Temporal Dynamics of Neural Plasticity During Auditory Discrimination Learning

描述(申请人提供)：鸣禽，如八哥，为语言发展和听觉识别和学习提供了一个极好的模型。行为数据表明，八哥依赖于对特定的SONG元素的识别来识别它们的邻居，细胞外电生理和IEG(即刻早期基因)研究表明，高水平听觉区域的神经元对这些SONG元素有选择性的反应。先前对八哥和哺乳动物的研究表明，感觉任务的学习调节初级和高级感觉区域神经元的放电特性。八哥很容易适应操控训练环境，表现出对与野外歌曲识别行为有关的复杂听觉“对象”的快速学习。该应用程序旨在确定听觉神经元对训练刺激的反应在整个学习过程中如何演变，同时测试听觉记忆巩固和干扰理论。为了在监测整个学习过程中整个区域的变化的同时，检查神经表征在细微的时间和空间细节上的变化，将使用慢性行为和清醒受限的多部位单单位电生理技术。这将允许观察鸟在训练任务中进行个别试验时单个单位神经元的反应特性的变化，以及评估在几天的过程中发生的大量神经元的总神经反应强度的变化。我们将研究听觉记忆是如何形成的，以及当获得新的记忆时，这些模式是如何改变的。对个别歌曲“基调”的共鸣强度的短暂的、广泛分布的变化将预示着最初的习得阶段。小部分选择性反应神经元数量或强度的长期变化将与记忆维持有关。这些实验有可能阐明听觉记忆是如何形成的，以及如何从不稳定状态转变为长期记忆中的固定状态。我们记忆和快速提取单词的能力是人类认知的一个基本元素，对言语和语言的语义有贡献。各种疾病可以扰乱这一过程，导致毁灭性的损害，但治疗受到阻碍，因为人们对高级听觉处理的基本神经元底物知之甚少。在这里，我们对一种新的动物系统进行应用研究，该系统很有希望深入了解听觉记忆是如何形成和维持的。

DESCRIPTION (provided by applicant): Songbirds such as starlings provide an excellent model for speech development and auditory recognition and learning. Behavioral data indicates that starlings rely on recognition of specific elements of song to identify their neighbors and extracellular electrophysiological and IEG (immediate early gene) studies have revealed that neurons in high-level auditory areas respond selectively to these song elements. Previous studies in starlings, as well as mammals indicate that learning of a sensory task modulates the firing properties of neurons in primary and high-level sensory areas. Starlings readily adapt to an operant training environment, exhibiting rapidly learning of complex auditory "objects" related to song recognition behavior in the wild. The application aims to determine how the response of auditory neurons to training stimuli evolves over the full course of learning while testing theories on auditory memory consolidation and interference. In order to examine changes in neural representations in fine temporal and spatial detail while monitoring the changes within the entire region over the full course of learning, both chronic behaving and awake restrained multisite single unit electrophysiological techniques will be used. This will permit observation of modifications in the response properties of single unit neurons as the bird performs individual trials in the training task, as well as assessment of shifts in the aggregate neural response strength of large populations of neurons occurring over the course of days. We will examine both how auditory memories are laid down and how these patterns change when new memories are acquired. Transitory, broadly distributed changes in strength of resposne to individual song "motifs" will be indicative of an initial acquisition phase. Longer- term changes in number or strength of small set of selectively responding neurons will be related to memory maintenance. These experiments have the potential to shed light on how auditory memories are formed and pass from a labile state to become fixed in long-term memory. Our ability to memorize and rapidly retrieve words is a fundamental element of human cognition, contributing to semantics in speech and language. A variety of illnesses can disrupt this process leading to devastating impairment, yet treatment is hindered because the basic neuronal substrates for high-level auditory processing are poorly understood. Here we application research on a novel animal system that has great promise to give insights into how auditory memories are formed and maintained.