Bio-Imaging Lab, University of Antwerp, Belgium.
Laboratory of Comparative Endocrinology, KU Leuven, Belgium.
Horm Behav. 2020 Feb;118:104639. doi: 10.1016/j.yhbeh.2019.104639. Epub 2019 Nov 30.
Adult neuroplasticity in the song control system of seasonal songbirds is largely driven by photoperiod-induced increases in testosterone. Prior studies of the relationships between testosterone, song performance and neuroplasticity used invasive techniques, which prevent analyzing the dynamic changes over time and often focus on pre-defined regions-of-interest instead of examining the entire brain. Here, we combined (i) in vivo diffusion tensor imaging (DTI) to assess structural neuroplasticity with (ii) repeated monitoring of song and (iii) measures of plasma testosterone concentrations in thirteen female photosensitive starlings (Sturnus vulgaris) who received a testosterone implant for 3 weeks. We observed fast (days) and slower (weeks) effects of testosterone on song behavior and structural neuroplasticity and determined how these effects correlate on a within-subject level, which suggested separate contributions of the song motor and anterior forebrain pathways in the development of song performance. Specifically, the increase in testosterone correlated with a rapid increase of song rate and RA volume, and with changes in Area X microstructure. After implant removal, these variables rapidly reverted to baseline levels. In contrast, the more gradual improvement of song quality was positively correlated with the fractional anisotropy values (DTI metric sensitive to white matter changes) of the HVC-RA tract and of the lamina mesopallialis, which contains fibers connecting the song control nuclei. Thus, we confirmed many of the previously reported testosterone-induced effects, like the increase in song control nuclei volume, but identified for the first time a more global picture of the spatio-temporal changes in brain plasticity.
成年鸣禽的 song 控制系统中的神经可塑性在很大程度上是由光周期诱导的睾酮增加驱动的。先前关于睾酮、song 表现和神经可塑性之间关系的研究使用了侵入性技术，这些技术阻止了对随时间推移的动态变化进行分析，并且通常侧重于预定义的感兴趣区域，而不是检查整个大脑。在这里，我们结合了（i）体内扩散张量成像（DTI）来评估结构神经可塑性，以及（ii）重复监测 song 行为和（iii）十三只雌性感光星雀（Sturnus vulgaris）的血浆睾酮浓度测量值，这些星雀接受了 3 周的睾酮植入物治疗。我们观察到睾酮对 song 行为和结构神经可塑性的快速（天）和较慢（周）影响，并确定了这些影响在个体水平上的相关性，这表明 song 运动和前脑通路的单独贡献在 song 表现的发展中。具体而言，睾酮的增加与 song 率和 RA 体积的快速增加以及 Area X 微观结构的变化相关。植入物去除后，这些变量迅速恢复到基线水平。相比之下，song 质量的更渐进的改善与 HVC-RA 束和包含连接 song 控制核的纤维的中脑薄板的层状 mesopallialis 的分数各向异性值（DTI 度量敏感于白质变化）呈正相关。因此，我们证实了许多先前报道的睾酮诱导的效应，例如 song 控制核体积的增加，但首次确定了大脑可塑性的时空变化的更全面的图景。
