Mechanisms of respiratory-related rhythmic motor activity and plasticity in the avian brain stem

描述(由申请人提供)：我们研究团队的长期目标是了解控制维持生命的自主呼吸模式的脑干运动回路是如何发展、成熟和维持有节奏的神经活动的。确定这些电路如何对异常环境和压力做出反应也是相关的。本项目拟使用一种新的实验模型系统来研究早期发育过程中与呼吸相关的中枢模式产生器(CPGs)在独立斑雀脑干中的位置(S)、突触生理学和可塑性。鸟类胚胎模型对于实验操作来说是唯一容易处理的，并提供了在整个产前发育过程中无与伦比的中枢神经网络通道。我们将使用解剖学技术、神经细胞活动和药理学来测试我们的假设，以了解正常的呼吸行为和与呼吸相关的神经病理，在这些病理中，控制正常节奏和运动模式的脑干结构的修改或丢失可能会导致新生儿和成年人的发病率和死亡率增加。重要的是，这项提案的资金将向学生介绍爱达荷州立大学(ISU)基于生物医学的研究，使用实际操作的实验室经验，并专注于各种专业和科学实践中的个人培训。我们试图解决与发育神经生物学和呼吸控制领域相关的三个关键方面：1.空间分离的与呼吸相关的脑干CPG的鉴定。目的1研究鸟类副疑核(Pam)和疑后核(Ram)在自主呼吸节律神经发生中的作用。从历史上看，体外研究主要集中在吸气阶段。然而，呼吸周期包括吸气和呼气。由于鸟类使用主动吸气和主动呼气，即使在休息时，我们假设鸟类胚胎在内部孵化阶段(即开始持续呼吸空气时)通过两个独立但耦合的CPG产生呼吸节律，类似于需要高水平呼吸驱动的锻炼人类的情况。2.鸟类脑干爆发的发生和模式形成机制。目标2将检验这一假设，即鸟类与呼吸相关的CPG行为严重依赖抑制性突触输入，类似于许多 基于网络的机车CPG电路。具体地说，我们假设自发节律将严重依赖于氯介导的神经传递作为控制呼吸模式的占空比的机制。作为替代假设，我们将检验内源性起搏机制在维持和形成与呼吸相关的CPG输出中的作用。呼吸相关脑干的动态平衡/发育可塑性机制。目的3将测试持续的胚胎对节律性电活动的操纵以及对特定神经递质的操纵是否会改变CPG行为的发育表达以及支持呼吸的神经递质系统的表型。

DESCRIPTION (provided by applicant): The long term goal of our research team is to understand how brain stem motor circuits that control life sustaining autonomous breathing patterns develop, mature and maintain rhythmic neural activity. It is also relevant to determine how these circuits respond to abnormal environments and stress. This project proposes to use a new experimental model system to explore the location(s), synaptic physiology, and plasticity of breathing-related central pattern generators (CPGs) in the isolated Zebra Finch brain stem during early development. The avian embryonic model is uniquely tractable for experimental manipulation and provides unparalleled access to central neuronal networks throughout prenatal development. We will use anatomical techniques, nerve cell activities, and pharmacology to test our hypotheses in the context of understanding normal breathing behaviors and breathing-related neuropathologies in which the modification or loss of brain stem structures that control normal rhythm and motor patterns can lead to increased morbidity and mortality in neonates and adults. Importantly, funds from this proposal will introduce students to Biomedically-based research at Idaho State University (ISU) using hands-on lab experiences and focused individual training in a variety of professional and scientific practices. We seek to address three key aspects associated with the field of developmental neurobiology and the control of breathing: 1. Identification of spatially separate respiratory-related brain stem CPGs. Aim 1 will test the role of the avian nucleus paraambiguus (PAm) and the retroambiguus (RAm) in the neurogenesis of automatic breathing rhythms. Historically, in vitro studies have focused on the inspiratory phase. Yet, the breathing cycle involves both inspiration and expiration. Since birds employ active inspiration and active expiration, even at rest, we hypothesize that avian embryos at the internal hatching stage (i.e., when continuous air-breathing begins) generate breathing rhythms with two independent yet coupled CPGs, similar to the situation in exercising humans when high levels of ventilatory drive is necessary. 2. Mechanisms of burst generation and pattern formation in the avian brain stem. Aim 2 will test the hypothesis that respiratory-related CPG behavior in birds is critically dependent on inhibitory synaptic input, similar to many network-based locomotor CPG circuits. Specifically, we hypothesize spontaneous rhythms will be critically dependent on chloride-mediated neurotransmission as a mechanism to control duty cycles for breathing pattern. As an alternate hypothesis, we will test the role of endogenous pacemaker mechanisms in the maintenance and shape of respiratory-related CPG output.3. Mechanisms of homeostatic/developmental plasticity in the breathing-related brain stem. Aim 3 will test how persistent embryonic manipulations of rhythmic electrical activity with and without manipulations of specific neurotransmitters may alter the developmental expression of CPG behavior as well as the phenotype of neurotransmitter systems that support breathing.