Optical Imaging of Information Processing in CNS Axons

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，并在直径约为一微米的纤维中传播，称为轴突。轴突的小尺寸使得传统的记录方法无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，在时间和空间上以高分辨率测量整个神经元的膜电位变化。为了更好地理解神经元是如何处理和交流信息的，我将使用这种强大的新技术来成像整个小脑浦肯野神经元轴突轴突单动作电位的启动和传播。在Specific Aim 1中，我将直接测量动作电位起始的位置。这些信息是我们理解神经元如何对输入做出反应的基础。在具体目标2中，我将研究动作电位是否在整个轴突乔木中忠实地传递。早期的理论和实验表明，相互连接的神经元之间的信息传递是随机的，并且通过高度分支的轴突传递动作电位的失败被假设为一种机制。我用VSD成像对动作电位传递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，我将研究神经元输入的近期历史如何影响动作电位的形状和传递。先前的实验表明，神经元最近的输入会影响它与邻近细胞的沟通方式。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轴突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讯中所起的基本作用的理解，并将为轴突功能异常变化引起的神经系统综合征的发生和进展提供见解。

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.