Ontogenetic changes in the pattern of XXXX accumulation in song-control nuclei of male zebra finches.

@entity1 @entity586 @entity342 @entity12128
The present study examines the development of @entity342 accumulation in cells of two brain nuclei that are involved in controlling vocal behavior in zebra finches ( @entity12128 ). HVc (caudal nucleus of the ventral hyperstriatum) is involved with vocal production in adult birds, and @entity1 (magnocellular nucleus of the anterior neostriatum) is involved with the initial ability to learn song. In both of these nuclei there is an increase in the proportion of cells that are labeled by systemic injections of tritiated @entity586 in juvenile male zebra finches during the time when production of song is becoming stereotyped (25-60 days). Within @entity1 there is an overall loss of cells during this time, such that the absolute number of @entity342 target cells in @entity1 remains at a constant level. However, it does not appear to be the case that unlabeled cells are selectively lost from @entity1 . Rather it appears that both labeled and unlabeled cells are lost, and the absolute number of labeled cells is maintained at a constant level via recruitment of additional labeled cells from the unlabeled population (i.e., some @entity1 cells that are unlabeled in young birds become labeled in older birds). In line with this hypothesis, there is a large increase in the density of labeling in individual @entity1 cells, indicating that these cells have an enhanced ability to concentrate @entity342 . In contrast to the situation in @entity1 , there is an increase in the overall number of cells within HVc during this time; this increase in total cell number combines with the increased proportion of labeled cells such that the absolute number of @entity342 target cells in HVc increases threefold. The ability of individual HVc cells to accumulate @entity342 remains constant. The relationship of these changes in the pattern of @entity342 accumulation to other aspects of neural and behavioral development related to song in zebra finches are discussed.
