simulating the human compound action potential elicited by
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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
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
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).
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MODELING METHODS
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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
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
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
∗
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RESULTS
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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)
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
- 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)
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All fibersOnly high-spontaneous rate fibers
In the spirit of synaptopathy! Supra-threshold
reduction in CAP amplitude
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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)
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
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
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
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
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
The model predicts the spectral components of CAPs elicited by AM
Human Model
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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
DEPARTMENT OF COMMUNICATION SCIENCES AND DISORDERS
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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