DEVELOPMENTAL CHANGES IN NEURAL CIRCUITS FOR A BEHAVIOR

该项目旨在研究在人类发育过程中， 学习行为的神经基础。斑胸草雀 guttata）将被用作动物模型，其中研究因素 调节发育中和成年脑的结构可塑性，营养 脊椎动物前脑、神经和激素机制的相互作用 一种复杂的习得行为的发展， 神经形态和细胞过程的差异。 1.斑纹草雀 学习在有限的时间内用于通信的声音， 发展，歌曲学习和行为是由定义明确的 神经回路声音的本体感受反馈 肌肉对歌曲的学习从未被评估过，尽管感觉轴突 从发声器官发出的信号终止于三叉神经 道。我们最近发现端脑末端的病变- 三叉神经系统的一个位置扰乱了幼鸟的发声行为 在歌曲学习过程中，但对歌曲模式的维持没有影响 成年鸟类。我们将绘制出精确的轴突连接， 这个端脑核的地形关系，以 确定来自发音器官的传入纤维是否投射到这个区域， 如果是这样，它们是否选择性地终止于必要的区域 正常的发声发育。 2.我们以前已经证明， 歌曲控制系统的主要丘脑继电器最初使 旺盛的投射到其皮质靶核;随后， 靶核及其丘脑输入回归。我们将标记个人 丘脑轴突终端在不同的发展阶段，以 确定单端心轴是否膨胀和收缩， 最近在视觉系统中得到了证实， 这些事件的时间与自然发生的细胞死亡相关， 这个回路对发声行为的影响程度。我们将 也损伤丘脑核以检查诱导的细胞死亡- 也就是说，我们会问传入输入是否是神经元 在发育中和成年动物的靶核中的存活。 3. 我们已经发现，细胞分裂是高得多， 在晚期， 孵化后的发育阶段。这是第一次展示一个 脊椎动物大脑神经发生的性别差异，并表明 发声行为背后的神经回路中的性别二态性可能 通过调节神经元增殖而出现。我们将开始探索 通过研究性激素在细胞中的作用， 端脑的分裂

This project is designed to study morphological and functional changes in the neural substrate for a learned behavior. Zebra finches (Poephila guttata) will be used as an animal model in which to investigate factors regulating structural plasticity in developing and adult brain, trophic interactions in vertebrate fore brain, neural and hormonal mechanisms underlying the development of a complex learned behavior, and sex differences in neural morphology and cellular processes. 1. Zebra finches learn the sounds used for communication during a restricted period of development, and song learning and behavior are controlled by well-defined neural circuits. The contribution of proprioceptive feedback from vocal muscles to song learning has never been evaluated, although sensory axons from the vocal organ are known to terminate throughout the trigeminal tract. We have recently shown that lesions of the telencephalic end- station of the trigeminal system disrupt vocal behavior in juvenile birds during song learning, but have no effect on maintenance of song patterns by adult birds. We will map out the precise axonal connections and topographic relationships of this telencephalic nucleus in order to determine if afferent fibers from the vocal organ project to this area, and if so whether they terminate selectively in a region that is necessary for normal vocal development. 2. We have previously demonstrated that the major thalamic relay of the song-control system initially makes an exuberant projection to its cortical target nucleus; subsequently both the target nucleus and its thalamic input regress. We will label individual thalamic axon terminals at different stages of development in order to determine whether single terminal arbors are expanding and regressing, as has recently been demonstrated in the visual system, and whether the timing of these events correlates with naturally-occurring cell death or the extent to which this circuit contributes to vocal behavior. We will also lesion this thalamic nucleus in order to examine induced cell death - i.e., we will ask whether afferent input is necessary for neuronal survival in the target nucleus in both developing and adult animals. 3. We have discovered that cell division is much higher in the germinal epithelium of the telencephalon in males than in females during late stages of post-hatch development. This is the first demonstration of a robust sex difference in neurogenesis in vertebrate brain, and suggests that sex dimorphisms in neural circuits underlying vocal behavior may emerge via regulation of neuronal proliferation. We will begin to explore this remarkable result by investigating the role of sex hormones on cell division in the telencephalon.