Noise and the young mouse: Genotype modifies the sensitive period for effects on cochlear physiology and audiogenic seizures


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Abstract

Examined the correspondence between the critical period, during which acoustic trauma will profoundly alter subsequent auditory behavior, and the broader sensitive period, during which acoustic trauma is most damaging to cochlear functions in the young ear, using 133 C57BL/6 and 183 CBA mice (aged 12–54 days) as Ss. Ss were exposed to 2 min of 124-db octave band noise (8–26 kHz). A noninvasive electrocochleographic technique was used to assess cochlear microphonic (CM) and action potential (AP) thresholds in exposed Ss and nonexposed littermate controls. Noise had no effect on 12-day-old CBA Ss but produced a maximal threshold elevation at 30–36 days in 54-day-old Ss. Susceptibility to audiogenic seizures in exposed CBA Ss was greatest at the peak of the sensitive period for cochlear damage. 12-day-old C57BL/6 Ss were also unaffected by noise exposure; 36-day-old C57BL/6 Ss had maximal AP (23 db) and CM (17 db) threshold; elevations and 54-day-old C57BL/6 Ss had an 18-db elevation of the AP; and their CM was no longer affected. It is concluded that both genotypes have a sensitive period for the effects of noise trauma on CM and AP thresholds: CBA has a sensitive period for acoustic priming for audiogenic seizures, and C57BL/6 has a critical period for acoustic priming. (48 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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