[论文解读] Basic Neural Units of the Brain: Neurons, Synapses and Action Potential

Jiawei Zhang|arXiv (Cornell University)|May 30, 2019

Cellular transport and secretion参考文献 7被引用 37

一句话总结

本论文提供了对基本神经单位——神经元、突触和动作电位——的教程性概述，涵盖它们的结构、类型和信号传导机制。

ABSTRACT

As a follow-up tutorial article of [29], in this paper, we will introduce the basic compositional units of the human brain, which will further illustrate the cell-level bio-structure of the brain. On average, the human brain contains about 100 billion neurons and many more neuroglia which serve to support and protect the neurons. Each neuron may be connected to up to 10,000 other neurons, passing signals to each other via as many as 1,000 trillion synapses. In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another neuron or to the target effector cell. Such signals will be accumulated as the membrane potential of the neurons, and it will trigger and pass the signal pulse (i.e., action potential) to other neurons when the membrane potential is greater than a precisely defined threshold voltage. To be more specific, in this paper, we will talk about the neurons, synapses and the action potential concepts in detail. Many of the materials used in this paper are from wikipedia and several other neuroscience introductory articles, which will be properly cited in this paper. This is the second of the three tutorial articles about the brain (the other two are [29] and [28]). The readers are suggested to read the previous tutorial article [29] to get more background information about the brain structure and functions prior to reading this paper.

研究动机与目标

• 介绍大脑的细胞层级组成（神经元、突触和神经胶质细胞）及其在神经信号传递中的作用。
• 解释神经元的结构、分类（形态与功能）以及连接性。
• 描述突触结构、囊泡、神经递质，以及突触囊泡循环与再循环。
• 讨论膜电位、离子通道、泵以及动作电位的生成。

提出的方法

• 对来自入门资料和现有文献的基础神经科学概念进行梳理与综合。
• 对神经元形态（细胞体、树突、轴突、髓鞘、朗氏结节点）及支持性胶质细胞进行详细阐述。
• 对突触结构、化学突触与电突触，以及传递机制进行描述。
• 对突触囊泡循环进行分步叙述，包括定位、准备、融合和内吞。
• 讨论膜电位的维持、离子通道与动作潜在的生成。

实验结果

研究问题

• RQ1 神经元的核心结构成分是什么，它们如何相互作用来处理和传递信号？
• RQ2 突触如何将电信号转换为化学信号再转换回去？囊泡和神经递质在其中扮演什么角色？
• RQ3 神经元中动作电位的产生与传播的机制是什么？
• RQ4 胶质细胞如何促成神经元通信与可塑性？

主要发现

• 神经元由细胞体、树突和一个轴突组成，具有如轴突起、髓鞘和朗氏结节点等专门结构，影响兴奋性。
• 突触有化学型和电型，突触囊泡和神经递质介导跨越突触间隙的化学信号传递。
• 突触囊泡通过运输、装载、定位、准备、融合和内吞循环，实现快速的神经递质释放与循环。
• 膜电位由离子梯度与离子通道/泵产生，使得可变电位和全或无的动作电位得以传播信号。
• 胶质细胞数量丰富，且越来越被理解为主动参与脑信号传递和可塑性，而不仅仅是支持作用。
• 脑内信号传导过程涉及在亚秒级的时间尺度内，从电信号到化学信号再回到电信号的转换。