Ephrin-A3 is Required for Tonotopic Map Precision and Auditory Functions in the Mouse Auditory Brainstem

We are interested in eph receptors and ephrin ligands as they may play a role in forming the tonotopic map in the auditory system. Our research began with screening Ephrin As in the cochlear nucleus. We assayed ephrin-A3, c-fos inductions, and acoustic-startle responses. These tests tell us what role ephrin-A3 plays and whether mice can distinguish between different frequencies. We found that ephrin-A3 is expressed in a ventral to dorsal gradient. Mice lacking ephrin-A3 have broader tonotopic bands and impaired precision of tonotopic maps. They also fail to discriminate sounds with small frequency changes.