Optical Imaging of Information Processing in CNS Axons

描述（由申请人提供）： 神经元通过电脉冲进行交流，这种电脉冲被称为动作电位，持续时间不到千分之一秒，并在直径约为1微米的纤维（称为轴突）中传播。轴突的小尺寸阻碍了用传统记录方法直接表征动作电位。我将利用单细胞电压敏感染料（VSD）成像的最新进展，以高分辨率的时间和空间测量整个神经元的膜电位变化。为了更好地了解神经元如何处理和交流信息，我将使用这种强大的新技术来成像小脑浦肯野神经元轴突的单个动作电位的启动和传播。在具体目标1中，我将直接测量动作电位起始部位。这些信息对于我们理解神经元如何响应其输入至关重要。在具体目标2中，我将研究动作电位是否忠实地在整个轴突乔木中传播。早期的理论和实验已经表明，连接的神经元之间的信息传输是随机的，并且已经假设通过高度分支的轴突的动作电位传输失败是一种机制。我对VSD成像的动作电位传输的直接观察将显示这些故障发生的位置和频率。在具体目标3中，我将研究神经元最近的输入历史如何影响动作电位的形状和传输。以前的实验表明，最近输入到神经元的信息会影响它与相邻细胞的通信方式。我将使用VSD成像来观察最近的输入历史如何影响整个轴突乔木的动作电位形状和传输保真度。这些实验将增加我们对轴突在神经元通信中所起的基本作用的理解，并应提供对轴突功能异常变化引起的神经综合征的发展和进展的见解。 公共卫生相关性： 轴突的正常功能是神经元的主要输出结构，是健康、功能性大脑和神经系统的关键组成部分。我们的研究将使用最新的先进技术来阐明正常轴突生理学的重要基本特性。我们的数据将为神经系统症状和综合征（如多发性硬化症和周围神经病）如何由轴突功能的异常变化引起提供新的见解。

DESCRIPTION (provided by applicant): Neurons communicate via electrical impulses, called action potentials, that last for less than one thousandth of a second and travel in fibers, called axons, approximately one micrometer in diameter. The small size of axons has prevented direct characterization of action potentials with traditional recording methods. I will utilize recent advancements in single cell voltage-sensitive dye (VSD) imaging to measure changes in membrane electrical potential throughout the neuron with high resolution in time and space. To obtain a better understanding of how neurons process and communicate information, I will use this powerful new technique to image initiation and propagation of single action potentials throughout the axonal arbor of cerebellar Purkinje neurons. In Specific Aim 1, I will directly measure the site of action potential initiation. This information is fundamental to our understanding of how neurons respond to their inputs. In Specific Aim 2, I will investigate whether action potentials travel faithfully throughout the axonal arbor. Earlier theory and experiments have shown that the transmission of information between connected neurons is stochastic, and failures in action potential transmission through highly branched axons have been hypothesized as a mechanism. My direct observations of action potential transmission with VSD imaging will show where and how often these failures occur. In Specific Aim 3, I will investigate how the recent history of input to a neuron influences action potential shape and transmission. Previous experiments have shown that recent inputs to a neuron can influence how it communicates with neighboring cells. I will use VSD imaging to observe how recent history of inputs influences action potential shape and transmission fidelity throughout the axonal arbor. These experiments will increase our understanding of the fundamental role played by axons in neuronal communication and should provide insights into the development and progression of neurological syndromes that arise from abnormal changes in axonal function. PUBLIC HEALTH RELEVANCE: The proper function of axons, the primary output structures of neurons, is a critical component of a healthy, functional brain and nervous system. Our study will use recently advanced technologies to elucidate important basic properties of normal axonal physiology. Our data will provide new insights into how neurological symptoms and syndromes, such as multiple sclerosis and peripheral neuropathies, may arise from abnormal changes in axonal function.