Artikel
Electrophonic and electroneural hearing with combined electric/acoustic stimulation (EAS) of the cochlea
Elektrophones und elektroneurales Hören bei kombinierter elektrisch/akustischer Stimulation (EAS) der Cochlea
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Autoren
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Maike Vollmer
- University of California, San Francisco, San Francisco, USA
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Jochen Tillein
- J.W. Goethe University, Frankfurt/Main, Germany
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Ben H. Bonham
- University of California, San Francisco, San Francisco, USA
| Veröffentlicht: | 7. September 2006 |
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Gliederung
Text
In an animal model we studied the central neuronal encoding of combined electrical and acoustical stimulation (EAS) of the cochlea in the presence of intact hair cells.
Under general anesthesia normal hearing cats were implanted with a scala
tympani electrode array. For acoustic stimulation an earphone was sealed to the ipsilateral auditory meatus. Neuronal responses to pulsatile and sinusoidal stimuli were recorded simultaneously at 16 sites along the tonotopic gradient of the contralateral inferior colliculus (IC).
At low intensities, electric probe frequencies activate IC locations
that correspond to the probe frequency. These electrophonic responses have acoustic-like response patterns (shallow growth function and large dynamic range) and are masked when the electric signal is preceded by acoustic stimuli of the same frequency.
At higher electrical intensities, additional IC locations are activated that
correspond to the cochlear site of the stimulating electrode(s). These electroneural responses are based on the direct activation of the auditory nerve and typically demonstrate a steep growth function and a narrow dynamic range. Electroneural responses are masked by acoustic frequencies that correspond to the cochlear site of electrical stimulation.
The findings indicate that electrical stimulation of the hearing cochlea can produce two different kinds of auditory responses: low-threshold acoustic-like electrophonic responses and higher-threshold electroneural responses of the auditory nerve. The interactions between these two response patterns may influence the efficacy of combined stimulation in EAS patients.
(Supported by NOHR, NIH N01 DC-2-1006, NIH N01 DC-3-1006 and MedEl)
