Psychophysical Discrimination Testing
Objective: To assess auditory discrimination abilities in chinchillas before and after acoustic trauma exposure, and to correlate psychophysical performance changes with electrophysiological recordings from dorsal cochlear nucleus fusiform cells
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Protocol Steps
Baseline psychophysical testing
Chinchillas were psychophysically trained and tested on auditory discrimination tasks before acoustic trauma exposure
Note: Two groups were matched in terms of auditory discrimination performance at baseline
View evidence from paper
“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 stimulus
Note: Trauma consisted of 80 dB SPL 4 kHz tone applied unilaterally
View evidence from paper
“exposure to a traumatic unilateral 80 dB (sound pressure level) 4 kHz tone”
Post-exposure psychophysical testing
Chinchillas were tested on auditory discrimination of noise and tones (1, 4, 6, and 10 kHz) after acoustic trauma exposure
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 in both exposed and unexposed animals
Note: Recordings were made from putative fusiform cells of the DCN fusiform cell layer
View evidence from paper
“After psychophysical testing, single-unit recordings were obtained from each animal's DCN fusiform cell layer”
Analysis of spontaneous activity
Spontaneous activity of putative fusiform cells was compared between exposed and unexposed animals
Note: Exposed animals showed significantly elevated spontaneous activity
View evidence from paper
“Putative fusiform cells of exposed animals showed significantly (p = 0.0136) elevated spontaneous activity, compared with cells of unexposed animals”
Analysis of stimulus-evoked responses
Stimulus-evoked responses to various frequencies and noise were recorded and compared between groups
Note: Greater responses observed at 1 kHz and characteristic frequency in exposed animals
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)”