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Updated: May 21, 2026

Optogenetic Stimulation of the Auditory Nerve
Published on: October 8, 2014
Monopolar intracochlear pulse trains selectively activate the inferior colliculus
Matthew C Schoenecker1, Ben H Bonham, Olga A Stakhovskaya
1Department of Bioengineering, University of California San Francisco, San Francisco, CA 94143-0526, USA. mcschoenecker@gmail.com
Cochlear implants with monopolar stimulation show selective neuronal activation, comparable to bipolar or acoustic stimuli. This challenges previous assumptions about broad activation patterns, offering new insights for auditory system research.
Area of Science:
- Neuroscience
- Auditory System Research
- Cochlear Implant Technology
Background:
- Previous studies suggested monopolar cochlear implant stimulation causes broad neuronal activation.
- However, psychophysical studies with sustained pulse trains showed no clear performance differences between monopolar and bipolar configurations.
Purpose of the Study:
- To investigate if monopolar intracochlear stimulation can achieve selective inferior colliculus activation.
- To compare activation widths of monopolar, bipolar, and acoustic stimuli along the tonotopic axis.
Main Methods:
- Measured neuronal activation widths in guinea pigs and cats using acoustic tones and electrical pulse trains (1,000 pulses/s).
- Utilized a 6-12 electrode array in the scala tympani for electrical stimulation.
- Compared transient and sustained response activation widths.
Main Results:
- Sustained responses showed narrower activation widths than transient responses for all stimulus types (monopolar, bipolar, acoustic).
- Monopolar and bipolar stimuli yielded similar activation widths at comparable peak spike rates.
- In guinea pigs, monopolar and bipolar stimuli produced narrower sustained activation than acoustic tones at similar peak rates.
Conclusions:
- Intracochlear electrical stimulation with monopolar pulse trains can achieve selective neuronal activation.
- Monopolar stimulation's selectivity is comparable to bipolar or acoustic stimulation.
- Findings challenge previous notions of broad activation with monopolar configurations.
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