Androgen control of vocal control region volumes in a wild migratory songbird (Junco hyemalis) is region and possibly age dependent
✍ Scribed by Gulledge, Cynthia C. ;Deviche, Pierre
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 389 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0022-3034
No coin nor oath required. For personal study only.
✦ Synopsis
Previous laboratory studies have androgen levels. In adolescent males, however, area shown that photoperiodic adult songbirds experience X volume was the same as in breeding adults. Thus, seasonal variations in singing frequency that correlate with plasma androgen levels, as well as changes in area X size in adolescent male juncos may be testosterthe brain regions that control singing (vocal control one independent. The seasonal pattern of robust nuregions). The present study investigates naturally occleus of the archistriatum volume was similar to that curring seasonal changes in the sizes of these regions of the HVC. The volumes of neither the magnocellular in a wild migratory species (dark-eyed junco, Junco nucleus of the anterior neostriatum nor the nucleus hyemalis), with samples from adolescence to postrotundus, a control region, differed seasonally. Casbreeding fall migration. In adult males, the volumes tration of breeding adult males caused both area X of the vocal control regions area X and the higher and HVC volumes to decrease compared to castrated vocal center (HVC) were large during the breeding controls with testosterone replacement, indicating that season when birds were singing and androgen levels maintenance of these two region volumes is testosterwere high, and decreased in size after the breeding one dependent in adults. ᭧ 1997 John Wiley & Sons, Inc. J season when singing had stopped and androgen levels Neurobiol 32: 391-402, 1997. were low. HVC volume in adolescent males caught in