Measuring the Auditory Brainstem Response in Mice

Abstract

Source: Lee, D., et. al. Modified Experimental Conditions for Noise-Induced Hearing Loss in Mice and Assessment of Hearing Function and Outer Hair Cell Damage. J. Vis. Exp. (2023)

This video demonstrates the measurement of auditory brainstem response (ABR) in a mouse. Electrodes are placed on the head, behind the ear, and near the tail of an anesthetized mouse. Acoustic stimuli at various intensities are delivered, and electric signals generated are recorded as waveforms.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Auditory brainstem response (ABR)-based assessment of hearing threshold

1. Use a commercial ABR testing system specifically designed for small animals.
2. Intraperitoneally inject a mixture of tiletamine and zolazepam (40 mg/kg) and xylazine (9.3 mg/kg) into the mice for general anesthesia.
   NOTE: ABR assessment takes ~2 h. Make sure to provide thermal support via a heating pad and apply eye ointment to prevent dryness while the mouse is under anesthesia.
3. Measure the ABR in the mouse under general anesthesia. Place subdermal needle electrodes (12 mm) at the vertex, behind the pinna of the left ear, and back near the tail to measure the hearing threshold.
4. Present acoustic stimuli using a speaker placed 1 cm from the animal's left ear.
5. Use an oscilloscope to control the acoustic stimuli. Choose Sine Wave for the stimuli and 10 k for the window scale. Turn the Frequency knob to obtain the desired frequency of the acoustic stimuli.
6. Adjust the stimulus intensity by turning the amplitude or AMLP knob on the function generator. Obtain the desired stimulus intensity by turning the AMLP knob to a suitable voltage, calculated from calibration.
7. Collect the ABR measurements under a series of stimulus intensities, from 10 dB Sound Pressure Levelor SPL to 100 dB SPL, with a 10 dB step size.
   NOTE: Measure the hearing threshold in a soundproof box. The minimum stimulus intensity level that could give rise to a discernable Wave V in the collected signal was assumed to be the ABR threshold (Figure 1). Post-ABR assessment, monitor the animal until it recovers from anesthesia (~1 h).

Results

Figure 1: ABR measurement of hearing. Representative ABR results at 12 kHz, collected on the 13th day (1 we...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1/4" CCP Free-field Standard Microphone Set	GRAS	428158	For noise exposure
Amplifier Input Module, AMI100D	BIOPAC		For auditory brainstem response
Bio-amplifier, BIO100C	BIOPAC		For auditory brainstem response
Evoked Response Amplifier, ERS100C	BIOPAC		For auditory brainstem response
High Performance Data Acquisition System, MP160	BIOPAC		For auditory brainstem response
Modular Extension Cable, MEC110C	BIOPAC		For auditory brainstem response
Needle Electrode, Unipolar 12 mmTp, EL452	BIOPAC		For auditory brainstem response
ROMPUN- xylazine injection, solution	Bayer HealthCare, LLC
Sound amplifier, MT-1000	unika		For noise exposure
Sound generator/analyzer/miscellaneous, FW-02	CLIO	620300719	For noise exposure
Soundproof chamber	IEA Electro-Acoustic Technology		For noise exposure and ABR
Speaker	IEA Electro-Acoustic Technology		For noise exposure
Stimulator Module, STM100C	BIOPAC		For auditory brainstem response
Tubephone Set, OUT101	BIOPAC		For auditory brainstem response
Zoletil	Virbac