| 1996, 222, Session H1, Poster |
| A model of cochlear two-tone suppression using the saturating transfer characteristics of hair cells: Strengths and weaknesses |
| *Y. Cai, C.D. Geisler (University of Wisconsin-Madison, Madison) |
| A phenomenological model, using generally accepted theory, was developed to simulate two-tone suppression caused by "low-side" suppressors. The model uses the S-shaped transfer characteristic of the outer hair cell (OHC) to control the gain of the cochlear amplifier, which affects only frequencies near the characteristic frequency (CF).
Among other things, the model can simulate the 1/4 to 1/2 cycle differences between the phase of suppression and the phase of excitation to the suppressor-tone alone, which we have observed experimentally in auditory-nerve (AN) fiber discharges.
The model is also able to simulate the low-frequency biasing data and the suppression of the low-frequency component by the CF tone observed experimentally in OHC receptor potentials (Cheatham and Dallos, 1994, Hear. Res.).
These successful simulations provide support for the basic assumption of the model: that is, the saturation of the OHC transduction current produces two-tone suppression. However, using only the inner hair cell (IHC) stage, with its own S-shaped transfer curve the model also produces two-tone suppressions, which are characterized by half-cycle relationships between the phase of suppression and the phase of excitation to the suppressor-tone alone.
These results suggest that the basic temporal patterns of the two-tone suppression of AN fibers can be accounted for by saturation of OHC and/or IHC currents.
However, the amplitude behavior of the model fits only suppression data from auditory-nerve fibers with high spontaneous rates, but not from those with lower rates (cf. Cai and Geisler, 1995 ARO abstract). Thus, it appears that some other, presently unknown, mechanism(s) which operate at stage(s) after the formation of the IHC potentials are also involved in AN-fiber two-tone suppression, determining the magnitudes of the suppression. |
Citation for this abstract:
Cai, Y. and C.D. Geisler (1996). A temporal model of auditory two-tone suppression: Strength and Weakness. Assoc. Res. Otolaryngol. Abstr., p.?.
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