Normal brainstem auditory evoked potentials in Pax5-deficient mice despite morphologic alterations in the auditory midbrain region.

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