NEURAL CHANGES ASSOCIATED WITH CRITICAL LEARNING PERIODS

描述(根据申请者的摘要改编)：鸟鸣学习是一种 研究体验如何影响神经和行为的强大模型 发展。在学习歌唱的过程中，鸟类会记住同种的歌声并使用 听觉反馈来塑造他们的发声，以适应这些存储的模型。这 歌曲学习通常被限制在特定物种的敏感期，并且 这项建议旨在确定鼓励和 限制这种学习。这些研究集中在两个神经事件上， 伴唱学习的密度和发育性变化 N-甲基-D-天冬氨酸(NMDA)谷氨酸受体亚型的药理学， 以及在发声运动通路中大量增加新的电路。 NMDA受体与许多经验依赖的例子有关 神经可塑性及其激活是记忆所必需的 歌曲学习的阶段。行为药理学和高尔基体染色 结合斑纹雀来确定NMDA受体是否激活 促使出现在一个歌区的树突棘的减少 在学习过程中。此外，受体放射自显影将用于确定 1)如果听觉操作延迟了敏感歌曲的关闭 学习期同样延长了NMDA受体的发育变化 密度或药理学，2)如果影响歌曲的荷尔蒙操作 研究改变了NMDA受体表达的发育特征，并且 3)如果成年金丝雀的发声可塑性的复发期是 伴随着NMDA受体密度或药理的变化。第二 一系列实验将进一步探索神经元 声带运动通路中的整合调节行为 可塑性。将在斑马雀身上使用逆行追踪来识别 细胞类型有助于刺激相关的数量之间的关系 歌曲相关神经元和所学歌曲材料的数量。另外， 蛋黄睾丸素水平的测量和操作将用于 评估孵化前激素水平的变化是否与个体有关 神经元数量或学习能力的差异。最后，成年孟加拉人 和斑马雀将使用胸腺嘧啶核苷放射自显影和 逆行示踪法确定HVC神经元的种类差异 相加可能解释了不同物种在声音恶化方面的差异。 震耳欲聋。许多行为(例如，语言习得，社交依恋， 印记)表现出它们对 环境刺激，这些研究将有助于确定神经机制 这会鼓励学习，限制独特的敏感时期。

DESCRIPTION (Adapted from applicant's abstract): Avian song learning is a powerful model for studying how experience influences neural and behavioral development. During song learning, birds memorize conspecific songs and use auditory feedback to shape their vocalizations to these stored models. This song learning often is restricted to species-specific sensitive periods, and this proposal is aimed at identifying neural events that encourage and constrain this learning. The studies focus upon two neural events that accompany song learning: developmental changes in the density and pharmacology of the N-methyl-D-aspartate (NMDA) glutamate receptor subtype, and a massive addition of new circuitry within the vocal motor pathway. NMDA receptors have been linked to many instances of experience-dependent neural plasticity and their activation is necessary for the memorization phase of song learning. Behavioral pharmacology and Golgi staining will be combined in zebra finches to determine whether NMDA receptor activation prompts the decline in dendritic spines that occurs in one song region during learning. Also, receptor autoradiography will be used to determine 1) if auditory manipulations that delay closure of the sensitive song learning period similarly extend developmental changes in NMDA receptor density or pharmacology, 2) if hormonal manipulations that affect song development alter the developmental profile of NMDA receptor expression, and 3) if recurring periods of vocal plasticity in adult canaries are accompanied by changes in NMDA receptor density or pharmacology. The second set of experiments will explore further the hypothesis that neuronal incorporation within the vocal motor pathway regulates behavioral plasticity. Retrograde tracing will be used in zebra finches to identify cell types contributing to a provocative correlation between the number of song-related neurons and the amount of song material learned. Also, measurements and manipulations of yolk testosterone levels will be used to assess if variations in prehatch hormone levels relate to individual differences in neuron number or learning capacity. Finally, adult Bengalese and zebra finches will be compared using thymidine autoradiography and retrograde tracing to determine if species differences in HVC neuron addition may account for species differences in vocal deterioration after deafening. Many behaviors (e.g., language acquisition, social attachment, imprinting) exhibit developmental changes in their sensitivity to environmental stimuli, and these studies will help define neural mechanisms that encourage learning and constrain periods of unique susceptibility.