The role of myelination in the development of motor control is widely known, but its role in the development of cognitive abilities is less understood. Here, we examined sex differences in the development of myelination of structures and tracts that support song learning and production in songbirds. We collected brains from 63 young male and female zebra finches (Taeniopygia guttata) over four stages of development that correspond to different stages of song learning. Using a myelination marker (myelin basic protein), we measured the development of myelination in three different nuclei of the vocal control system (HVC, RA, and lateral magnocellular nucleus of the anterior nidopallium [LMAN]) and two tracts (HVC-RA and lamina mesopallium ventralis [LMV]). We found that the myelination of the vocal control nuclei and tracts is sex related and male biased. In males, the patterns of myelination were age-dependent, asynchronous in rate and progression and associated with the development of song learning and production. In females, myelination of vocal control nuclei was low or absent and did not significantly change with age. Sex differences in myelination of the HVC-RA tract were large and emerged late in development well after sex differences in the size of vocal control brain regions are established. Myelination of this tract in males coincides with the age of song crystallization. Overall, the changes in myelination in the vocal control areas and tracts measured are region-, age-, and sex-specific and are consistent with sex differences in song development.

中文翻译：

---

斑胸草雀声音控制系统髓鞘形成的性别差异在发育过程中出现相对较晚

髓鞘形成在运动控制发展中的作用广为人知，但其在认知能力发展中的作用却鲜为人知。在这里，我们检查了支持鸣禽歌曲学习和生产的结构和束的髓鞘形成的性别差异。我们收集了 63 只年轻的雄性和雌性斑胸草雀 ( Taeniopygia guttata ) 的大脑) 四个发展阶段对应歌曲学习的不同阶段。使用髓鞘形成标记物（髓鞘碱性蛋白），我们测量了发声控制系统的三个不同核（HVC、RA 和前 nidopallium [LMAN] 的外侧大细胞核）和两个束（HVC-RA 和Lamina mesopallium v​​entralis [LMV]）。我们发现声音控制核和束的髓鞘形成与性别有关，并且偏向男性。在男性中，髓鞘形成的模式与年龄有关，速度和进展不同步，并且与歌曲学习和制作的发展有关。在女性中，声音控制核的髓鞘形成很低或没有，并且没有随着年龄的增长而显着变化。HVC-RA 道髓鞘形成的性别差异很大，并且在声音控制大脑区域大小的性别差异确定后出现在发育后期。雄性该道的髓鞘形成与歌曲结晶的年龄相吻合。总体而言，测量的声音控制区域和束中的髓鞘形成变化是区域、年龄和性别特定的，并且与歌曲发展中的性别差异一致。