$890.00 – $24,850.00
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 |
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.
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.
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.
The subjects included postnatal 7 days old A/J mouse pups that were randomly divided into untreated groups, the DMSO (dimethyl sulfoxide) group, and α-lipoic acid + DMSO group (a-lipoic acid-treated group). The α -lipoic acid group received a dose of 50 mg/g of body intraperitoneal injections of α-lipoic acid dissolved in DMSO (50 mg/ml) on alternate days, while the control group received an equal amount of vehicle only. ABR testing for all groups was performed at ages 3-, 4-, 6-, and 8-weeks using stimuli of click and pure-tone bursts (8 kHz, 16 kHz, and 32 kHz) by reducing the SPL at 10 dB steps, then at 5 dB steps up and down to the lowest level wherein the ABR pattern could be recognized. The α-lipoic acid group displayed significantly reduced ABR thresholds for both stimuli and all tested frequencies in comparison to the untreated group at ages 4-, 6-, and 8-weeks. Additionally, the α-lipoic acid-treated group also had significantly lower ABR thresholds at 32 kHz frequency at 3-weeks old. In comparison to the control group, overall, the α-lipoic acid-treated group had lower ABR thresholds. (Huang et al., 2020)
The possibility of hearing loss as an early biomarker of Alzheimer’s disease was evaluated using APP/PS1 AD mice with wild-type littermates as controls. In addition to ABR testing, mice also underwent distortion product otoacoustic emission (DPOAE) and cochlear microphonics (CM) recordings. ABR recordings were performed monthly starting at postnatal day 60 to evaluate progressive changes and early occurrence of hearing loss. The testing was performed with clicks and a series of tone bursts with frequencies between 4 to 40 kHz, sound pressure intervals (SPI) in steps of 5 dB from 10 to 80 dB using a high-frequency speaker. For mice with severe hearing loss, sound pressure intervals range of 70 to 100 dB were used. A significant increase (10−20 dB SPL) in the ABR thresholds was observed in APP/PS1 AD mice in comparison to the wild-types. At 40 kHz, the ABR thresholds increased by approximately 20 dB SPL in APP/PS1 AD mice. Hearing loss was also observed to be progressive and age-based. Comparison between the two groups revealed APP/PS1 mice to display hearing loss as early as two months old at high frequency. These mice also had reduced DPOAE, though no reduction in CM could be observed. (Liu et al., 2020)
Prior to being submitted to ABR testing, Male and female 5xFAD mice and their wild-type counterparts were evaluated for their acoustic startle and pre-pulse inhibition (see Acoustic Startle Chamber). An age-related decline in acoustic startle responses was observed for 5xFAD mice. Following the acoustic startle testing, mice were subjected to ABR testing in age-grouped cohorts of mixed sexes; a 3-4 months group and a 13-14 months group. Testing was performed using tone bursts stimuli of 2, 4, 8, 16, and 32 kHz, 10 ms duration, and 1 ms rise/fall time using a loudspeaker. Tones were presented with an SPL of 5 dB, in descending sequence from 90 dB for each frequency. Thresholds were determined based on the repeatable III wave in ABR at the lowest sound level. Each ABR testing session lasted about 45 minutes. While no genotype differences could be observed for 3-4 months old mice, a significant effect of stimulus frequency could be seen. The 5xFAD mice displayed higher thresholds than the WT at 13 to 14 months of age, with an average ABR threshold of 82.2+/-4.8 dB in comparison to the 55.4+/-6.5 dB for WT mice. Additionally, it was observed that at frequencies of 8, 16, and 32 kHz, the auditory thresholds of the 5xFAD mice were significantly higher than the WT group. While an increase in auditory threshold with age for WT was only observed at 2 and 4 kHz, the mouse model displayed an increase for all frequencies. Together with the results of cochlear morphology, it was confirmed that the aged 5xFAD mice presented significant peripheral hearing loss. (O’Leary et al., 2017)
The study was conducted using C57BL/6J Sap B KO (B-/-) mice backcrossed to an FVB (Friend leukemia virus, strain B) strain to the 10th generation. The B-/- mice, Heterozygote (Het), and wild-type (WT) littermates (P1mo–P15mo) were subjected to Auditory Brainstem Response testing to determine the effect of Sap B deficiency on hearing in this progressive neuronal degeneration model. Mice were tested using clicks (5 ms duration, 31 Hz) and tone pips at 8, 16, and 32 kHz (10 ms duration, cos2 shaping, 21 Hz) at ages P1mo, P3mo, P4mo, P6mo, P8mo, P13mo, and P15mo. Electroencephalographic (EEG) activity was recorded for each stimulus for 20 ms (at a sampling rate of 25 kHz) and filtered (0.3–3 kHz). 512 stimuli and 1000 stimuli were averaged from the waveforms for click stimuli and frequency-specific tone pips, respectively. The Auditory Brainstem Responses were recorded down from the maximum amplitude in SPL of 5 dB. No significant differences in ABR thresholds were observed between the three cohorts at age P4mo; however, an increase in ABR thresholds for tone-burst stimuli only was observed in B-/- mice in comparison to the other two groups at P8mo. Further, no significant difference in thresholds could be observed for WT versus B-/- mice in click stimuli until P13mo, though significant threshold shifts for pure-tone stimuli were observed starting at P6mo. While no significant difference in ABR wave I amplitude for click stimulus could be seen at Pmo4, however, by P8mo, B-/- mice had a significant decrease in ABR amplitude in comparison to WT counterparts. Comparison of ABR interpeak latency between P1 and P2 at varying time points revealed that B-/- mice displayed significant P2-P1 delays for tone stimuli at P8mo. (Akil et al., 2015)
| Rodent Auditory Brainstem Response Test | Brain response recorder, Conduct ABR software, Maze Engineers Sound System, Mouse Auditory Brainstem Response Test |
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