Smith G T, Brenowitz E A, Wingfield J C
Department of Zoology, University of Washington, Seattle 98195, USA.
J Comp Neurol. 1997 May 12;381(3):253-61. doi: 10.1002/(sici)1096-9861(19970512)381:3<253::aid-cne1>3.0.co;2-1.
Bird song is controlled by a discrete network of brain nuclei. The size of several song control nuclei changes seasonally in many seasonally breeding songbird species. Reports of seasonal changes in the size of song nuclei have relied primarily on Nissl stains to define the borders of these regions. Recent studies found that the size of the song nucleus higher vocal center (HVC) in male canaries did not change seasonally when its borders were defined by histological markers other than Nissl staining. We used three labels to define the borders of the HVC in male Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii): Nissl staining, the distribution of acetylcholinesterase-positive neuropil, and the distribution of neurons projecting to another song nucleus, area X. The HVC was larger in males exposed to a breeding photoperiod and testosterone concentrations than in males exposed to a nonbreeding photoperiod and testosterone concentrations, regardless of which of these three methods was used to define the borders of the HVC. This result suggests that seasonal changes in the Nissl-defined borders of the HVC reflect changes in the distribution of physiologically relevant markers of the nucleus and are not merely artifacts of the Nissl-staining method.
鸟鸣受大脑核团的一个离散网络控制。在许多季节性繁殖的鸣禽物种中，几个鸣唱控制核团的大小会随季节变化。关于鸣唱核团大小季节性变化的报告主要依赖尼氏染色来界定这些区域的边界。最近的研究发现，当用尼氏染色以外的组织学标记来界定边界时，雄性金丝雀的高级发声中枢（HVC）核团大小并不会随季节变化。我们使用了三种标记来界定雄性甘贝尔白冠雀（Zonotrichia leucophrys gambelii）的HVC边界：尼氏染色、乙酰胆碱酯酶阳性神经纤维的分布以及投射到另一个鸣唱核团X区的神经元分布。无论使用这三种方法中的哪一种来界定HVC的边界，暴露于繁殖光周期和睾酮浓度下的雄性HVC都比暴露于非繁殖光周期和睾酮浓度下的雄性更大。这一结果表明，尼氏染色界定的HVC边界的季节性变化反映了该核团生理相关标记分布的变化，而不仅仅是尼氏染色方法造成的假象。
