Department of Biomedical Sciences, Bio-Imaging Lab, University of Antwerp, Antwerpen, Belgium.
NEURO Research Centre of Excellence, University of Antwerp, Antwerpen, Belgium.
J Exp Zool A Ecol Integr Physiol. 2022 Dec;337(9-10):967-984. doi: 10.1002/jez.2650. Epub 2022 Aug 21.
Seasonality in songbirds includes not only reproduction but also seasonal changes in singing behavior and its neural substrate, the song control system (SCS). Prior research mainly focused on the role of sex steroids on this seasonal SCS neuroplasticity in males. In this review, we summarize the advances made in the field of seasonal neuroplasticity by applying in vivo magnetic resonance imaging (MRI) in male and female starlings, analyzing the entire brain, monitoring birds longitudinally and determining the neuronal correlates of seasonal variations in plasma hormone levels and song behavior. The first MRI studies in songbirds used manganese enhanced MRI to visualize the SCS in a living bird and validated previously described brain volume changes related to different seasons and testosterone. MRI studies with testosterone implantation established how the consequential boost in singing was correlated to structural changes in the SCS, indicating activity-induced neuroplasticity as song proficiency increased. Next, diffusion tensor MRI explored seasonal neuroplasticity in the entire brain, focusing on networks beyond the SCS, revealing that other sensory systems and even the cerebellum, which is important for the integration of sensory perception and song behavior, experience neuroplasticity starting in the photosensitive period. Functional MRI showed that olfactory, and auditory processing was modulated by the seasons. The convergence of seasonal variations in so many sensory and sensorimotor systems resembles multisensory neuroplasticity during the critical period early in life. This sheds new light on seasonal songbirds as a model for unlocking the brain by recreating seasonally the permissive circumstances for heightened neuroplasticity.
鸟类的季节性不仅包括繁殖，还包括其歌唱行为及其神经基质——歌唱控制系统 (SCS) 的季节性变化。先前的研究主要集中在性激素对雄性季节性 SCS 神经可塑性的作用上。在这篇综述中，我们总结了通过应用活体磁共振成像 (MRI) 在雄性和雌性椋鸟中研究季节性神经可塑性的进展，分析整个大脑，对鸟类进行纵向监测，并确定季节性血浆激素水平和歌唱行为变化的神经元相关性。在鸟类中进行的第一项 MRI 研究使用锰增强 MRI 来可视化活体鸟类的 SCS，并验证了先前描述的与不同季节和睾酮相关的大脑体积变化。用睾酮植入物进行的 MRI 研究确立了歌唱的继发增强与 SCS 的结构变化之间的相关性，表明随着歌唱能力的提高，活动诱导的神经可塑性。接下来，扩散张量 MRI 探索了整个大脑的季节性神经可塑性，重点关注 SCS 以外的网络，揭示了其他感觉系统，甚至小脑，对感觉感知和歌唱行为的整合很重要，也经历了神经可塑性，从光敏感期开始。功能 MRI 显示嗅觉和听觉处理受季节影响。如此多的感觉和感觉运动系统的季节性变化的融合类似于生命早期关键期的多感觉神经可塑性。这为通过重现增强神经可塑性的许可条件来揭示大脑的季节性鸣禽提供了新的视角。
