NORMAL BRAIN-STEM AUDITORY-EVOKED POTENTIALS IN PAX5-DEFICIENT MICE DESPITE MORPHOLOGIC ALTERATIONS IN THE AUDITORY MIDBRAIN REGION

The inferior colliculus in the auditory midbrain region is underdevelo ped near the midline in mice lacking the transcription factor Pax5. We have now tested whether hearing deficiencies occur in these mice by m easuring auditory evoked brainstem responses. However, the responses a nd audiograms obtained in homozygous Pax5 mutants did not differ from those of control mice, suggesting that the observed morphologic altera tions of the inferior colliculus do not affect hearing, as judged by a uditory evoked potential recordings. The only detectable effect of the Pax5 mutation was a delay in the development of the auditory sensitiv ity and response latency that correlates with the general growth retar dation observed in these mice.