Description
Conduct ABR software |
Conduct ABR Maze software |
Maze Engineers Sound System |
Maze Engineers control box |
Speaker |
Real-time sound lever reader |
Electronic controller and sound generator |
Brain response recorder |
TDT Rz6 Multi-I/O high-frequency auditory processor |
Mouse Auditory Brainstem Response Test |
Isolation Cubicle |
Animal enclosure |
Maze Engineers control box |
TDT RZ6 Multi-I/O high-frequency auditory processor |
Speaker |
Real-time sound lever reader |
Electronic controller and sound generator |
Features

Introduction
ABR recordings involve placing electrodes near the subject’s scalp to capture evoked potentials. When sound stimuli are presented, the auditory brainstem pathways—including cochlear ganglion neurons and their associated fiber tracts and nuclei—generate electrical responses that provide insights into the health of these neural structures. The ABR waveform typically comprises five distinct components, labeled I to V, reflecting the activation of the auditory nerve and the processing of sound through the brainstem pathways.
Apparatus and Equipment
The Rodent Audible Brainstem Response (ABR) Test setup features a soundproof isolation chamber with an animal enclosure, equipped with LED and infrared lighting. An external device can be connected through a customizable device slot, and a camera mount is positioned at the top of the chamber for observation.
The Maze Engineers control box interfaces with the TDT RZ6 processor to deliver TTL signals that synchronize with each stimulus presentation.
Sound stimuli are produced by a generator with adjustable parameters, and are played through two speakers capable of emitting tones or white noise. A sound meter is used to monitor and ensure accurate sound levels.
The rodent’s auditory neural pathway generates electrical responses to these stimuli, which the TDT RZ6 then records in high fidelity, capturing neural activity, stimulus waveforms, and related behavioral events.
The Conduct ABR Maze software enables the creation of customized sound stimuli protocols, allowing adjustments to parameters such as frequency, dB level, phase, and duration.
Protocol
Follow appropriate laboratory protocols, surgical hygiene, and animal welfare practices before commencing. Clean and sterilize all surgical equipment and other apparatus.
The following protocol considers a mouse as the subject. The protocol can be applied to other small rodents as well.
Data Analysis
These data recored from the rodent auditory brainstem response apparatus can be used to evaluate hearing function, diagnose hearing disorders, study the effects of ototoxic drugs or noise exposure on the auditory system, assess the efficacy of hearing protection devices or therapies, and investigate the neural mechanisms of hearing and auditory processing.
- Hearing threshold: The minimum sound intensity required to elicit an ABR waveform. This is an objective measure of hearing sensitivity.
- Latency: The time interval between the onset of the acoustic stimulus and the occurrence of the corresponding ABR peak. This provides information about the speed of neural conduction along the auditory pathway.
- Amplitude: The magnitude of the ABR peak, which reflects the number of synchronized firing of auditory neurons. This can indicate the integrity of the auditory pathway.
- Waveform morphology: The shape of the ABR waveform, which can reveal information about the functional organization of the auditory system and the type of hearing loss.
- Interwave interval: The time interval between successive ABR peaks, which can provide insights into the timing and processing of auditory information.
- Signal-to-noise ratio: The difference between the amplitude of the ABR response and the background noise level, which reflects the quality of the ABR recording and the reliability of the measurement.
Literature Review
Recommendations, Considerations, and Precautions
- Prior to anesthetization of the subjects, calibrate, program, and check all devices and equipment for proper functioning.
- Use a Faraday cage inside the sound-proof chamber to prevent interference from external electronic devices.Â
- Use a non-electric heating pad during ABR testing to avoid any interferences during recordings.
- To prevent the possibility of the subject waking up during ABR recording sessions (approximately 40-minute sessions), inject one-fifth of the original dose of the anesthetic at about 20 minutes during testing.
- Provide appropriate post-experimental recovery and pain management to the subjects following ABR recordings.
References
- Akil, O., Oursler, A. E., Fan, K., & Lustig, L. R. (2016). Mouse Auditory Brainstem Response Testing. Bio-protocol, 6(6), e1768. https://doi.org/10.21769/BioProtoc.1768Â
- Akil, O., Sun, Y., Vijayakumar, S., Zhang, W., Ku, T., Lee, C. K., … & Lustig, L. R. (2015). Spiral ganglion degeneration and hearing loss as a consequence of satellite cell death in saposin B-deficient mice. Journal of Neuroscience, 35(7), 3263-3275.
- Galambos, R., & Hecox, K. E. (1978). Clinical applications of the auditory brain stem response. Otolaryngologic Clinics of North America, 11(3), 709-722.
- Sohmer, H., Freeman, S., Friedman, I., & Lidan, D. (1991). Auditory brainstem response (ABR) latency shifts in animal models of various types of conductive and sensori-neural hearing losses. Acta oto-laryngologica, 111(2), 206–211. https://doi.org/10.3109/0001648910913737
- Jewett, D. L., & Williston, J. S. (1971). Auditory-evoked far fields averaged from the scalp of humans. Brain, 94(4), 681-696.
- Lundt, A., Soos, J., Henseler, C., Arshaad, M. I., Müller, R., Ehninger, D., … & Weiergräber, M. (2019). Data acquisition and analysis in brainstem evoked response audiometry in mice. JoVE (Journal of Visualized Experiments), (147), e59200.
- O’Leary, T. P., Shin, S., Fertan, E., Dingle, R. N., Almuklass, A., Gunn, R. K., … & Brown, R. E. (2017). Reduced acoustic startle response and peripheral hearing loss in the 5xFAD mouse model of Alzheimer’s disease. Genes, Brain and Behavior, 16(5), 554-563.
- Liu, Y., Fang, S., Liu, L. M., Zhu, Y., Li, C. R., Chen, K., & Zhao, H. B. (2020). Hearing loss is an early biomarker in APP/PS1 Alzheimer’s disease mice. Neuroscience letters, 717, 134705.
- Huang, S., Xu, A., Sun, X., Shang, W., Zhou, B., Xie, Y., … & Han, F. (2020). Otoprotective Effects of α-lipoic Acid on A/J Mice with Age-related Hearing Loss. Otology & Neurotology, 41(6), e648-e654.