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Growth of evoked potential amplitude in neonatal chicks exposed to intense sound
F A Pugliano1, E Pribitikin, H J Adler
1Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania, Philadelphia.
Insights
Neonatal chicks exposed to loud noise showed significant auditory recovery within 3 days, but abnormal amplitude growth persisted for 10 days, indicating complex hearing damage and repair processes.
Area of Science:
- Auditory Neuroscience
- Animal Models of Hearing Loss
- Ototoxicity Research
Background:
- Intense sound exposure can cause temporary or permanent hearing loss.
- Understanding the mechanisms of auditory recovery is crucial for developing treatments.
- Neonatal chicks provide a valuable model for studying auditory development and damage.
Purpose of the Study:
- To investigate the recovery of auditory function in neonatal chicks after intense sound exposure.
- To analyze changes in auditory threshold sensitivity and response amplitude.
- To correlate electrophysiological findings with known mechanisms of cochlear damage and repair.
Main Methods:
- Exposure of neonatal chicks to a 0.9 kHz tone at 120 dB SPL for 48 hours.
- Recording evoked potentials from the nucleus magnocellularis to assess auditory function.
- Measuring threshold sensitivity and peak-to-peak response amplitude as a function of stimulus intensity at various post-exposure intervals.
- Analyzing amplitude-intensity growth patterns and comparing them to control animals.
Main Results:
- At 3 days post-exposure, significant recovery of threshold sensitivity was observed, with amplitude-intensity growth rates similar to controls.
- By 10 days post-exposure, a severe threshold shift persisted in mid-range frequencies, accompanied by abnormally rapid amplitude growth.
- These findings suggest a complex pattern of auditory damage and repair, with some functions recovering faster than others.
Conclusions:
- Auditory function in neonatal chicks exhibits partial recovery within days of intense sound exposure.
- Abnormal amplitude-intensity growth observed at later stages indicates ongoing or altered repair processes.
- The study highlights the dynamic nature of auditory system recovery and the utility of evoked potentials in tracking these changes.
Abstract:
The recovery of auditory function at selected intervals following exposure to a 0.9 kHz tone for 48 h at 120 dB SPL is described in neonatal chicks. Evoked potentials recorded from the nucleus magnocellularis were used to measure threshold sensitivity and peak-to-peak response amplitude as a function of stimulus intensity. The relation between evoked-response amplitude and stimulus intensity was nearly linear in control animals. However, at 10 days post exposure, the evoked response in mid-range frequencies showed a severe threshold shift and an abnormally rapid growth in amplitude. At 3 days post exposure, the rate of growth was nearly identical to that measured in control animals and threshold sensitivity showed considerable recovery. Current theories of amplitude-intensity growth and studies of basilar papilla damage and repair following intense sound exposure were applied in the analysis of these results.