Neuroendocrine control of seasonal phenotypic plasticity in birds

大多数生物都表现出季节性变化，以应对其环境中可预测的变化。季节性繁殖的鸣禽表现出极大的可塑性。 鸟类在不同季节调整社会行为、繁殖和运动。 它们在大脑、生殖生理学和其他系统中表现出高度的可塑性。 一只鸟的健康关键取决于它是否有能力适当地把握季节性行为和生理变化的时间。我的研究项目的一个中心主题是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。 我在未来5年研究的主要目标将是探索大脑和行为季节性变化的环境生理学。 该方案的主要假设包括1.季节性重演个体发育：大脑发育的细胞机制受到调节，以诱导季节性神经可塑性。雄激素、雌激素和非甾体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，它们的影响在不同的季节会有所不同.作为运动综合征的一部分，个体之间的延迟调节、迁移行为和扩散是相关的。由光周期同步的内源性生物钟控制着迁徙的时间，但性腺雄激素加速和同步春季迁徙的躁动，抑制秋季迁徙的躁动。对捕食者暗示和人造毒素等压力源的反应会因季节而异。我将通过一个实验室和实地实验研究项目来阐述上述假设。使用一套发育神经可塑性的标志物，目前正在我的实验室开发中，我将探索大脑可塑性的季节性和发育机制之间的相似性，通过比较一年中不同时间的大脑，并遵循已知驱动行为季节性变化的激素的操纵。我将操纵类固醇激素来确定它们如何控制大脑解剖结构的季节性变化。我将评估性腺类固醇激素如何影响迁移强度和方向的差异春季和秋季迁移使用激素去除和替代实验和监测行为在圈养和在现场使用遥测和远程跟踪。 我将测试大脑对捕食者线索的反应，以及对甲基汞的生理反应如何随季节变化。结合起来，这些研究线创建了一个独特的综合研究计划，探索如何调节季节性表型可塑性。 具体来说，我将探索环境因素如何通过激素信号影响大脑和行为的季节性变化，这对于预测鸟类如何科普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.