Neuroendocrine control of seasonal phenotypic plasticity in birds

大多数生物体表现出季节性变化，以响应其环境中可预测的变化。季节性繁殖的鸣禽表现出极大程度的可塑性。鸟类在不同季节调整社会行为、繁殖和活动。它们在大脑、生殖生理和其他系统中表现出高度的可塑性。鸟类的健康关键取决于它对行为和生理的季节性变化进行适当计时的能力。我的研究计划的一个中心主题是研究鸟类如何利用环境线索来调节生理、神经生物学和行为的季节性变化。我未来5年的主要研究目标将是探索大脑和行为季节性变化的环境生理学。该计划的主要假设包括1。季节性概括了个体发育：大脑发育的细胞机制被调节以诱导季节性神经可塑性。雄激素、雌激素和非类固醇因子对季节性神经发生和其他形式的季节性大脑可塑性有不同的影响，它们的影响因季节而异。作为运动综合征的一部分，睾酮调节、迁移行为和散布在个体之间是相关的。被光周期同步的内源性时钟控制着迁徙的时间，而性腺激素则加速和同步春季迁徙的躁动，抑制秋季的迁徙躁动。对捕食者暗示和人造毒素等应激源的反应会因季节而异。我将通过实验室和基于现场的实验研究计划来解决上述假设。使用我实验室目前正在开发的一套发育神经可塑性标记物，我将通过比较一年中不同时间的大脑，并跟踪操纵已知的推动行为季节性变化的激素，来探索大脑可塑性的季节性和发育性机制之间的相似性。我将操纵类固醇激素，以确定它们如何控制大脑解剖的季节性变化。我将通过激素清除和替代实验以及利用遥测和远程跟踪监测圈养和野外行为，来评估性腺类固醇如何影响春季和秋季迁徙之间的迁徙强度和方向的差异。我将测试大脑对捕食者暗示的反应，以及对甲基汞的生理反应随着季节的变化。这些研究路线结合在一起，创造了一个独特的综合研究计划，探索季节性表型可塑性是如何受到调节的。具体地说，我将探索环境因素如何通过荷尔蒙信号影响大脑和行为的季节性变化，这对于预测鸟类如何应对不断变化的环境至关重要。

Most organisms exhibit seasonal changes in response to predictable changes in their environment. Seasonally-breeding songbirds show a tremendous degree of such plasticity. Birds adjust social behaviour, reproduction and movement across seasons. They exhibit high degrees of plasticity in the brain, reproductive physiology, and other systems. A bird's fitness depends critically on its ability to appropriately time seasonal changes in behaviour and physiology. A central theme of my research program addresses how birds use environmental cues to regulate seasonal changes in physiology, neurobiology and behaviour. The primary objective of my research over the next 5 years will be to explore the environmental physiology of seasonal changes in brain and behaviour. The primary hypotheses of this program include1. Seasonality recapitulates ontogeny: the cellular mechanisms underlying brain development are regulated to induce seasonal neural plasticity.2. Androgens, estrogens, and non-steroidal factors, have differential effects on seasonal neurogenesis and other forms of seasonal brain plasticity, and their effects will vary across different seasons.3. Testosterone regulation, migration behaviour, and dispersal are correlated among individuals as part of a movement syndrome.4. Endogenous clocks that are synchronized by photoperiod control the timing of migration, but gonadal androgens accelerate and synchronize spring migratory restlessness and inhibit fall migratory restlessness.5. Responses to stressors such as predator cues and man-made toxins will vary seasonally. I will address the above hypotheses through a program of laboratory and field-based experimental studies. Using a suite of markers of developmental neural plasticity currently under development in my lab I will explore the similarities between seasonal and developmental mechanisms of brain plasticity by comparing brains from different times of year and following manipulation of hormones known to drive seasonal changes in behaviour. I will manipulate steroid hormones to determine how they control seasonal changes in brain anatomy. I will assess how gonadal steroids affect differences in migratory intensity and orientation between spring and fall migration using hormone removal and replacement experiments and monitoring behaviour in captivity and in the field using telemetry and remote tracking. I will test how brain responses to predator cues, and physiological responses to methylmercury change with the seasons. Combined, these lines of research create a uniquely integrative research program that explores how seasonal phenotypic plasticity is regulated. Specifically, I will explore how environmental factors affect seasonal changes in brain and behaviour via hormone signals, which is critical to predicting how birds will cope with changing environments.