Ball Gregory F, Auger Catherine J, Bernard Daniel J, Charlier Thierry D, Sartor Jennifer J, Riters Lauren V, Balthazart Jacques
Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2686, USA.
Ann N Y Acad Sci. 2004 Jun;1016:586-610. doi: 10.1196/annals.1298.043.
Birdsong, in non-tropical species, is generally more common in spring and summer when males sing to attract mates and/or defend territories. Changes in the volumes of song control nuclei, such as HVC and the robust nucleus of the arcopallium (RA), are observed seasonally. Long photoperiods in spring stimulate the recrudescence of the testes and the release of testosterone. Androgen receptors, and at times estrogen receptors, are present in HVC and RA as are co-factors that facilitate the transcriptional activity of these receptors. Thus testosterone can act directly to induce changes in nucleus volume. However, dissociations have been identified at times among long photoperiods, maximal concentrations of testosterone, large song control nuclei, and high rates of song. One explanation of these dissociations is that song behavior itself can influence neural plasticity in the song system. Testosterone can act via brain-derived neurotrophic factor (BDNF) that is also released in HVC as a result of song activity. Testosterone could enhance song nucleus volume indirectly by acting in the preoptic area, a region regulating sexual behaviors, including song, that connects to the song system through catecholaminergic cells. Seasonal neuroplasticity in the song system involves an interplay among seasonal state, testosterone action, and behavioral activity.
在非热带物种中，鸟鸣通常在春季和夏季更为常见，此时雄性通过鸣叫来吸引配偶和/或保卫领地。人们观察到，诸如HVC和古纹状体粗核（RA）等鸣叫控制核团的体积会随季节发生变化。春季较长的光照周期会刺激睾丸的再生以及睾酮的释放。HVC和RA中存在雄激素受体，有时也存在雌激素受体，以及促进这些受体转录活性的辅助因子。因此，睾酮可以直接作用于诱导核团体积的变化。然而，有时在长光照周期、睾酮的最大浓度、较大的鸣叫控制核团和较高的鸣叫频率之间发现了分离现象。对这些分离现象的一种解释是，鸣叫行为本身可以影响鸣叫系统中的神经可塑性。睾酮可以通过脑源性神经营养因子（BDNF）起作用，BDNF也是由于鸣叫活动而在HVC中释放的。睾酮可以通过作用于视前区间接增强鸣叫核团的体积，视前区是一个调节包括鸣叫在内的性行为的区域，它通过儿茶酚胺能细胞与鸣叫系统相连。鸣叫系统中的季节性神经可塑性涉及季节性状态、睾酮作用和行为活动之间的相互作用。
