Changes in cochlear microphonic sensitivity after priming C57BL/6j mice at various ages for audiogenic seizures.

Groups of mice were briefly exposed to a one-octave band of noise at 14, 18, 28, 38, or 58 days of age. Five days later the groups were divided, and some mice were behaviorally tested for audiogenic seizures by reexposing them to the same sound. The round window cochlear microphonic potential was measured in the remaining animals and compared with that observed in unprimed control subjects. Seizure behavior occurred in all animals primed on Day 18 but rarely for subjects in the other age groups. Cochlear microphonic threshold curves in mice primed on Day 18 showed a 30-dB loss in sensitivity, while all other primed groups showed little change. These data were discussed in terms of the "disuse-supersensitivity" hypothesis previously proposed to account for the physiological effects of priming in mice.