Auditory brainstem responses in neonatally sound deprived CBA/J mice

Abstract

Auditory brainstem responses (ABR) from ten normal (3 males, 7 females) and ten environmentally sound deprived CBA/J mice (6 males, 4 females) were elicited by 30 dB HL click stimuli delivered via specially constructed, matched insert earphones. The mice were tested at 44-49 days of age under chloral hydrate sedation using an electrode montage of vertex/linked bilateral bullae/presacrum. The deprived mice were killed immediately after testing and serial transverse sections were prepared from their brains. Examination of globular cells of the ventromedial ventral cochlear nuclei revealed significantly smaller cross-sectional areas of these cells than in previously studied normal mice. Although monaural thresholds did not differ between the two groups, significantly shorter mean latencies were observed in the ABRs of the sound deprived group in wave I as well as in the interpeak latencies of the later ABR components (I-IV, I-V, and III-V). These electrophysiologic alterations in brainstem conduction presumably reflect the anatomical changes demonstrated in neonatally sound deprived mice.