Optical Imaging of Information Processing in CNS Axons

神经元通过称为动作电位的电脉冲进行交流，这种脉冲持续时间不到千分之一秒，并以直径约一微米的称为轴突的纤维传播。轴突的小尺寸阻碍了传统记录方法对动作电位的直接表征。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，我将使用这项强大的新技术来成像单个动作电位的启动和传播，穿过小脑浦肯野神经元的轴突。在具体目标1中，我将直接测量动作电位的起始点。这些信息是我们理解神经元如何对其输入做出反应的基础。在具体目标2中，我将调查动作电位是否忠实地贯穿轴突。早期的理论和实验表明，连接的神经元之间的信息传输是随机的，动作电位通过高度分支的轴突的传输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地点和频率。在具体目标3中，我将调查最近对神经元的输入历史如何影响动作电位的形状和传递。先前的实验表明，神经元最近的输入可以影响它与邻近细胞的通讯方式。我将使用VSD成像来观察最近的输入历史如何影响动作电位的形状和整个轴突的传输保真度。这些实验将增加我们对轴突在神经元交流中所起的基础作用的理解，并应该为轴突功能异常变化引起的神经综合征的发展和进展提供见解。

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.