoriness, suggesting that the N 2 peak reflects a second firing of part of the SGC population. We conclude that – compared to the commonly used masker-probe recovery functions – recovery functions obtained with pulse train stimulation may provide a means to augment differences and, by doing so, to more potently discriminate between auditory nerve conditions. |
| Databáze: | OpenAIRE |
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