Department of Psychology, T.I.M.E.S, University of Houston, Houston, TX 77204, USA; Department of Biology and Biochemistry, University of Houston, Houston, TX 77004, USA; Department of Psychology, Neural and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA.
GIGA Neuroscience, University of Liège, 4000 Liège, Belgium.
Horm Behav. 2024 Sep;165:105611. doi: 10.1016/j.yhbeh.2024.105611. Epub 2024 Jul 31.
During breeding when testosterone concentrations are high, male songbirds that are open-ended vocal learners like canaries (Serinus canaria) tend to produce a stable, stereotyped song that facilitates mate attraction or territory defense. Outside breeding contexts, song becomes more variable. The neuroendocrine mechanisms controlling this vocal variability across seasons are not entirely clear. We tested whether androgen signaling within the lateral magnocellular nucleus of the anterior nidopallium (LMAN), a cortical-like brain region of the vocal control system known as a vocal variability generator, plays a role in seasonal vocal variability. We first characterized song in birds housed alone on a short day (SD) photoperiod, which simulates non-breeding conditions. Then, cannulae filled with the androgen receptor (AR) blocker flutamide or left empty as control were implanted bilaterally in LMAN. Birds were then transferred to long days (LD) to simulate the breeding season and song was analyzed again. Blocking AR in LMAN increased acoustic variability of song and the acoustic variability of syllables. However, blocking AR in LMAN did not impact the variability of syllable usage nor their sequencing in LD birds, song features that are controlled by androgen signaling in a somatosensory brain region of the vocal control system called HVC. These findings highlight the multifactorial, non-redundant actions of steroid hormones in controlling complex social behaviors such as birdsong. They also support the hypothesis that LMAN is a key brain area for the effects of testosterone on song plasticity both seasonally in adults and during the song crystallization process at sexual maturity.
在繁殖期，当睾丸激素浓度较高时，像金丝雀（Serinus canaria）这样的无限制声乐学习者的雄性鸣禽往往会发出稳定、刻板的歌声，从而促进求偶或领地防御。在繁殖期以外的时间，歌声变得更加多变。控制这种季节性声音变化的神经内分泌机制尚不完全清楚。我们测试了雄激素信号在外侧巨细胞核的前部中脑（LMAN）中的作用，LMAN 是一个类似于大脑皮层的发声控制系统的区域，被称为发声变异性发生器，它是否在季节性发声变异性中发挥作用。我们首先描述了在短日（SD）光周期下独居的鸟类的歌声，这模拟了非繁殖条件。然后，将充满雄激素受体（AR）阻滞剂氟他胺的套管或空套管作为对照物植入 LMAN 的双侧。然后，将鸟类转移到长日（LD）以模拟繁殖季节，并再次分析歌声。LMAN 中的 AR 阻断增加了歌声的可变性和音节的可变性。然而，LMAN 中的 AR 阻断并没有影响 LD 鸟类中音节使用的可变性或它们的排序，这些特征是由发声控制系统中的一个躯体感觉脑区 HVC 中的雄激素信号控制的。这些发现强调了类固醇激素在控制复杂社会行为（如鸟鸣）中的多因素、非冗余作用。它们还支持了 LMAN 是雄激素对季节性成年期和性成熟时歌曲可塑性影响的关键大脑区域的假设。
