Tramontin A D, Brenowitz E A
Department of Zoology, University of Washington, Box 351800, Seattle, Washington 98195-1800, USA.
J Neurobiol. 1999 Sep 5;40(3):316-26. doi: 10.1002/(sici)1097-4695(19990905)40:3<316::aid-neu4>3.0.co;2-s.
Adult songbirds can incorporate new neurons into HVc, a telencephalic song control nucleus. Neuronal incorporation into HVc is greater in the fall than in the spring in adult canaries (open-ended song learners) and is temporally related to seasonal song modification. We used the western song sparrow, a species that does not modify its adult song, to test the hypothesis that neuronal incorporation into adult HVc is not seasonally variable in age-limited song learners. Wild song sparrows were captured during the fall and the spring, implanted with osmotic pumps containing [3H]thymidine, released onto their territories, and recaptured after 30 days. The density, proportion, and number of new HVc neurons were all significantly greater in the fall than in the spring. There was also a seasonal change in the incorporation of new neurons into the adjacent neostriatum that was less pronounced than the change in HVc. This is the first study of neuronal recruitment into the song control system of freely ranging wild songbirds. These results indicate that seasonal changes in HVc neuronal incorporation are not restricted to open-ended song learners. The functional significance of neuronal recruitment into HVc therefore remains elusive.
成年鸣禽能够将新的神经元整合到HVC中，HVC是一个端脑鸣叫控制核团。在成年金丝雀（开放式鸣叫学习者）中，秋季神经元整合到HVC中的情况比春季更明显，且在时间上与季节性鸣叫变化相关。我们使用了西部歌雀，这是一种成年后不会改变其鸣叫的物种，来检验在年龄受限的鸣叫学习者中，成年HVC中神经元整合不存在季节性变化的假说。在秋季和春季捕获野生歌雀，给它们植入含有[3H]胸腺嘧啶核苷的渗透泵，放归到它们的领地，30天后重新捕获。秋季新的HVC神经元的密度、比例和数量均显著高于春季。相邻新纹状体中整合新神经元的情况也存在季节性变化，但其变化程度不如HVC明显。这是对自由放养的野生鸣禽鸣叫控制系统中神经元募集的首次研究。这些结果表明，HVC神经元整合的季节性变化并不局限于开放式鸣叫学习者。因此，神经元募集到HVC中的功能意义仍然难以捉摸。
