Acoustic Trauma Exposure
Objective: To induce tinnitus in chinchillas through acoustic trauma exposure and assess behavioral and neurophysiological changes
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Protocol Steps
Psychophysical training and baseline testing
Chinchillas were psychophysically trained and tested before acoustic trauma exposure to establish baseline auditory discrimination performance
Note: Two groups were matched in terms of auditory discrimination performance for noise and 1, 4, 6, and 10 kHz tones
View evidence from paper
“Chinchillas were psychophysically trained and tested before and after exposure to a traumatic unilateral 80 dB (sound pressure level) 4 kHz tone. Before exposure, two groups were matched in terms of auditory discrimination performance (noise, and 1, 4, 6, and 10 kHz tones)”
Acoustic trauma exposure
Exposed group received unilateral acoustic trauma at 80 dB sound pressure level at 4 kHz frequency
Note: Exposure was unilateral (one ear only)
View evidence from paper
“exposure to a traumatic unilateral 80 dB (sound pressure level) 4 kHz tone”
Post-exposure psychophysical testing
After acoustic trauma exposure, chinchillas were tested for auditory discrimination performance using the same stimuli as baseline testing
Note: Testing included discrimination of noise and 1, 4, 6, and 10 kHz tones
View evidence from paper
“After exposure, a single psychophysical difference emerged between groups. The exposed group displayed enhanced discrimination of 1 kHz tones”
Single-unit electrophysiological recordings
Single-unit recordings were obtained from dorsal cochlear nucleus fusiform cells from both exposed and unexposed animals
Note: Recordings were obtained from putative fusiform cells of the DCN. Increased activity was more pronounced on the exposed side
View evidence from paper
“After psychophysical testing, single-unit recordings were obtained from each animal's DCN fusiform cell layer. Putative fusiform cells of exposed animals showed significantly ( p = 0.0136) elevated spontaneous activity”
Stimulus-evoked response testing
During single-unit recordings, responses to various tone frequencies and noise were measured
Note: Stimuli included tones at 1 kHz, characteristic frequency, other frequencies, and noise
View evidence from paper
“Putative fusiform cells of exposed animals showed a greater stimulus-evoked response to tones at 1 kHz ( p = 0.0000006) and at characteristic-frequency ( p = 0.0000009)”