SEASONAL PLASTICITY IN STEROID SENSITIVE NEURAL CIRCUITS

对大脑可塑性的理解是一个重要的挑战， 今天的神经科学 大脑可塑性指的是 各种各样的经历可能会导致持久的变化 成人神经系统的结构和功能。 研究如何 如果临床脑干预， 都需要有科学的支撑 有各种各样的动物 大脑可塑性的模型，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 研究大脑的变化，自然发生的反应，突出 环境刺激，如调节季节性变化的时间的刺激， 繁殖（例如光周期）。 大脑的季节性变化 鸣禽，如金丝雀（Serinus canaria），就是这样的例子。 变化 发声控制变化涉及的脑核团体积 季节性和睾酮可以促进神经元的生长，甚至 调节神经发生。 然而，完整的 从光周期变化的因果关系的修改 形态学尚未建立。 此外，睾酮是 在诱导大脑形态变化方面并不同样有效 一年中的时间和传入神经输入可以影响类固醇 行动上 该提案由五个部分组成;第一部分的目标是 描述发声控制的去甲肾上腺素能神经支配 核[实验1 - 4]作为后续功能的必要前奏 研究了这种传入输入在调制中所起的作用， 大脑的季节性变化 第二节调查 光周期和内分泌对金丝雀可塑性的控制 语音控制电路[实验5 - 6]。 变异的生理原因 睾酮的有效性将在第III节[实验 7 - 8]。 第四节将研究去甲肾上腺素能输入是否 发声控制核团的变化是光周期或激素的函数 操纵[实验9 - 11]和第五节致力于调查 是否季节性/睾酮诱导的形态学变化， bovcal控制核依赖于 去甲肾上腺素能传入输入[实验12]。 第六节的目标[Exp 13]是为了研究季节性/睾酮诱导的变化， 调节类固醇作用的神经基质的反应性 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 研究自然发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.