Functional Analyses of the Neural Circuits Underlying Vocal Production in Xenopus Laevis

大脑功能最显著的输出是行为。 然而，神经系统如何产生行为还没有得到很好的理解，这主要是因为行为背后的大多数神经通路都很复杂。 在这个研究项目中，非洲爪蛙的发声行为被用作模型，因为它们的发声神经通路简单而直接，并且可以使用PI实验室以前开发的技术来研究这些通路。 除了它们的简单性和可访问性之外，青蛙的发声途径提供了一个独特的机会来研究女性和男性大脑的功能差异;男性和女性青蛙在繁殖季节产生性别特异性的发声，并且将男性特异性激素注射到成年女性中，在13周内产生类似男性的发声。 在这项研究中，重点放在一组已知在通路运作中起关键作用的细胞上。 将使用各种实验技术来了解这些神经元在哪里，这些神经元如何发挥作用，以及它们如何对男性特异性激素做出反应。 这项研究的结果不仅将使我们了解两性的行为是如何产生的，而且还将使我们深入了解人类大脑如何产生有节奏的活动，如α波和γ波，其中许多已知是认知过程的基础，并且已知在疾病状态下被破坏。 神经科学中的一个根本性的重要问题是神经网络如何产生构成行为基础的运动程序。 虽然分析产生行为的完整神经网络是一项艰巨的任务，但非洲爪蟾发声网络的相对简单性与虚构准备（“盘子中的唱歌大脑”准备）的发展以及行为，电生理，解剖学和新开发的光遗传学技术的应用相结合，可以详细研究大脑的动态组织。 这项研究的结果不仅将在细胞水平上深入了解产生节奏的神经网络的结构、功能和可塑性，还将使我们了解反馈回路如何被设计成一个网络以产生稳定的节奏的逻辑。 节律性神经元活动不仅限于运动系统，而且在整个CNS中普遍存在，并被认为是感知和认知等重要功能的基础。 因此，了解生物物理原理，使用一个简单的神经网络的节奏产生有可能阐明神经元振荡的机制。 在技术层面上，光遗传学工具在体外对非洲爪蟾虚构制剂的成功应用填补了在遗传与非遗传模式生物体上进行的研究工作之间的重要空白。 有许多非遗传模式生物提出了独特的问题。 在非模式生物中表达基因编码工具的能力代表了比较神经科学领域的革命性变化。

The most salient output of brain function is behavior. However, how the nervous system produces behavior is not well understood, largely because most of the neural pathways underlying behavior are complicated. In this research project, vocal behavior of African clawed frogs is used as a model because their vocal neural pathways are simple and straight forward, and the pathways in action can be studied using techniques that were previously developed in the PI's laboratory. In addition to their simplicity and accessibility, the frog vocal pathways provide a unique opportunity to study how female and male brains function differently; male and female frogs produce sex-specific vocalizations during the breeding season, and the injection of male-specific hormones into an adult female results in male-like vocalizations within thirteen weeks. In this study, the focus is placed on one group of cells that are known to play a critical role in the operation of the pathways. A variety of experimental techniques will be used to understand where these neurons are, how these neurons function, and how they respond to male-specific hormones. The results of the study will not only provide us with the understanding of how behaviors are generated in the two sexes, but also provide us with an insight into how human brains generates rhythmic activity such as alpha and gamma waves, many of which are known to underlie cognitive processes, and known to be disrupted in diseased states. A fundamentally important question in neuroscience is how neural networks function to generate motor programs that underlie behavior. Although analyses of a complete neural network that generates behavior is a formidable task, the relative simplicity of the Xenopus vocal network combined with the development of the fictive preparation (a "singing brain in a dish" preparation) and the application of behavioral, electrophysiological, anatomical, and newly developed optogenetic techniques allows detailed investigation of the dynamic organization of brain in action. The results of the proposed study will not only provide insight into the structure, function, and plasticity of the rhythm-generating neural network at the cellular levels, but also allow us to understand the logic of how a feedback loop should be engineered into a network to generate stable rhythms. Rhythmic neuronal activity is not limited to motor systems, but is prevalent across the entire CNS and is considered to underlie important functions such as perception and cognition. Thus, understanding the biophysical principles that govern rhythm generation using a simple neural network has a potential to elucidate mechanisms underlying neuronal oscillations in general. On a technical level, successful application of optogenetic tools to the Xenopus fictive preparation in vitro fills an important gap between research efforts conducted on genetic vs non-genetic model organisms. There are many non-genetic model organisms that present unique questions. The ability to express genetically encoded tools in non-model organisms represents a revolutionary change in the field of comparative neuroscience.