The impact of deafness to the survival of the newborn cells in the brain of juvenile white-rumped munia, Lonchura striata.

In white-rumped munia, early auditory experience is critical for normal song development. New neurons are constantly added to the telencephalon in juveniles. We examined the potential role of auditory experience in regulating the developmental changes in the song nuclei and the survival of newborn cells. We chose two special days, postnatal day 23 and 37, at which we deafened the birds through bilateral cochlea removal. All birds were injected with the cell birth marker BrdU two weeks before the lesion surgeries, and then were killed two weeks or one month later. The BrdU-positive cells were distributed throughout the brain, including the high vocal center (HVC), Lobus parolfactorius and the ventricle zone (VZ) in telencephalon, the granular cell layer (GCL) of cerebellum. Moreover, these BrdU-positive cells in the GCL could self-renew. However, the nucleus robustus archistriatalis (RA) did not sprout new neurons in juvenile. In telencephalon except the VZ, 41 percent of BrdU-positive cells were NeuN-positive, too. Deafness had no significant effect on development of HVC and RA, the distribution of new cells, and the survival of new cells in telencephalon. From these data, we propose that auditory deprivation could not affect the survival of new cells of telencephalon within one month. Surprisingly, we found deafness had a complex and dramatic effect on the number of new cells in cerebellum. Deafness at postnatal day 23 could increase the number of new cells in the GCL, while deafness at postnatal day 37 decreased the number.