simulating the human compound action potential elicited by

DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS

Simulating the Human Compound Action Potential

Elicited by Clicks, Chirps, and Amplitude Modulated Carriers

Yousef Alamri,Skyler Jennings,

University of Utah


Electrocochleography and cochlear potentials• Electrocochleography can be decomposed into:1) Cochlear microphonic (CM)

Outer hair cell contribution 2) Summating potential (SP)

Outer/inner hair cell contribution 3) Compound action potential (CAP)

Auditory nerve fiber contribution

+-

Adapted from Auditory Evoked Potentials, Burkard et al. (2006).


MODELING METHODS


Compound Action Potential (CAP)Uncoiled Cochlea*

Defines the appearance of the action potential at the site of the recording electrode

Action Potential

Input

Unitary Response

Output

*Google Images: thepsychologist.org (place theory)

PSTH

CAP Convolution model of Goldstein & Kiang,1958

50

150


Unitary responseElberling (1976)

Simulating PSTHsZilany et al. (2014) model

CAP

Model settings:221 CFs from 0.25 – 20 kHz.

Model with human cochlear tuning (Shera et al., 2002)

Normal OHC/IHC function

High-, medium-, and low-spontaneous rate fibers according to Liberman (1978).

Approach for simulating human CAPs

CAP Scaling was based on Antoli-Candela and Kiang (1978), and the observation that CAPs recorded from the round window of cats are 250 time those measured from the eardrum of humans.

Stimuli were identical to the human experiments

∗


RESULTS


Human Model

The model predicts the morphology of CAPs elicited by clicks

110 dB peSPL

80 dB

50 dB

60 dB

70 dB

90 dB

40 dB

100 dB

Acoustic stimulus *Data from Simpson et al. (2020)


- CAP amplitude increases as click level increases

- CAP latency decreases as the click level increases

The model predicts the amplitudes and latencies of CAPs elicited by clicks

ModelHuman

*Data from Simpson et al. (2020)


All fibersOnly high-spontaneous rate fibers

In the spirit of synaptopathy! Supra-threshold

reduction in CAP amplitude


Click- vs. Chirp-evoked CAPs

Click Chirp

Chirps are predicted to result in higher CAP amplitudes than clicks

Chirp latencies increase at a slower rate with decreasing intensity compare to clicks*Data from Chertoff et al. (2010)


Click- vs. Chirp-evoked CAPs70 dB peSPL Click

Chirps are predicted to evoke greater CAP amplitudes and generate greater across-CF synchrony in simulated PSTHs

70 dB peSPL Chirp

Upward spread of excitation is predicted to adapt high-CF fibers resulting in a reduction in CAP amplitude at high chirp levels.

110 dB peSPL Chirp


The model predicts the morphology of CAPs elicited by AM *

Human Model

Example stimulus: 80 Hz

Carrier parameters:• 80 dB SPL• 3000 Hz

Modulation rates:• 40-1000 Hz

* unpublished dataBy Jessica Chen


The model predicts the spectral components of CAPs elicited by AM

Human Model


Contributions of individual CFs to the predicted CAP evoked by AM

Phase locking to the modulation frequency observed primarily for CFs higher than the carrier frequency (3000 Hz)

80 Hz

Carrier parameters:• 80 dB SPL• 3000 Hz

Modulation rates:• 80 Hz

DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS• The model simulations support the following ideas:The human CAP…– emerges from synchronous auditory nerve activity– depends primarily on neural activity from the cochlear base when evoked

by a click– includes basal and apical contributions when evoked by a chirp– has non-linear morphology that originates from cochlear/auditory nerve

nonlinearity, not from level-dependent changes to the unitary response– is primarily the results of high-spontaneous rate fibers– has reduced supra-threshold amplitudes when low- and medium-

spontaneous rate fibers are absent, consistent with synaptopathy– exhibits robust phase locking to AM across a wide range of modulation

frequencies

• Future work:– Predicting derived-band CAP from high-pass masking experiments (e.g.,

Eggermont, 1976)– Simulate the effects of eliciting the medial olivocochlear reflex on CAPs

measured in quiet and background noise.– Design a novel chirp stimulus based on optimal model-predicted

synchrony.

Thank you.

Human Model


References• Antoli-Candela, F., & Kiang, N. Y. (1978). Unit activity underlying the N1 potential. In Evoked electrical activity

in the auditory nervous system (pp. 165-191). Academic Press New York.• Burkard, R. F., Eggermont, J. J., & Don, M. (2006). Auditory Evoked Potentials: Basic Principles and Clinical

Application (Point (Lippincott Williams & Wilkins)) (1st ed.). Lippincott Williams & Wilkins.• Chertoff, M., Lichtenhan, J., & Willis, M. (2010). Click-and chirp-evoked human compound action potentials.

The Journal of the Acoustical Society of America, 127(5), 2992-2996.• Eggermont, J. J. (1976). Analysis of compound action potential responses to tone bursts in the human and

guinea pig cochlea. The Journal of the Acoustical Society of America, 60(5), 1132-1139.• Elberling, C.: Simulation of cochlear action potentials recorded from the ear canal in man. In: Ruben, R.J.,

Salomon, G., Elberling, C. (Eds.): Proc. symposium on electrocochleography. 1974• Goldstein, M.H., & Kiang, N. (1958). Synchrony of Neural Activity in Electric Responses Evoked by Transient

Acoustic Stimuli. Journal of the Acoustical Society of America, 30, 107-114.• Liberman, M. C. (1978). Auditory-nerve response from cats raised in a low-noise chamber. The Journal of the

Acoustical Society of America, 63(2), 442-455.• Naunton, R., & Fernández, C. (1978). Evoked electrical activity in the auditory nervous system.• Shera, C. A., Guinan, J. J., & Oxenham, A. J. (2002). Revised estimates of human cochlear tuning from

otoacoustic and behavioral measurements. Proceedings of the National Academy of Sciences, 99(5), 3318-3323.

• Simpson, M. J., Jennings, S. G., & Margolis, R. H. (2020). Techniques for Obtaining High-quality Recordings in Electrocochleography. Frontiers in systems neuroscience, 14.

• Zilany, M.S., Bruce, I., & Carney, L. (2014). Updated parameters and expanded simulation options for a model of the auditory periphery. The Journal of the Acoustical Society of America, 135 1, 283-6 .

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