SEASONAL PLASTICITY IN STEROID SENSITIVE NEURAL CIRCUITS

对大脑可塑性的理解是面临的一个重要挑战 今天的神经科学。大脑可塑性指的是这样一个事实 各种各样的经历可以导致长期的变化 成人神经系统的结构和功能。调查如何 如果临床进行大脑干预，这些变化是必不可少的 都是有科学依据的。有各种各样的动物 可用的大脑可塑性模型，通常涉及对大脑的反应 损伤或神经退行性疾病。另一类模型 研究自然发生的大脑变化，以响应显著 环境刺激，如那些调节季节性变化时间的刺激 繁殖(如光周期)。人的大脑的季节性变化 鸣禽，如金丝雀(Serinus Canaria)，就是这样的例子 改变。参与发声控制改变的脑核团体积 从季节上看，睾酮可以促进神经元生长，甚至 调节神经发生的发生。然而，完整的 从光周期变化到基因修饰的因果联系 形态还没有建立起来。此外，睾丸素是 在诱导大脑形态变化方面根本不是同样有效 一年中的时间和传入神经输入会影响类固醇 行动。这项提案由五个部分组成；在第一部分，目标是 发声控制的去甲肾上腺素能神经支配特征 作为后续功能的必要前奏的原子核[Exps 1-4] 关于这一传入输入在调制中的作用的研究 大脑的季节性变化。第二节涉及对 金丝雀可塑性的光周期和内分泌控制 发声控制电路[经验5-6]。变异的生理原因 睾酮的有效性将在第三节[Exps]中进行调查 7-8]。第四节将调查去甲肾上腺素能传入到 发声控制核团在光周期或激素作用下的变化 操纵[Exps 9-11]，第五节专门用于调查 季节性/睾丸素是否会引起神经细胞形态的改变 牛群的控制核依赖于 去甲肾上腺素能传入传入[Exp 12]。第六节的目标[Exp 13]的目的是调查季节性/睾丸素是否会引起 神经底物对类固醇作用的反应性 大脑依赖于去甲肾上腺素能输入的存在。 鸣禽大脑的季节性变化提供了一个独特的模型系统 研究自然产生的刺激如何改变大脑形态。

The understanding of brain plasticity is an important challenge facing the neurosciences today. Brain plasticity refers to the fact that experiences of various sorts can lead to enduring changes in the structure and function of the adult nervous system. Investigating how these changes are regulated is essential if clinical brain interventions are to have a scientific underpinning. There are a variety of animal models of brain plasticity available, often involving responses to brain damage or neurodegenerative diseases. Another class of models investigates brain changes that occur naturally in response to salient environmental stimuli such as those regulating the timing of seasonal breeding (e.g. photoperiod). Seasonal changes in the brain of songbirds, such as canaries (Serinus canaria), are an example of such changes. The volume of brain nuclei involved in vocal control change seasonally and testoterone can promote neuronal growth and even modulate the occurrence of neurogenesis. However, the complete causal link from photoperiodic changes to the modification of morphology has not been established. Furthermore, testosterone is not equally effective in inducing changes in brain morphology at all times of the year and afferent neural input can influence steroid action. This proposal consists of five sections; in section I the goal is to characterize the noradrenergic innervation of the vocal control nuclei [Exps 1-4] as a necessary prelude for subsequent functional studies of the role played by this afferent input in the modulation of seasonal changes in the brain. Section II concerns the investigation of the photoperiodic and endocrine control of plasticity in the canary vocal control circuit [exps 5-6]. Physiological reasons for the variation in effectiveness of testosterone will be investigated in section III [Exps 7-8]. Section IV will investigate whether the noradrenergic inputs to vocal control nuclei change as a function of photoperiodic or hormonal manipulation [Exps 9-11] and section V is devoted to the investigation of whether seasonal/testosterone-induced changes in the orphology of the bovcal control nuclei are dependent on the presence of noradrenergic afferent inputs [Exp 12]. The goal of section VI [Exp 13] is to investigate whether seasonsal/testosterone-induced changes in the responsiveness of the neural substrate mediating steroid action ni the brain are dependent on the presence of noradrenergic inputs. Seasonal changes in the songbird brain provide a unique model system to study how naturally occurring stimuli can modify brain morphology.