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KMID : 1144120150050020124
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Biomedical Engineering Letters
2015 Volume.5 No. 2 p.124 ~ p.130
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Effect of axon diameter and electrode position on responses to sinusoidally amplitude-modulated electric pulse-train stimuli
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Yang Hye-Jin
Woo Ji-Hwan
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Abstract
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Purpose: Cochlear implant systems restore the sense of sound by stimulating auditory nerve fibers (ANFs) with surgically implanted electrodes. Neural activity elicited by electrical pulse-trains conveys sound information to the brain. Thus, it is important to understand how ANFs produce the temporal sequence of neural activity in response to sinusoidally amplitude-modulated (SAM) pulse-trains with a rate of 5,000 pulses/s. In this study, we evaluated the effects of axon diameter (1.2 to 4.6 μm) and the electrode-to-axon distance (0.525 to 1.00 mm) on the response to 100 Hz SAM pulse-trains using a computational ANF model.
Methods: The model uses a Hodgkin-Huxley computation that incorporates the kinetics of sodium and potassium channels and an adaptation component. Simulated responses were analyzed by computing vector strength (VS) and the amplitude of the fast Fourier transform component at the modulation component (F0 amplitude).
Results: Axon diameter significantly influenced neural responses to SAM pulse-train stimuli. As the axon diameter increased, the VS and F0 amplitude increased. However, the VS and F0 amplitude were less influenced by the electrode-to-axon distance.
Conclusions: Finally, we concluded that larger-diameter ANFs could more precisely convey temporal information of speech sound.
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KEYWORD
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Neural modeling, Cochlear implant, Electrical stimulation, Auditory nerve
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