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== Nervous system ==
== Nervous system神经系统 ==
[[File:Anatomy of a Neuron with Synapse.png|thumb|upright=1.15|Schematic of an anatomically accurate single pyramidal neuron, the primary excitatory neuron of cerebral cortex, with a synaptic connection from an incoming axon onto a dendritic spine.]]
[[File:Anatomy of a Neuron with Synapse.png|thumb|upright=1.15|Schematic of an anatomically accurate single pyramidal neuron, the primary excitatory neuron of cerebral cortex, with a synaptic connection from an incoming axon onto a dendritic spine.]]
轴突可以捆绑成束，组成周围神经系统的神经（就像电线股组成的电缆）。中枢神经系统中的轴突束被称为束。
轴突可以捆绑成束，组成周围神经系统的神经（就像电线股组成的电缆）。中枢神经系统中的轴突束被称为束。
== Anatomy and histology ==
== Anatomy and histology解剖学和组织学 ==
[[File:Components of neuron.jpg|thumb|upright=1.8|Diagram of the components of a neuron]]
[[File:Components of neuron.jpg|thumb|upright=1.8|Diagram of the components of a neuron]]
*轴突终端位于轴突离胞体最远的一端，包含突触。突触结是专门的结构，神经递质化学物质在此释放，与目标神经元进行交流。除了轴突末端的突触结外，神经元还可能有沿轴突长度方向分布的 "中途结"。
*轴突终端位于轴突离胞体最远的一端，包含突触。突触结是专门的结构，神经递质化学物质在此释放，与目标神经元进行交流。除了轴突末端的突触结外，神经元还可能有沿轴突长度方向分布的 "中途结"。
[[File:Neuron Cell Body.png|thumb|Neuron cell body]]
[[File:Neuron Cell Body.png|thumb|Neuron cell body神经元细胞体]]
The accepted view of the neuron attributes dedicated functions to its various anatomical components; however, dendrites and axons often act in ways contrary to their so-called main function.<ref>{{Cite web |date=2021-01-14 |title=16.7: Nervous System |url=https://bio.libretexts.org/Courses/Lumen_Learning/Book%3A_Fundamentals_of_Biology_I_(Lumen)/16%3A_Module_13%3A_Overview_of_Body_Systems/16.7%3A_Nervous_System |access-date=2022-02-28 |website=Biology LibreTexts |language=en}}</ref>
The accepted view of the neuron attributes dedicated functions to its various anatomical components; however, dendrites and axons often act in ways contrary to their so-called main function.<ref>{{Cite web |date=2021-01-14 |title=16.7: Nervous System |url=https://bio.libretexts.org/Courses/Lumen_Learning/Book%3A_Fundamentals_of_Biology_I_(Lumen)/16%3A_Module_13%3A_Overview_of_Body_Systems/16.7%3A_Nervous_System |access-date=2022-02-28 |website=Biology LibreTexts |language=en}}</ref>
公认的神经元观点将专门的功能归于其各种解剖成分；然而，树突和轴突的作用方式往往与它们所谓的主要功能相反。
公认的神经元观点将专门的功能归于其各种解剖成分；然而，树突和轴突的作用方式往往与它们所谓的主要功能相反。
[[File:Complete neuron cell diagram en.svg|thumb|right|Diagram of a typical myelinated vertebrate motor neuron]]
[[File:Complete neuron cell diagram en.svg|thumb|right|Diagram of a typical myelinated vertebrate motor neuron典型的有髓的脊椎动物运动神经元示意图]]
[[File:BN1 Neurology.webm|thumb|Neurology Video]]
[[File:BN1 Neurology.webm|thumb|Neurology Video神经病学视频]]
Axons and dendrites in the central nervous system are typically only about one micrometer thick, while some in the peripheral nervous system are much thicker. The soma is usually about 10–25 micrometers in diameter and often is not much larger than the cell nucleus it contains. The longest axon of a human [[motor neuron]] can be over a meter long, reaching from the base of the spine to the toes.
Axons and dendrites in the central nervous system are typically only about one micrometer thick, while some in the peripheral nervous system are much thicker. The soma is usually about 10–25 micrometers in diameter and often is not much larger than the cell nucleus it contains. The longest axon of a human [[motor neuron]] can be over a meter long, reaching from the base of the spine to the toes.
完全分化的神经元是永久性的有丝分裂后的细胞 ，然而，存在于成人大脑中的干细胞可以在有机体的整个生命过程中再生出功能性神经元（见神经元的生成）。星形胶质细胞是星形的胶质细胞。它们已经被观察到可以凭借其类干细胞的多能性特征而变成神经元。
完全分化的神经元是永久性的有丝分裂后的细胞 ，然而，存在于成人大脑中的干细胞可以在有机体的整个生命过程中再生出功能性神经元（见神经元的生成）。星形胶质细胞是星形的胶质细胞。它们已经被观察到可以凭借其类干细胞的多能性特征而变成神经元。
===Membrane===
===Membrane膜结构===
{{unreferenced section|date=December 2020}}
{{unreferenced section|date=December 2020}}
Like all animal cells, the cell body of every neuron is enclosed by a [[plasma membrane]], a bilayer of [[lipid]] molecules with many types of protein structures embedded in it. A lipid bilayer is a powerful electrical [[Insulator (electricity)|insulator]], but in neurons, many of the protein structures embedded in the membrane are electrically active. These include ion channels that permit electrically charged ions to flow across the membrane and ion pumps that chemically transport ions from one side of the membrane to the other. Most ion channels are permeable only to specific types of ions. Some ion channels are [[voltage-gated ion channel|voltage gated]], meaning that they can be switched between open and closed states by altering the voltage difference across the membrane. Others are chemically gated, meaning that they can be switched between open and closed states by interactions with chemicals that diffuse through the extracellular fluid. The [[ion]] materials include [[sodium]], [[potassium]], [[chloride]], and [[calcium]]. The interactions between ion channels and ion pumps produce a voltage difference across the membrane, typically a bit less than 1/10 of a volt at baseline. This voltage has two functions: first, it provides a power source for an assortment of voltage-dependent protein machinery that is embedded in the membrane; second, it provides a basis for electrical signal transmission between different parts of the membrane.
Like all animal cells, the cell body of every neuron is enclosed by a [[plasma membrane]], a bilayer of [[lipid]] molecules with many types of protein structures embedded in it. A lipid bilayer is a powerful electrical [[Insulator (electricity)|insulator]], but in neurons, many of the protein structures embedded in the membrane are electrically active. These include ion channels that permit electrically charged ions to flow across the membrane and ion pumps that chemically transport ions from one side of the membrane to the other. Most ion channels are permeable only to specific types of ions. Some ion channels are [[voltage-gated ion channel|voltage gated]], meaning that they can be switched between open and closed states by altering the voltage difference across the membrane. Others are chemically gated, meaning that they can be switched between open and closed states by interactions with chemicals that diffuse through the extracellular fluid. The [[ion]] materials include [[sodium]], [[potassium]], [[chloride]], and [[calcium]]. The interactions between ion channels and ion pumps produce a voltage difference across the membrane, typically a bit less than 1/10 of a volt at baseline. This voltage has two functions: first, it provides a power source for an assortment of voltage-dependent protein machinery that is embedded in the membrane; second, it provides a basis for electrical signal transmission between different parts of the membrane.
像所有的动物细胞一样，每个神经元的细胞体都被一个质膜所包围，质膜是由脂质分子组成的双层膜，其中嵌入了许多类型的蛋白质结构。脂质双层是一个强大的电绝缘体，但在神经元中，嵌入膜中的许多蛋白质结构是电活性的。这些结构包括允许带电离子流过膜的离子通道和以化学方式将离子从膜的一侧输送到另一侧的离子泵。大多数离子通道只对特定类型的离子有渗透性。一些离子通道是电压门控的，这意味着它们可以通过改变膜上的电压差在开放和关闭状态之间进行切换。其他的是化学门控，意味着它们可以通过与扩散在细胞外液中的化学物质的相互作用在开放和关闭状态之间切换。离子材料包括钠、钾、氯和钙。离子通道和离子泵之间的相互作用在膜上产生一个电压差，通常在基线上小于1/10伏。这个电压有两个功能：首先，它为嵌入膜中的各种电压依赖性蛋白机械提供了动力源；其次，它为膜的不同部分之间的电信号传输提供了一个基础。
像所有的动物细胞一样，每个神经元的细胞体都被一个质膜所包围，质膜是由脂质分子组成的双层膜，其中嵌入了许多类型的蛋白质结构。脂质双层是一个强大的电绝缘体，但在神经元中，嵌入膜中的许多蛋白质结构是电活性的。这些结构包括允许带电离子流过膜的离子通道和以化学方式将离子从膜的一侧输送到另一侧的离子泵。大多数离子通道只对特定类型的离子有渗透性。一些离子通道是电压门控的，这意味着它们可以通过改变膜上的电压差在开放和关闭状态之间进行切换。其他的是化学门控，意味着它们可以通过与扩散在细胞外液中的化学物质的相互作用在开放和关闭状态之间切换。离子材料包括钠、钾、氯和钙。离子通道和离子泵之间的相互作用在膜上产生一个电压差，通常在基线上小于1/10伏。这个电压有两个功能：首先，它为嵌入膜中的各种电压依赖性蛋白机械提供了动力源；其次，它为膜的不同部分之间的电信号传输提供了一个基础。
===Histology and internal structure===
===Histology and internal structure组织学和内部结构===
[[File:Gyrus Dentatus 40x.jpg|thumb|250px|Golgi-stained neurons in human hippocampal tissue]]
[[File:Gyrus Dentatus 40x.jpg|thumb|250px|Golgi-stained neurons in human hippocampal tissue高尔基染色神经元在人海马组织]]
[[Image:SUM 110913 Cort Neurons 2.5d in vitro 488 Phalloidin no perm 4 cmle-2.png|thumb|300px|Actin filaments in a mouse cortical neuron in culture]]
[[Image:SUM 110913 Cort Neurons 2.5d in vitro 488 Phalloidin no perm 4 cmle-2.png|thumb|300px|Actin filaments in a mouse cortical neuron in culture培养中的小鼠皮质神经元中的肌动蛋白丝]]
Numerous microscopic clumps called [[Nissl body|Nissl bodies]] (or Nissl substance) are seen when nerve cell bodies are stained with a basophilic ("base-loving") dye. These structures consist of [[Endoplasmic reticulum#Rough endoplasmic reticulum|rough endoplasmic reticulum]] and associated [[ribosomal RNA]]. Named after German psychiatrist and neuropathologist [[Franz Nissl]] (1860–1919), they are involved in protein synthesis and their prominence can be explained by the fact that nerve cells are very metabolically active. Basophilic dyes such as [[aniline]] or (weakly) [[haematoxylin]]<ref>{{cite book|title=State Hospitals Bulletin|url={{google books |plainurl=y |id=Wp8CAAAAYAAJ|page=378}}|year=1897|publisher=State Commission in Lunacy.|page=378}}</ref> highlight negatively charged components, and so bind to the phosphate backbone of the ribosomal RNA.
Numerous microscopic clumps called [[Nissl body|Nissl bodies]] (or Nissl substance) are seen when nerve cell bodies are stained with a basophilic ("base-loving") dye. These structures consist of [[Endoplasmic reticulum#Rough endoplasmic reticulum|rough endoplasmic reticulum]] and associated [[ribosomal RNA]]. Named after German psychiatrist and neuropathologist [[Franz Nissl]] (1860–1919), they are involved in protein synthesis and their prominence can be explained by the fact that nerve cells are very metabolically active. Basophilic dyes such as [[aniline]] or (weakly) [[haematoxylin]]<ref>{{cite book|title=State Hospitals Bulletin|url={{google books |plainurl=y |id=Wp8CAAAAYAAJ|page=378}}|year=1897|publisher=State Commission in Lunacy.|page=378}}</ref> highlight negatively charged components, and so bind to the phosphate backbone of the ribosomal RNA.
轴突和树突之间存在着不同的内部结构特征。典型的轴突几乎不含核糖体，除了在初始段有一些。树突含有颗粒状的内质网或核糖体，随着与细胞体距离的增加，其数量逐渐减少。
轴突和树突之间存在着不同的内部结构特征。典型的轴突几乎不含核糖体，除了在初始段有一些。树突含有颗粒状的内质网或核糖体，随着与细胞体距离的增加，其数量逐渐减少。
==Classification==
==Classification分类==
[[File:GFPneuron.png|thumb|250px|right|Image of pyramidal neurons in mouse [[cerebral cortex]] expressing [[green fluorescent protein]]. The red staining indicates [[GABA]]ergic interneurons.<ref>{{cite journal | vauthors = Lee WC, Huang H, Feng G, Sanes JR, Brown EN, So PT, Nedivi E | title = Dynamic remodeling of dendritic arbors in GABAergic interneurons of adult visual cortex | journal = PLOS Biology | volume = 4 | issue = 2 | pages = e29 | date = February 2006 | pmid = 16366735 | pmc = 1318477 | doi = 10.1371/journal.pbio.0040029 |doi-access=free }}</ref>]]
[[File:GFPneuron.png|thumb|250px|right|Image of pyramidal neurons in mouse [[cerebral cortex]] expressing [[green fluorescent protein]]. The red staining indicates [[GABA]]ergic interneurons.<ref>{{cite journal | vauthors = Lee WC, Huang H, Feng G, Sanes JR, Brown EN, So PT, Nedivi E | title = Dynamic remodeling of dendritic arbors in GABAergic interneurons of adult visual cortex | journal = PLOS Biology | volume = 4 | issue = 2 | pages = e29 | date = February 2006 | pmid = 16366735 | pmc = 1318477 | doi = 10.1371/journal.pbio.0040029 |doi-access=free }}</ref>]]
神经元的形状和大小各不相同，可按其形态和功能进行分类。 解剖学家卡米洛-高尔基将神经元分为两类；I型有长轴，用于长距离移动信号；II型有短轴，常与树突相混淆。I型细胞可按胞体的位置进一步分类。以脊髓运动神经元为代表的I型神经元的基本形态包括一个称为胞体的细胞体和一个由髓鞘覆盖的细长轴突。树突树环绕着细胞体，接收来自其他神经元的信号。轴突的末端有分支的轴突终端，将神经递质释放到终端和下一个神经元树突之间的间隙中，称为突触间隙。
神经元的形状和大小各不相同，可按其形态和功能进行分类。 解剖学家卡米洛-高尔基将神经元分为两类；I型有长轴，用于长距离移动信号；II型有短轴，常与树突相混淆。I型细胞可按胞体的位置进一步分类。以脊髓运动神经元为代表的I型神经元的基本形态包括一个称为胞体的细胞体和一个由髓鞘覆盖的细长轴突。树突树环绕着细胞体，接收来自其他神经元的信号。轴突的末端有分支的轴突终端，将神经递质释放到终端和下一个神经元树突之间的间隙中，称为突触间隙。
===Structural classification===
===Structural classification结构分类===
====Polarity====
====Polarity极性====
[[File:Neurons uni bi multi pseudouni.svg|thumb|Different kinds of neurons:<br />1 [[Unipolar neuron]]<br />2 [[Bipolar neuron]]<br />3 [[Multipolar neuron]]<br />4 [[Pseudounipolar neuron]] ]]
[[File:Neurons uni bi multi pseudouni.svg|thumb|Different kinds of neurons不同种类的神经元:<br />1 [[Unipolar neuron单极神经元]]<br />2 [[Bipolar neuron双极神经元]]<br />3 [[Multipolar neuron多极神经元]]<br />4 [[Pseudounipolar neuron伪单极神经元]] ]]
Most neurons can be anatomically characterized as:
Most neurons can be anatomically characterized as:
* 假单极神经元：1个原生质过程，然后既是轴突又是树突。
* 假单极神经元：1个原生质过程，然后既是轴突又是树突。
====Other====
====Other其他====
Some unique neuronal types can be identified according to their location in the nervous system and distinct shape. Some examples are:
Some unique neuronal types can be identified according to their location in the nervous system and distinct shape. Some examples are:
*[[Anterior horn (spinal cord)|Anterior horn]] cells, [[motoneurons]] located in the spinal cord
*[[Anterior horn (spinal cord)|Anterior horn]] cells, [[motoneurons]] located in the spinal cord
*[[Spindle cell]]s, interneurons that connect widely separated areas of the brain
*[[Spindle cell]]s, interneurons that connect widely separated areas of the brain
*篮状细胞，在目标细胞的胞体周围形成密集的终端丛，发现于大脑皮层和小脑的中间神经元。
*篮状细胞，在目标细胞的胞体周围形成密集的终端丛，发现于大脑皮层和小脑的中间神经元。
*纺锤体细胞的运动神经元、连接大脑广泛分离区域的中间神经元
*纺锤体细胞的运动神经元、连接大脑广泛分离区域的中间神经元
===Functional classification===
===Functional classification功能分类===
====Direction====
====Direction方向====
*[[Afferent neuron]]s convey information from tissues and organs into the central nervous system and are also called [[sensory neurons]].
*[[Afferent neuron]]s convey information from tissues and organs into the central nervous system and are also called [[sensory neurons]].
传入和传出也泛指分别为大脑带来信息或从大脑发出信息的神经元。
传入和传出也泛指分别为大脑带来信息或从大脑发出信息的神经元。
====Action on other neurons====
====Action on other neurons对其他神经元的影响====
A neuron affects other neurons by releasing a neurotransmitter that binds to [[receptor (biochemistry)|chemical receptor]]s. The effect upon the postsynaptic neuron is determined by the type of receptor that is activated, not by the presynaptic neuron or by the neurotransmitter. A neurotransmitter can be thought of as a key, and a receptor as a lock: the same neurotransmitter can activate multiple types of receptors. Receptors can be classified broadly as ''excitatory'' (causing an increase in firing rate), ''inhibitory'' (causing a decrease in firing rate), or ''modulatory'' (causing long-lasting effects not directly related to firing rate).
A neuron affects other neurons by releasing a neurotransmitter that binds to [[receptor (biochemistry)|chemical receptor]]s. The effect upon the postsynaptic neuron is determined by the type of receptor that is activated, not by the presynaptic neuron or by the neurotransmitter. A neurotransmitter can be thought of as a key, and a receptor as a lock: the same neurotransmitter can activate multiple types of receptors. Receptors can be classified broadly as ''excitatory'' (causing an increase in firing rate), ''inhibitory'' (causing a decrease in firing rate), or ''modulatory'' (causing long-lasting effects not directly related to firing rate).
The distinction between excitatory and inhibitory neurotransmitters is not absolute. Rather, it depends on the class of chemical receptors present on the postsynaptic neuron. In principle, a single neuron, releasing a single neurotransmitter, can have excitatory effects on some targets, inhibitory effects on others, and modulatory effects on others still. For example, [[photoreceptor cell]]s in the retina constantly release the neurotransmitter glutamate in the absence of light. So-called OFF [[retinal bipolar cells|bipolar cells]] are, like most neurons, excited by the released glutamate. However, neighboring target neurons called ON bipolar cells are instead inhibited by glutamate, because they lack typical [[ionotropic receptor|ionotropic]] [[glutamate receptors]] and instead express a class of inhibitory [[metabotropic receptor|metabotropic]] glutamate receptors.<ref>{{cite journal | vauthors = Gerber U | title = Metabotropic glutamate receptors in vertebrate retina | journal = Documenta Ophthalmologica. Advances in Ophthalmology | volume = 106 | issue = 1 | pages = 83–7 | date = January 2003 | pmid = 12675489 | doi = 10.1023/A:1022477203420 | s2cid = 22296630 }}</ref> When light is present, the photoreceptors cease releasing glutamate, which relieves the ON bipolar cells from inhibition, activating them; this simultaneously removes the excitation from the OFF bipolar cells, silencing them.
The distinction between excitatory and inhibitory neurotransmitters is not absolute. Rather, it depends on the class of chemical receptors present on the postsynaptic neuron. In principle, a single neuron, releasing a single neurotransmitter, can have excitatory effects on some targets, inhibitory effects on others, and modulatory effects on others still. For example, [[photoreceptor cell]]s in the retina constantly release the neurotransmitter glutamate in the absence of light. So-called OFF [[retinal bipolar cells|bipolar cells]] are, like most neurons, excited by the released glutamate. However, neighboring target neurons called ON bipolar cells are instead inhibited by glutamate, because they lack typical [[ionotropic receptor|ionotropic]] [[glutamate receptors]] and instead express a class of inhibitory [[metabotropic receptor|metabotropic]] glutamate receptors.<ref>{{cite journal | vauthors = Gerber U | title = Metabotropic glutamate receptors in vertebrate retina | journal = Documenta Ophthalmologica. Advances in Ophthalmology | volume = 106 | issue = 1 | pages = 83–7 | date = January 2003 | pmid = 12675489 | doi = 10.1023/A:1022477203420 | s2cid = 22296630 }}</ref> When light is present, the photoreceptors cease releasing glutamate, which relieves the ON bipolar cells from inhibition, activating them; this simultaneously removes the excitation from the OFF bipolar cells, silencing them.
兴奋性和抑制性神经递质之间的区别不是绝对的。相反，它取决于突触后神经元上存在的化学受体的类别。原则上，一个神经元，释放一种神经递质，可以对某些目标产生兴奋作用，对其他目标产生抑制作用，对其他目标仍有调节作用。例如，视网膜上的感光细胞在没有光的情况下不断释放神经递质谷氨酸。像大多数神经元一样，所谓的关闭双极细胞被释放的谷氨酸所激发。然而，被称为ON双极细胞的邻近目标神经元反而受到谷氨酸的抑制，因为它们缺乏典型的离子型谷氨酸受体，而是表达一类抑制性的代谢型谷氨酸受体。当有光时，光感受器停止释放谷氨酸，这解除了ON双极细胞的抑制，激活了它们；这同时消除了OFF双极细胞的兴奋，使它们沉默。
It is possible to identify the type of inhibitory effect a presynaptic neuron will have on a postsynaptic neuron, based on the proteins the presynaptic neuron expresses. [[Parvalbumin]]-expressing neurons typically dampen the output signal of the postsynaptic neuron in the [[visual cortex]], whereas [[somatostatin]]-expressing neurons typically block dendritic inputs to the postsynaptic neuron.<ref name="pmid22878717">{{cite journal | vauthors = Wilson NR, Runyan CA, Wang FL, Sur M | title = Division and subtraction by distinct cortical inhibitory networks in vivo | journal = Nature | volume = 488 | issue = 7411 | pages = 343–8 | date = August 2012 | pmid = 22878717 | pmc = 3653570 | doi = 10.1038/nature11347 | bibcode = 2012Natur.488..343W | hdl = 1721.1/92709 }}</ref>
It is possible to identify the type of inhibitory effect a presynaptic neuron will have on a postsynaptic neuron, based on the proteins the presynaptic neuron expresses. [[Parvalbumin]]-expressing neurons typically dampen the output signal of the postsynaptic neuron in the [[visual cortex]], whereas [[somatostatin]]-expressing neurons typically block dendritic inputs to the postsynaptic neuron.<ref name="pmid22878717">{{cite journal | vauthors = Wilson NR, Runyan CA, Wang FL, Sur M | title = Division and subtraction by distinct cortical inhibitory networks in vivo | journal = Nature | volume = 488 | issue = 7411 | pages = 343–8 | date = August 2012 | pmid = 22878717 | pmc = 3653570 | doi = 10.1038/nature11347 | bibcode = 2012Natur.488..343W | hdl = 1721.1/92709 }}</ref>
根据突触前神经元表达的蛋白质，可以确定突触前神经元对突触后神经元的抑制作用的类型。表达副白蛋白的神经元通常会抑制视觉皮层中突触后神经元的输出信号，而表达躯干素的神经元通常会阻断突触后神经元的树突输入。
====Discharge patterns====
====Discharge patterns放电模式====
Neurons have intrinsic electroresponsive properties like intrinsic transmembrane voltage [[Neural oscillation|oscillatory]] patterns.<ref name="llinas2014">{{cite journal | vauthors = Llinás RR | title = Intrinsic electrical properties of mammalian neurons and CNS function: a historical perspective | journal = Frontiers in Cellular Neuroscience | volume = 8 | pages = 320 | date = 2014-01-01 | pmid = 25408634 | pmc = 4219458 | doi = 10.3389/fncel.2014.00320 | doi-access = free }}</ref> So neurons can be classified according to their [[electrophysiology|electrophysiological]] characteristics:
Neurons have intrinsic electroresponsive properties like intrinsic transmembrane voltage [[Neural oscillation|oscillatory]] patterns.<ref name="llinas2014">{{cite journal | vauthors = Llinás RR | title = Intrinsic electrical properties of mammalian neurons and CNS function: a historical perspective | journal = Frontiers in Cellular Neuroscience | volume = 8 | pages = 320 | date = 2014-01-01 | pmid = 25408634 | pmc = 4219458 | doi = 10.3389/fncel.2014.00320 | doi-access = free }}</ref> So neurons can be classified according to their [[electrophysiology|electrophysiological]] characteristics:
神经元具有内在的电反应特性，如内在的跨膜电压振荡模式。因此，可以根据神经元的电生理特性对其进行分类：
*Tonic or regular spiking. Some neurons are typically constantly (tonically) active, typically firing at a constant frequency. Example: interneurons in neurostriatum.
*Tonic or regular spiking. Some neurons are typically constantly (tonically) active, typically firing at a constant frequency. Example: interneurons in neurostriatum.
*快闪性。一些神经元因其高放电率而引人注目，例如某些类型的皮质抑制性中间神经元、苍白球、视网膜神经节细胞。
*快闪性。一些神经元因其高放电率而引人注目，例如某些类型的皮质抑制性中间神经元、苍白球、视网膜神经节细胞。
====Neurotransmitter ====
====Neurotransmitter神经递质 ====
[[File:Neurotransmitters.jpg|thumb|Synaptic vesicles containing neurotransmitters]]
[[File:Neurotransmitters.jpg|thumb|Synaptic vesicles containing neurotransmitters含有神经递质的突触小泡。]]
{{Main|Neurotransmitter}}
{{Main|Neurotransmitter}}
[[Neurotransmitter]]s are chemical messengers passed from one neuron to another neuron or to a [[muscle cell]] or [[Gland|gland cell]].
[[Neurotransmitter]]s are chemical messengers passed from one neuron to another neuron or to a [[muscle cell]] or [[Gland|gland cell]].
神经递质是由一个神经元传递给另一个神经元或肌肉细胞或腺体细胞的化学信使。
神经递质是由一个神经元传递给另一个神经元或肌肉细胞或腺体细胞的化学信使。
*组胺能神经元——组胺。组胺是一种单胺类神经递质和神经调节剂。产生组胺的神经元存在于下丘脑的管状乳头核。 组胺参与唤醒和调节睡眠/觉醒行为。
*组胺能神经元——组胺。组胺是一种单胺类神经递质和神经调节剂。产生组胺的神经元存在于下丘脑的管状乳头核。 组胺参与唤醒和调节睡眠/觉醒行为。
====Multimodel classification====
====Multimodel classification多模式分类====
Since 2012 there has been a push from the cellular and computational neuroscience community to come up with a universal classification of neurons that will apply to all neurons in the brain as well as across species. This is done by considering the three essential qualities of all neurons: electrophysiology, morphology, and the individual transcriptome of the cells. Besides being universal this classification has the advantage of being able to classify astrocytes as well. A method called Patch-Seq in which all three qualities can be measured at once is used extensively by the Allen Institute for Brain Science.<ref>{{cite web |url=https://www.news-medical.net/news/20201203/Patch-seq-technique-helps-depict-the-variation-of-neural-cells-in-the-brain.aspx |title=Patch-seq technique helps depict the variation of neural cells in the brain |work=News-medical.net |date=3 December 2020 |access-date=26 August 2021 |url-status=live}}</ref>
Since 2012 there has been a push from the cellular and computational neuroscience community to come up with a universal classification of neurons that will apply to all neurons in the brain as well as across species. This is done by considering the three essential qualities of all neurons: electrophysiology, morphology, and the individual transcriptome of the cells. Besides being universal this classification has the advantage of being able to classify astrocytes as well. A method called Patch-Seq in which all three qualities can be measured at once is used extensively by the Allen Institute for Brain Science.<ref>{{cite web |url=https://www.news-medical.net/news/20201203/Patch-seq-technique-helps-depict-the-variation-of-neural-cells-in-the-brain.aspx |title=Patch-seq technique helps depict the variation of neural cells in the brain |work=News-medical.net |date=3 December 2020 |access-date=26 August 2021 |url-status=live}}</ref>
自2012年以来，细胞和计算神经科学界一直在推动提出一个通用的神经元分类，该分类将适用于大脑中的所有神经元以及跨物种。这是通过考虑所有神经元的三个基本属性来实现的：电生理学、形态学和细胞的个体转录组。除了具有普遍性之外，这种分类法还有一个优点，就是能够对星形胶质细胞进行分类。艾伦脑科学研究所广泛使用一种叫做Patch-Seq的方法，可以同时测量所有三种属性。
自2012年以来，细胞和计算神经科学界一直在推动提出一个通用的神经元分类，该分类将适用于大脑中的所有神经元以及跨物种。这是通过考虑所有神经元的三个基本属性来实现的：电生理学、形态学和细胞的个体转录组。除了具有普遍性之外，这种分类法还有一个优点，就是能够对星形胶质细胞进行分类。艾伦脑科学研究所广泛使用一种叫做Patch-Seq的方法，可以同时测量所有三种属性。
==Connectivity==
==Connectivity连接性==
{{Main|Synapse|Chemical synapse}}
{{Main|Synapse|Chemical synapse化学突触}}
[[File:Chemical synapse schema cropped.jpg|thumb|right|350px|A signal propagating down an axon to the cell body and dendrites of the next cell]]
[[File:Chemical synapse schema cropped.jpg|thumb|right|350px|A signal propagating down an axon to the cell body and dendrites of the next cell沿着轴突传播到下一个细胞的细胞体和树突的一种信号。]]
[[File:Neuro Muscular Junction.png|thumb|Chemical synapse|left]]
[[File:Neuro Muscular Junction.png|thumb|Chemical synapse|left]]
Neurons communicate with each other via [[synapses]], where either the [[axon terminal]] of one cell contacts another neuron's dendrite, soma or, less commonly, axon. Neurons such as Purkinje cells in the cerebellum can have over 1000 dendritic branches, making connections with tens of thousands of other cells; other neurons, such as the magnocellular neurons of the [[supraoptic nucleus]], have only one or two dendrites, each of which receives thousands of synapses.
Neurons communicate with each other via [[synapses]], where either the [[axon terminal]] of one cell contacts another neuron's dendrite, soma or, less commonly, axon. Neurons such as Purkinje cells in the cerebellum can have over 1000 dendritic branches, making connections with tens of thousands of other cells; other neurons, such as the magnocellular neurons of the [[supraoptic nucleus]], have only one or two dendrites, each of which receives thousands of synapses.
神经元通过突触相互沟通，一个细胞的轴突终端接触到另一个神经元的树突、胞体，或者更少见的轴突。像小脑中的浦肯野细胞这样的神经元可以有超过1000个树突分支，与成千上万的其他细胞建立连接; 其他的神经元，如视上核的大细胞神经元，只有一个或两个树突，每个树突接收数千个突触。
神经元通过突触相互沟通，一个细胞的轴突终端接触到另一个神经元的树突、胞体，或者更少见的轴突。像小脑中的浦肯野细胞这样的神经元可以有超过1000个树突分支，与成千上万的其他细胞建立连接; 其他的神经元，如视上核的大细胞神经元，只有一个或两个树突，每个树突接收数千个突触。
Synapses can be [[EPSP|excitatory]] or [[IPSP|inhibitory]], either increasing or decreasing activity in the target neuron, respectively. Some neurons also communicate via electrical synapses, which are direct, electrically conductive [[gap junction|junctions]] between cells.<ref>{{cite book |last1=Macpherson |first1=Gordon |title=Black's Medical Dictionary |date=2002 |publisher=Scarecrow Press |location=Lanham, MD |isbn=0810849844 |pages=431–434 |edition=40 }}</ref>
Synapses can be [[EPSP|excitatory]] or [[IPSP|inhibitory]], either increasing or decreasing activity in the target neuron, respectively. Some neurons also communicate via electrical synapses, which are direct, electrically conductive [[gap junction|junctions]] between cells.<ref>{{cite book |last1=Macpherson |first1=Gordon |title=Black's Medical Dictionary |date=2002 |publisher=Scarecrow Press |location=Lanham, MD |isbn=0810849844 |pages=431–434 |edition=40 }}</ref>
突触可以是兴奋性的或抑制性的，分别增加或减少目标神经元的活动。一些神经元还通过电突触进行交流，电突触是细胞之间直接的、导电的连接点。
When an action potential reaches the axon terminal, it opens [[Voltage-dependent calcium channel|voltage-gated calcium channels]], allowing [[Calcium in biology|calcium ions]] to enter the terminal. Calcium causes [[synaptic vesicles]] filled with neurotransmitter molecules to fuse with the membrane, releasing their contents into the synaptic cleft. The neurotransmitters diffuse across the synaptic cleft and activate receptors on the postsynaptic neuron. High cytosolic calcium in the [[axon terminal]] triggers mitochondrial calcium uptake, which, in turn, activates mitochondrial [[energy metabolism]] to produce [[Adenosine triphosphate|ATP]] to support continuous neurotransmission.<ref name="pmid23746507">{{cite journal | vauthors = Ivannikov MV, Macleod GT | title = Mitochondrial free Ca²⁺ levels and their effects on energy metabolism in Drosophila motor nerve terminals | journal = Biophysical Journal | volume = 104 | issue = 11 | pages = 2353–61 | date = June 2013 | pmid = 23746507 | pmc = 3672877 | doi = 10.1016/j.bpj.2013.03.064 | bibcode = 2013BpJ...104.2353I }}</ref>
When an action potential reaches the axon terminal, it opens [[Voltage-dependent calcium channel|voltage-gated calcium channels]], allowing [[Calcium in biology|calcium ions]] to enter the terminal. Calcium causes [[synaptic vesicles]] filled with neurotransmitter molecules to fuse with the membrane, releasing their contents into the synaptic cleft. The neurotransmitters diffuse across the synaptic cleft and activate receptors on the postsynaptic neuron. High cytosolic calcium in the [[axon terminal]] triggers mitochondrial calcium uptake, which, in turn, activates mitochondrial [[energy metabolism]] to produce [[Adenosine triphosphate|ATP]] to support continuous neurotransmission.<ref name="pmid23746507">{{cite journal | vauthors = Ivannikov MV, Macleod GT | title = Mitochondrial free Ca²⁺ levels and their effects on energy metabolism in Drosophila motor nerve terminals | journal = Biophysical Journal | volume = 104 | issue = 11 | pages = 2353–61 | date = June 2013 | pmid = 23746507 | pmc = 3672877 | doi = 10.1016/j.bpj.2013.03.064 | bibcode = 2013BpJ...104.2353I }}</ref>
当动作电位到达轴突末端时，它打开电压门控的钙离子通道，允许钙离子进入末端。钙离子使充满神经递质分子的突触小泡与膜融合，将其内容释放到突触间隙中。神经递质在突触间隙中扩散，激活突触后神经元上的受体。轴突末端的高细胞钙引发线粒体钙吸收，这反过来又激活了线粒体的能量代谢，产生ATP以支持持续的神经传递。
An [[autapse]] is a synapse in which a neuron's axon connects to its own dendrites.
An [[autapse]] is a synapse in which a neuron's axon connects to its own dendrites.
自突触是指神经元的轴突与自己的树突相连的突触。
The [[human brain]] has some 8.6 x 10<sup>10</sup> (eighty six billion) neurons.<ref>{{ cite journal | vauthors = Herculano-Houzel S | title = The human brain in numbers: a linearly scaled-up primate brain | journal = Frontiers in Human Neuroscience | volume = 3 | pages = 31 | date = November 2009 | pmid = 19915731 | doi = 10.3389/neuro.09.031.2009 | pmc = 2776484 | doi-access = free }}</ref> Each neuron has on average 7,000 synaptic connections to other neurons. It has been estimated that the brain of a three-year-old child has about 10<sup>15</sup> synapses (1 quadrillion). [[Synaptic pruning|This number declines with age]], stabilizing by adulthood. Estimates vary for an adult, ranging from 10<sup>14</sup> to 5 x 10<sup>14</sup> synapses (100 to 500 trillion).<ref>{{cite journal | vauthors = Drachman DA | title = Do we have brain to spare? | journal = Neurology | volume = 64 | issue = 12 | pages = 2004–5 | date = June 2005 | pmid = 15985565 | doi = 10.1212/01.WNL.0000166914.38327.BB | s2cid = 38482114 }}</ref>
[[File:Axon Propagation.svg|thumb|563x563px|An annotated diagram of the stages of an action potential propagating down an axon including the role of ion concentration and pump and channel proteins.一个动作电位沿轴突传播的阶段的注释图，包括离子浓度和泵及通道蛋白的作用。]]
[[File:Axon Propagation.svg|thumb|563x563px|An annotated diagram of the stages of an action potential propagating down an axon including the role of ion concentration and pump and channel proteins.]]
人脑有大约8.6 x 1010（86亿）个神经元。 每个神经元平均有7000个与其他神经元的突触连接。据估计，一个三岁孩子的大脑大约有1015个突触（1万亿）。这个数字随着年龄的增长而下降，到成年后趋于稳定。对成年人的估计有所不同，从1014到5 x 1014个突触（100到500万亿）不等。
=== Nonelectrochemical signaling非电化学信号传递 ===
Beyond electrical and chemical signaling, studies suggest neurons in healthy human brains can also communicate through:
Beyond electrical and chemical signaling, studies suggest neurons in healthy human brains can also communicate through:
* force generated by the enlargement of dendritic spines<ref>{{cite journal |last1=Ucar |first1=Hasan |last2=Watanabe |first2=Satoshi |last3=Noguchi |first3=Jun |last4=Morimoto |first4=Yuichi |last5=Iino |first5=Yusuke |last6=Yagishita |first6=Sho |last7=Takahashi |first7=Noriko |last8=Kasai |first8=Haruo |title=Mechanical actions of dendritic-spine enlargement on presynaptic exocytosis |journal=Nature |date=December 2021 |volume=600 |issue=7890 |pages=686–689 |doi=10.1038/s41586-021-04125-7 |language=en |issn=1476-4687}}<br/>Lay summary:<br/>{{cite news |title=Forceful synapses reveal mechanical interactions in the brain |url=https://www.nature.com/articles/d41586-021-03516-0 |access-date=21 February 2022 |work=Nature |date=24 November 2021 |language=en |doi=10.1038/d41586-021-03516-0}}</ref>
* force generated by the enlargement of dendritic spines<ref>{{cite journal |last1=Ucar |first1=Hasan |last2=Watanabe |first2=Satoshi |last3=Noguchi |first3=Jun |last4=Morimoto |first4=Yuichi |last5=Iino |first5=Yusuke |last6=Yagishita |first6=Sho |last7=Takahashi |first7=Noriko |last8=Kasai |first8=Haruo |title=Mechanical actions of dendritic-spine enlargement on presynaptic exocytosis |journal=Nature |date=December 2021 |volume=600 |issue=7890 |pages=686–689 |doi=10.1038/s41586-021-04125-7 |language=en |issn=1476-4687}}<br/>Lay summary:<br/>{{cite news |title=Forceful synapses reveal mechanical interactions in the brain |url=https://www.nature.com/articles/d41586-021-03516-0 |access-date=21 February 2022 |work=Nature |date=24 November 2021 |language=en |doi=10.1038/d41586-021-03516-0}}</ref>
* the transfer of [[protein]]s – transneuronally transported proteins (TNTPs)<!--e.g. between [[Retinal ganglion cell|RGC]] and [[Excitatory synapse|excitatory]] [[lateral geniculate nucleus|LGN]] neurons--><ref>{{cite news |title=Researchers discover new type of cellular communication in the brain |url=https://medicalxpress.com/news/2022-01-cellular-brain.html |access-date=12 February 2022 |work=The Scripps Research Institute |language=en}}</ref><ref>{{cite journal |last1=Schiapparelli |first1=Lucio M. |last2=Sharma |first2=Pranav |last3=He |first3=Hai-Yan |last4=Li |first4=Jianli |last5=Shah |first5=Sahil H. |last6=McClatchy |first6=Daniel B. |last7=Ma |first7=Yuanhui |last8=Liu |first8=Han-Hsuan |last9=Goldberg |first9=Jeffrey L. |last10=Yates |first10=John R. |last11=Cline |first11=Hollis T. |title=Proteomic screen reveals diverse protein transport between connected neurons in the visual system |journal=Cell Reports |date=25 January 2022 |volume=38 |issue=4 |doi=10.1016/j.celrep.2021.110287 |language=English |issn=2211-1247}}</ref>
* the transfer of [[protein]]s – transneuronally transported proteins (TNTPs)<!--e.g. between [[Retinal ganglion cell|RGC]] and [[Excitatory synapse|excitatory]] [[lateral geniculate nucleus|LGN]] neurons--><ref>{{cite news |title=Researchers discover new type of cellular communication in the brain |url=https://medicalxpress.com/news/2022-01-cellular-brain.html |access-date=12 February 2022 |work=The Scripps Research Institute |language=en}}</ref><ref>{{cite journal |last1=Schiapparelli |first1=Lucio M. |last2=Sharma |first2=Pranav |last3=He |first3=Hai-Yan |last4=Li |first4=Jianli |last5=Shah |first5=Sahil H. |last6=McClatchy |first6=Daniel B. |last7=Ma |first7=Yuanhui |last8=Liu |first8=Han-Hsuan |last9=Goldberg |first9=Jeffrey L. |last10=Yates |first10=John R. |last11=Cline |first11=Hollis T. |title=Proteomic screen reveals diverse protein transport between connected neurons in the visual system |journal=Cell Reports |date=25 January 2022 |volume=38 |issue=4 |doi=10.1016/j.celrep.2021.110287 |language=English |issn=2211-1247}}</ref>
除了电和化学信号，研究表明健康人脑中的神经元还可以通过以下方式交流：
* force generated by the enlargement of dendritic spines<br/>Lay summary:<br/>
*树突棘扩大产生的力
* the transfer of proteins – transneuronally transported proteins (TNTPs)
*蛋白质的转移--经神经元转运蛋白（TNTPs）。
They can also get modulated by input from the environment and [[hormone]]s released from other parts of the organism,<ref>{{cite journal |last1=Levitan |first1=Irwin B. |last2=Kaczmarek |first2=Leonard K. |title=Electrical Signaling in Neurons |doi=10.1093/med/9780199773893.001.0001/med-9780199773893-chapter-3 |publisher=Oxford University Press}}</ref> which could be influenced more or less directly by neurons. This also applies to [[neurotrophin]]s such as [[BDNF]]. The [[gut microbiome]] is also connected with the brain.<ref>{{cite journal |last1=O’Leary |first1=Olivia F. |last2=Ogbonnaya |first2=Ebere S. |last3=Felice |first3=Daniela |last4=Levone |first4=Brunno R. |last5=C. Conroy |first5=Lorraine |last6=Fitzgerald |first6=Patrick |last7=Bravo |first7=Javier A. |last8=Forsythe |first8=Paul |last9=Bienenstock |first9=John |last10=Dinan |first10=Timothy G. |last11=Cryan |first11=John F. |title=The vagus nerve modulates BDNF expression and neurogenesis in the hippocampus |journal=European Neuropsychopharmacology |date=1 February 2018 |volume=28 |issue=2 |pages=307–316 |doi=10.1016/j.euroneuro.2017.12.004 |language=en |issn=0924-977X}}</ref>
They can also get modulated by input from the environment and [[hormone]]s released from other parts of the organism,<ref>{{cite journal |last1=Levitan |first1=Irwin B. |last2=Kaczmarek |first2=Leonard K. |title=Electrical Signaling in Neurons |doi=10.1093/med/9780199773893.001.0001/med-9780199773893-chapter-3 |publisher=Oxford University Press}}</ref> which could be influenced more or less directly by neurons. This also applies to [[neurotrophin]]s such as [[BDNF]]. The [[gut microbiome]] is also connected with the brain.<ref>{{cite journal |last1=O’Leary |first1=Olivia F. |last2=Ogbonnaya |first2=Ebere S. |last3=Felice |first3=Daniela |last4=Levone |first4=Brunno R. |last5=C. Conroy |first5=Lorraine |last6=Fitzgerald |first6=Patrick |last7=Bravo |first7=Javier A. |last8=Forsythe |first8=Paul |last9=Bienenstock |first9=John |last10=Dinan |first10=Timothy G. |last11=Cryan |first11=John F. |title=The vagus nerve modulates BDNF expression and neurogenesis in the hippocampus |journal=European Neuropsychopharmacology |date=1 February 2018 |volume=28 |issue=2 |pages=307–316 |doi=10.1016/j.euroneuro.2017.12.004 |language=en |issn=0924-977X}}</ref>
它们也可以被来自环境的输入和机体其他部分释放的激素所调控， 这些都可以或多或少地被神经元直接影响。这也适用于神经营养素，如BDNF。肠道微生物组也与大脑有关 。
==Mechanisms for propagating action potentials==
==Mechanisms for propagating action potentials动作电位的传播机制==
In 1937 [[John Zachary Young]] suggested that the [[squid giant axon]] could be used to study neuronal electrical properties.<ref>{{cite web |first = Eric H. |last = Chudler | name-list-style = vanc |title = Milestones in Neuroscience Research |url = http://faculty.washington.edu/chudler/hist.html |work = Neuroscience for Kids |access-date = 2009-06-20}}</ref> It is larger than but similar to human neurons, making it easier to study. By inserting electrodes into the squid giant axons, accurate measurements were made of the [[membrane potential]].
In 1937 [[John Zachary Young]] suggested that the [[squid giant axon]] could be used to study neuronal electrical properties.<ref>{{cite web |first = Eric H. |last = Chudler | name-list-style = vanc |title = Milestones in Neuroscience Research |url = http://faculty.washington.edu/chudler/hist.html |work = Neuroscience for Kids |access-date = 2009-06-20}}</ref> It is larger than but similar to human neurons, making it easier to study. By inserting electrodes into the squid giant axons, accurate measurements were made of the [[membrane potential]].
1937年，约翰-扎卡里-杨提出，乌贼巨大轴突可用于研究神经元的电特性。 它比人类神经元大，但与人类神经元相似，因此更容易研究。通过将电极插入乌贼巨轴突，对膜电位进行了精确测量。
The cell membrane of the axon and soma contain voltage-gated ion channels that allow the neuron to generate and propagate an electrical signal (an action potential). Some neurons also generate [[subthreshold membrane potential oscillations]]. These signals are generated and propagated by charge-carrying [[ions]] including sodium (Na<sup>+</sup>), potassium (K<sup>+</sup>), chloride (Cl<sup>−</sup>), and [[Calcium signaling|calcium (Ca<sup>2+</sup>)]].
The cell membrane of the axon and soma contain voltage-gated ion channels that allow the neuron to generate and propagate an electrical signal (an action potential). Some neurons also generate [[subthreshold membrane potential oscillations]]. These signals are generated and propagated by charge-carrying [[ions]] including sodium (Na<sup>+</sup>), potassium (K<sup>+</sup>), chloride (Cl<sup>−</sup>), and [[Calcium signaling|calcium (Ca<sup>2+</sup>)]].
轴突和胞体的细胞膜含有电压门控离子通道，使神经元能够产生和传播电信号（动作电位）。一些神经元还产生阈下膜电位振荡。这些信号是由携带电荷的离子产生和传播的，包括钠（Na+）、钾（K+）、氯（Cl-）和钙（Ca2+）。
Several stimuli can activate a neuron leading to electrical activity, including [[Mechanoreceptor|pressure]], stretch, chemical transmitters, and changes of the electric potential across the cell membrane.<ref>{{cite web|first1=Joe |last1=Patlak |first2=Ray |last2=Gibbons | name-list-style = vanc |title=Electrical Activity of Nerves |url=http://physioweb.med.uvm.edu/cardiacep/EP/nervecells.htm |work=Action Potentials in Nerve Cells |date=2000-11-01 |access-date=2009-06-20 |url-status=dead |archive-url=https://web.archive.org/web/20090827220335/http://physioweb.med.uvm.edu/cardiacep/EP/nervecells.htm |archive-date=August 27, 2009 }}</ref> Stimuli cause specific ion-channels within the cell membrane to open, leading to a flow of ions through the cell membrane, changing the membrane potential. Neurons must maintain the specific electrical properties that define their neuron type.<ref name="Harris-Warrick">{{cite journal |last1=Harris-Warrick |first1=RM |title=Neuromodulation and flexibility in Central Pattern Generator networks. |journal=Current Opinion in Neurobiology |date=October 2011 |volume=21 |issue=5 |pages=685–92 |doi=10.1016/j.conb.2011.05.011 |pmid=21646013|pmc=3171584 }}</ref>
Several stimuli can activate a neuron leading to electrical activity, including [[Mechanoreceptor|pressure]], stretch, chemical transmitters, and changes of the electric potential across the cell membrane.<ref>{{cite web|first1=Joe |last1=Patlak |first2=Ray |last2=Gibbons | name-list-style = vanc |title=Electrical Activity of Nerves |url=http://physioweb.med.uvm.edu/cardiacep/EP/nervecells.htm |work=Action Potentials in Nerve Cells |date=2000-11-01 |access-date=2009-06-20 |url-status=dead |archive-url=https://web.archive.org/web/20090827220335/http://physioweb.med.uvm.edu/cardiacep/EP/nervecells.htm |archive-date=August 27, 2009 }}</ref> Stimuli cause specific ion-channels within the cell membrane to open, leading to a flow of ions through the cell membrane, changing the membrane potential. Neurons must maintain the specific electrical properties that define their neuron type.<ref name="Harris-Warrick">{{cite journal |last1=Harris-Warrick |first1=RM |title=Neuromodulation and flexibility in Central Pattern Generator networks. |journal=Current Opinion in Neurobiology |date=October 2011 |volume=21 |issue=5 |pages=685–92 |doi=10.1016/j.conb.2011.05.011 |pmid=21646013|pmc=3171584 }}</ref>
有几种刺激可以激活神经元，导致电活动，包括压力、拉伸、化学传导物和细胞膜上的电势变化。 刺激导致细胞膜内特定的离子通道打开，使得离子流经细胞膜，改变膜电位。神经元必须保持界定其神经元类型的特定电特性 。
Thin neurons and axons require less [[metabolism|metabolic]] expense to produce and carry action potentials, but thicker axons convey impulses more rapidly. To minimize metabolic expense while maintaining rapid conduction, many neurons have insulating sheaths of [[myelin]] around their axons. The sheaths are formed by [[glia]]l cells: [[oligodendrocyte]]s in the central nervous system and [[Schwann cell]]s in the peripheral nervous system. The sheath enables action potentials to travel [[saltatory conduction|faster]] than in unmyelinated axons of the same diameter, whilst using less energy. The myelin sheath in peripheral nerves normally runs along the axon in sections about 1 mm long, punctuated by unsheathed [[node of Ranvier|nodes of Ranvier]], which contain a high density of voltage-gated ion channels. [[Multiple sclerosis]] is a neurological disorder that results from demyelination of axons in the central nervous system.
Thin neurons and axons require less [[metabolism|metabolic]] expense to produce and carry action potentials, but thicker axons convey impulses more rapidly. To minimize metabolic expense while maintaining rapid conduction, many neurons have insulating sheaths of [[myelin]] around their axons. The sheaths are formed by [[glia]]l cells: [[oligodendrocyte]]s in the central nervous system and [[Schwann cell]]s in the peripheral nervous system. The sheath enables action potentials to travel [[saltatory conduction|faster]] than in unmyelinated axons of the same diameter, whilst using less energy. The myelin sheath in peripheral nerves normally runs along the axon in sections about 1 mm long, punctuated by unsheathed [[node of Ranvier|nodes of Ranvier]], which contain a high density of voltage-gated ion channels. [[Multiple sclerosis]] is a neurological disorder that results from demyelination of axons in the central nervous system.
薄的神经元和轴突需要较少的代谢支出来产生和传导动作电位，但较粗的轴突能更快地传递冲动。为了在保持快速传导的同时尽量减少代谢支出，许多神经元的轴突周围有绝缘的髓鞘。这些髓鞘是由胶质细胞形成的：中枢神经系统的少突胶质细胞和周围神经系统的许旺细胞。髓鞘使得动作电位比相同直径的无髓轴突走得更快，同时消耗更少的能量。周围神经中的髓鞘通常沿着轴突生长，长度约为1毫米，并且点缀着无髓鞘的郎飞氏结，其中包含高密度的电压门控离子通道。多发性硬化症是一种神经系统疾病，由中枢神经系统中轴突的脱髓鞘导致。
Some neurons do not generate action potentials, but instead generate a [[graded potential|graded electrical signal]], which in turn causes graded neurotransmitter release. Such [[non-spiking neurons]] tend to be sensory neurons or interneurons, because they cannot carry signals long distances.
Some neurons do not generate action potentials, but instead generate a [[graded potential|graded electrical signal]], which in turn causes graded neurotransmitter release. Such [[non-spiking neurons]] tend to be sensory neurons or interneurons, because they cannot carry signals long distances.
有些神经元不产生动作电位，而是产生一个分级的电信号，反过来引起分级的神经递质释放。这样的非脉冲神经元往往是感觉神经元或中间神经元，因为它们不能长距离携带信号。
==Neural coding神经编码==
==Neural coding==
[[Neural coding]] is concerned with how sensory and other information is represented in the brain by neurons. The main goal of studying neural coding is to characterize the relationship between the [[Stimulus (physiology)|stimulus]] and the individual or [[Neural ensemble|ensemble]] neuronal responses, and the relationships among the electrical activities of the neurons within the ensemble.<ref name="Brown">{{cite journal | vauthors = Brown EN, Kass RE, Mitra PP | title = Multiple neural spike train data analysis: state-of-the-art and future challenges | journal = Nature Neuroscience | volume = 7 | issue = 5 | pages = 456–61 | date = May 2004 | pmid = 15114358 | doi = 10.1038/nn1228 | s2cid = 562815 }}</ref> It is thought that neurons can encode both [[Digital data|digital]] and [[analog signal|analog]] information.<ref>{{cite book | vauthors = Thorpe SJ |chapter=Spike arrival times: A highly efficient coding scheme for neural networks |chapter-url= http://pop.cerco.ups-tlse.fr/fr_vers/documents/thorpe_sj_90_91.pdf |pages= 91–94 |title=Parallel processing in neural systems and computers| veditors = Eckmiller R, Hartmann G, Hauske G |date=1990|publisher=North-Holland|isbn=9780444883902 |url={{google books |plainurl=y |id=boBqAAAAMAAJ}}|language=en|archive-url=https://web.archive.org/web/20120215151304/http://pop.cerco.ups-tlse.fr/fr_vers/documents/thorpe_sj_90_91.pdf|archive-date=2012-02-15}}</ref>
[[Neural coding]] is concerned with how sensory and other information is represented in the brain by neurons. The main goal of studying neural coding is to characterize the relationship between the [[Stimulus (physiology)|stimulus]] and the individual or [[Neural ensemble|ensemble]] neuronal responses, and the relationships among the electrical activities of the neurons within the ensemble.<ref name="Brown">{{cite journal | vauthors = Brown EN, Kass RE, Mitra PP | title = Multiple neural spike train data analysis: state-of-the-art and future challenges | journal = Nature Neuroscience | volume = 7 | issue = 5 | pages = 456–61 | date = May 2004 | pmid = 15114358 | doi = 10.1038/nn1228 | s2cid = 562815 }}</ref> It is thought that neurons can encode both [[Digital data|digital]] and [[analog signal|analog]] information.<ref>{{cite book | vauthors = Thorpe SJ |chapter=Spike arrival times: A highly efficient coding scheme for neural networks |chapter-url= http://pop.cerco.ups-tlse.fr/fr_vers/documents/thorpe_sj_90_91.pdf |pages= 91–94 |title=Parallel processing in neural systems and computers| veditors = Eckmiller R, Hartmann G, Hauske G |date=1990|publisher=North-Holland|isbn=9780444883902 |url={{google books |plainurl=y |id=boBqAAAAMAAJ}}|language=en|archive-url=https://web.archive.org/web/20120215151304/http://pop.cerco.ups-tlse.fr/fr_vers/documents/thorpe_sj_90_91.pdf|archive-date=2012-02-15}}</ref>
神经编码关注的是感觉和其他信息如何在大脑中被神经元所表达。研究神经编码的主要目的是描述刺激与单个或集合神经元反应之间的关系，以及集合内神经元电活动之间的关系。 人们认为，神经元既可以编码数字信息，也可以编码模拟信息。
==All-or-none principle全有或全无原则==
[[File:All-or-none_law_en.svg|thumb|318x318px|As long as the stimulus reaches the threshold, the full response would be given. Larger stimulus does not result in a larger response, vice versa.只要刺激达到阈值，就会有充分的反应。较大的刺激不会导致较大的反应，反之亦然。<ref name=":0">{{Cite book|title=Biological psychology|last=Kalat, James W|year=2016|isbn=9781305105409|edition=12|location=Australia|oclc=898154491}}</ref>{{Rp|31}}]]
[[File:All-or-none_law_en.svg|thumb|318x318px|As long as the stimulus reaches the threshold, the full response would be given. Larger stimulus does not result in a larger response, vice versa.<ref name=":0">{{Cite book|title=Biological psychology|last=Kalat, James W|year=2016|isbn=9781305105409|edition=12|location=Australia|oclc=898154491}}</ref>{{Rp|31}}]]
{{Main|All-or-none law}}
{{Main|All-or-none law}}
The conduction of nerve impulses is an example of an [[All-or-none law|all-or-none]] response. In other words, if a neuron responds at all, then it must respond completely. Greater intensity of stimulation, like brighter image/louder sound, does not produce a stronger signal, but can increase firing frequency.<ref name=":0" />{{Rp|31}} Receptors respond in different ways to stimuli. Slowly adapting or [[tonic (physiology)|tonic receptors]] respond to steady stimulus and produce a steady rate of firing. Tonic receptors most often respond to increased intensity of stimulus by increasing their firing frequency, usually as a power function of stimulus plotted against impulses per second. This can be likened to an intrinsic property of light where greater intensity of a specific frequency (color) requires more photons, as the photons can't become "stronger" for a specific frequency.
The conduction of nerve impulses is an example of an [[All-or-none law|all-or-none]] response. In other words, if a neuron responds at all, then it must respond completely. Greater intensity of stimulation, like brighter image/louder sound, does not produce a stronger signal, but can increase firing frequency.<ref name=":0" />{{Rp|31}} Receptors respond in different ways to stimuli. Slowly adapting or [[tonic (physiology)|tonic receptors]] respond to steady stimulus and produce a steady rate of firing. Tonic receptors most often respond to increased intensity of stimulus by increasing their firing frequency, usually as a power function of stimulus plotted against impulses per second. This can be likened to an intrinsic property of light where greater intensity of a specific frequency (color) requires more photons, as the photons can't become "stronger" for a specific frequency.
神经冲动的传导是一个全有或全无反应的例子。换句话说，如果一个神经元有任何反应，那么它必须完全响应。更大的刺激强度，如更亮的图像/更响的声音，不会产生更强的信号，但可以增加放电频率。[34]：31受体以不同方式回应刺激。缓慢适应的或紧张性的受体对稳定的刺激作出响应，并产生稳定的放电率。紧张性受体最常通过增加其放电频率对刺激强度的增加作出反应，通常是一个与每秒钟的脉冲相关的刺激的幂函数。这可以比喻为光的内在属性，即一个特定频率（颜色）的更大强度需要更多的光子，因为光子不能对一个特定频率变得 "更强"。
Other receptor types include quickly adapting or phasic receptors, where firing decreases or stops with steady stimulus; examples include [[Human skin|skin]] which, when touched causes neurons to fire, but if the object maintains even pressure, the neurons stop firing. The neurons of the skin and muscles that are responsive to pressure and vibration have filtering accessory structures that aid their function.
Other receptor types include quickly adapting or phasic receptors, where firing decreases or stops with steady stimulus; examples include [[Human skin|skin]] which, when touched causes neurons to fire, but if the object maintains even pressure, the neurons stop firing. The neurons of the skin and muscles that are responsive to pressure and vibration have filtering accessory structures that aid their function.
其他受体类型包括时相性或瞬变性受体，其放电随着稳定的刺激而减少或停止；比如包括皮肤，当被触摸时引起神经元放电，但如果物体保持均匀的压力，神经元就停止放电。对压力和振动有反应的皮肤和肌肉的神经元有过滤的附属结构来帮助它们发挥作用。
The [[pacinian corpuscle]] is one such structure. It has concentric layers like an onion, which form around the axon terminal. When pressure is applied and the corpuscle is deformed, mechanical stimulus is transferred to the axon, which fires. If the pressure is steady, stimulus ends; thus, typically these neurons respond with a transient depolarization during the initial deformation and again when the pressure is removed, which causes the corpuscle to change shape again. Other types of adaptation are important in extending the function of a number of other neurons.<ref>{{cite book | last1 = Eckert | first1 = Roger | last2 = Randall | first2 = David | name-list-style = vanc | title = Animal physiology: mechanisms and adaptations | year = 1983 | publisher = W.H. Freeman | location = San Francisco | isbn = 978-0-7167-1423-1 | page = [https://archive.org/details/animalphysiology0000ecke/page/239 239] | url = https://archive.org/details/animalphysiology0000ecke/page/239 }}</ref>
The [[pacinian corpuscle]] is one such structure. It has concentric layers like an onion, which form around the axon terminal. When pressure is applied and the corpuscle is deformed, mechanical stimulus is transferred to the axon, which fires. If the pressure is steady, stimulus ends; thus, typically these neurons respond with a transient depolarization during the initial deformation and again when the pressure is removed, which causes the corpuscle to change shape again. Other types of adaptation are important in extending the function of a number of other neurons.<ref>{{cite book | last1 = Eckert | first1 = Roger | last2 = Randall | first2 = David | name-list-style = vanc | title = Animal physiology: mechanisms and adaptations | year = 1983 | publisher = W.H. Freeman | location = San Francisco | isbn = 978-0-7167-1423-1 | page = [https://archive.org/details/animalphysiology0000ecke/page/239 239] | url = https://archive.org/details/animalphysiology0000ecke/page/239 }}</ref>
帕西尼氏小体就是这样一个结构。它有像洋葱一样的同心层，围绕着轴突终端形成。当施加压力使小体变形时，机械刺激被转移到轴突上，轴突就会放电。如果压力是稳定的，刺激就会结束；因此，通常这些神经元在最初的变形过程中会有短暂的去极化反应，而当压力被移除时又会有短暂的去极化反应，从而使小体再次改变形状。其他类型的适应对扩展其他一些神经元的功能很重要。[35]
==Etymology and spelling词源和拼写==
==Etymology and spelling==
The German anatomist [[Heinrich Wilhelm Gottfried von Waldeyer-Hartz|Heinrich Wilhelm Waldeyer]] introduced the term ''neuron'' in 1891,<ref name="finger"/> based on the [[Greek language|ancient Greek]] νεῦρον ''neuron'' 'sinew, cord, nerve'.<ref name="oed">''[[Oxford English Dictionary]]'', 3rd edition, 2003, ''s.v.''</ref>
The German anatomist [[Heinrich Wilhelm Gottfried von Waldeyer-Hartz|Heinrich Wilhelm Waldeyer]] introduced the term ''neuron'' in 1891,<ref name="finger"/> based on the [[Greek language|ancient Greek]] νεῦρον ''neuron'' 'sinew, cord, nerve'.<ref name="oed">''[[Oxford English Dictionary]]'', 3rd edition, 2003, ''s.v.''</ref>
德国解剖学家Heinrich Wilhelm Waldeyer于1891年提出了神经元一词，[36]其依据是古希腊语νεῦρον neuron's sinew, cord, nerve'。[37]
The word was adopted in French with the spelling ''neurone''. That spelling was also used by many writers in English,<ref name="mehta">{{cite journal | vauthors = Mehta AR, Mehta PR, Anderson SP, MacKinnon BL, Compston A | title = Grey Matter Etymology and the neuron(e) | journal = Brain | volume = 143 | issue = 1 | pages = 374–379 | date = January 2020 | pmid = 31844876 | pmc = 6935745 | doi = 10.1093/brain/awz367 | url = }}</ref> but has now become rare in American usage and uncommon in British usage.<ref name="ngram">{{cite web |title=Google Books Ngram Viewer |url=https://books.google.com/ngrams/graph?content=neuron%2Cneurone&year_start=1900&year_end=2008&case_insensitive=on&corpus=15&smoothing=3&direct_url=t4%3B%2Cneuron%3B%2Cc0%3B%2Cs0%3B%3Bneuron%3B%2Cc0%3B%3BNeuron%3B%2Cc0%3B%3BNEURON%3B%2Cc0%3B.t4%3B%2Cneurone%3B%2Cc0%3B%2Cs0%3B%3Bneurone%3B%2Cc0%3B%3BNeurone%3B%2Cc0%3B%3BNEURONE%3B%2Cc0 |website=books.google.com |access-date=19 December 2020 |language=en}}</ref><ref name="oed"/>
The word was adopted in French with the spelling ''neurone''. That spelling was also used by many writers in English,<ref name="mehta">{{cite journal | vauthors = Mehta AR, Mehta PR, Anderson SP, MacKinnon BL, Compston A | title = Grey Matter Etymology and the neuron(e) | journal = Brain | volume = 143 | issue = 1 | pages = 374–379 | date = January 2020 | pmid = 31844876 | pmc = 6935745 | doi = 10.1093/brain/awz367 | url = }}</ref> but has now become rare in American usage and uncommon in British usage.<ref name="ngram">{{cite web |title=Google Books Ngram Viewer |url=https://books.google.com/ngrams/graph?content=neuron%2Cneurone&year_start=1900&year_end=2008&case_insensitive=on&corpus=15&smoothing=3&direct_url=t4%3B%2Cneuron%3B%2Cc0%3B%2Cs0%3B%3Bneuron%3B%2Cc0%3B%3BNeuron%3B%2Cc0%3B%3BNEURON%3B%2Cc0%3B.t4%3B%2Cneurone%3B%2Cc0%3B%2Cs0%3B%3Bneurone%3B%2Cc0%3B%3BNeurone%3B%2Cc0%3B%3BNEURONE%3B%2Cc0 |website=books.google.com |access-date=19 December 2020 |language=en}}</ref><ref name="oed"/>
这个词以前在法语中被采用，拼写为neurone。这种拼法也曾被许多英语作家使用，[38]但现在在美国的用法中已经很少见，在英国的用法中也不常见。[39] [37]
==History历史==
{{Further|History of neuroscience}}
[[File:Golgi Hippocampus.jpg|left|thumb|Drawing by Camillo Golgi of a [[hippocampus]] stained using the [[silver nitrate]] method卡米洛-高尔基绘制的使用硝酸银法染色的海马体。]]
[[File:Purkinje cell by Cajal.png|thumb|Drawing of a Purkinje cell in the [[cerebellar cortex]] done by Santiago Ramón y Cajal, demonstrating the ability of Golgi's staining method to reveal fine detail圣地亚哥-拉蒙-卡亚尔（Santiago Ramón y Cajal）绘制的小脑皮层中的浦肯野细胞图，展示了高尔基染色法揭示精细细节的能力。]]
The neuron's place as the primary functional unit of the nervous system was first recognized in the late 19th century through the work of the Spanish anatomist [[Santiago Ramón y Cajal]].<ref name="López-Muñoz">{{cite journal | vauthors = López-Muñoz F, Boya J, Alamo C | title = Neuron theory, the cornerstone of neuroscience, on the centenary of the Nobel Prize award to Santiago Ramón y Cajal | journal = Brain Research Bulletin | volume = 70 | issue = 4–6 | pages = 391–405 | date = October 2006 | pmid = 17027775 | doi = 10.1016/j.brainresbull.2006.07.010 | s2cid = 11273256 }}</ref>
The neuron's place as the primary functional unit of the nervous system was first recognized in the late 19th century through the work of the Spanish anatomist [[Santiago Ramón y Cajal]].<ref name="López-Muñoz">{{cite journal | vauthors = López-Muñoz F, Boya J, Alamo C | title = Neuron theory, the cornerstone of neuroscience, on the centenary of the Nobel Prize award to Santiago Ramón y Cajal | journal = Brain Research Bulletin | volume = 70 | issue = 4–6 | pages = 391–405 | date = October 2006 | pmid = 17027775 | doi = 10.1016/j.brainresbull.2006.07.010 | s2cid = 11273256 }}</ref>
神经元作为神经系统主要功能单位的地位，在19世纪末通过西班牙解剖学家圣地亚哥-拉蒙-卡亚尔的作品首次得到承认。[40]
To make the structure of individual neurons visible, [[Santiago Ramón y Cajal|Ramón y Cajal]] improved a [[Golgi's method|silver staining process]] that had been developed by [[Camillo Golgi]].<ref name="López-Muñoz" /> The improved process involves a technique called "double impregnation" and is still in use.
To make the structure of individual neurons visible, [[Santiago Ramón y Cajal|Ramón y Cajal]] improved a [[Golgi's method|silver staining process]] that had been developed by [[Camillo Golgi]].<ref name="López-Muñoz" /> The improved process involves a technique called "double impregnation" and is still in use.
为了使单个神经元的结构清晰可见，Ramón y Cajal改进了Camillo Golgi开发的银染工艺。[40]改进后的工艺涉及一种称为 "双浸渍 "的技术，现在仍在使用。
In 1888 Ramón y Cajal published a paper about the bird cerebellum. In this paper, he stated that he could not find evidence for [[anastomosis]] between axons and dendrites and called each nervous element "an absolutely autonomous canton."<ref name="López-Muñoz" /><ref name="finger">{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|url=https://www.google.com/books/edition/_/BdRqAAAAMAAJ?hl=en&gbpv=1&pg=PA47|isbn=9780195146943|oclc=27151391|page=47 |quote=Ramon y Cajal's first paper on the Golgi stain was on the bird cerebellum, and it appeared in the ''Revista''<nowiki> in 1888. He acknowledged that he found the nerve fibers to be very intricate, but stated that he could find no evidence for either axons or dendrites undergoing anastomosis and forming nets. He called each nervous element 'an absolutely autonomous canton.'</nowiki>}}</ref> This became known as the [[neuron doctrine]], one of the central tenets of modern [[neuroscience]].<ref name="López-Muñoz" />
In 1888 Ramón y Cajal published a paper about the bird cerebellum. In this paper, he stated that he could not find evidence for [[anastomosis]] between axons and dendrites and called each nervous element "an absolutely autonomous canton."<ref name="López-Muñoz" /><ref name="finger">{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|url=https://www.google.com/books/edition/_/BdRqAAAAMAAJ?hl=en&gbpv=1&pg=PA47|isbn=9780195146943|oclc=27151391|page=47 |quote=Ramon y Cajal's first paper on the Golgi stain was on the bird cerebellum, and it appeared in the ''Revista''<nowiki> in 1888. He acknowledged that he found the nerve fibers to be very intricate, but stated that he could find no evidence for either axons or dendrites undergoing anastomosis and forming nets. He called each nervous element 'an absolutely autonomous canton.'</nowiki>}}</ref> This became known as the [[neuron doctrine]], one of the central tenets of modern [[neuroscience]].<ref name="López-Muñoz" />
1888年，Ramón y Cajal发表了一篇关于鸟类小脑的论文。在这篇论文中，他说他找不到轴突和树突之间结合的证据，并称每个神经元素为 "一个绝对自主的州县"[40] [36]，这被称为神经元学说，是现代神经科学的核心原则之一。[40]
In 1891, the German anatomist [[Heinrich Wilhelm Gottfried von Waldeyer-Hartz|Heinrich Wilhelm Waldeyer]] wrote a highly influential review of the neuron doctrine in which he introduced the term ''neuron'' to describe the anatomical and physiological unit of the nervous system.<ref>{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|url=https://www.google.com/books/edition/_/BdRqAAAAMAAJ?hl=en&gbpv=1&pg=PA47|isbn=9780195146943|oclc=27151391|page=47 |quote=... a man who would write a highly influential review of the evidence in favor of the neuron doctrine two years later. In his paper, Waldeyer (1891), ... , wrote that nerve cells terminate freely with end arborizations and that the 'neuron' is the anatomical and physiological unit of the nervous system. The word 'neuron' was born this way.}}</ref><ref>{{cite web|url=http://www.whonamedit.com/doctor.cfm/1846.html|title=Whonamedit - dictionary of medical eponyms|website=www.whonamedit.com|quote=Today, Wilhelm von Waldeyer-Hartz is remembered as the founder of the neurone theory, coining the term "neurone" to describe the cellular function unit of the nervous system and enunciating and clarifying that concept in 1891.}}</ref>
In 1891, the German anatomist [[Heinrich Wilhelm Gottfried von Waldeyer-Hartz|Heinrich Wilhelm Waldeyer]] wrote a highly influential review of the neuron doctrine in which he introduced the term ''neuron'' to describe the anatomical and physiological unit of the nervous system.<ref>{{Cite book|title=Origins of neuroscience : a history of explorations into brain function|last=Finger|first=Stanley|publisher=Oxford University Press|year=1994|url=https://www.google.com/books/edition/_/BdRqAAAAMAAJ?hl=en&gbpv=1&pg=PA47|isbn=9780195146943|oclc=27151391|page=47 |quote=... a man who would write a highly influential review of the evidence in favor of the neuron doctrine two years later. In his paper, Waldeyer (1891), ... , wrote that nerve cells terminate freely with end arborizations and that the 'neuron' is the anatomical and physiological unit of the nervous system. The word 'neuron' was born this way.}}</ref><ref>{{cite web|url=http://www.whonamedit.com/doctor.cfm/1846.html|title=Whonamedit - dictionary of medical eponyms|website=www.whonamedit.com|quote=Today, Wilhelm von Waldeyer-Hartz is remembered as the founder of the neurone theory, coining the term "neurone" to describe the cellular function unit of the nervous system and enunciating and clarifying that concept in 1891.}}</ref>
1891年，德国解剖学家Heinrich Wilhelm Waldeyer写了一篇对神经元学说有很大影响的综述，他在其中提出了神经元这一术语来描述神经系统的解剖学和生理学单位。[41] [42]
The silver impregnation stains are a useful method for [[Neuroanatomy|neuroanatomical]] investigations because, for reasons unknown, it stains only a small percentage of cells in a tissue, exposing the complete micro structure of individual neurons without much overlap from other cells.<ref name="Grant">{{cite journal | vauthors = Grant G | title = How the 1906 Nobel Prize in Physiology or Medicine was shared between Golgi and Cajal | journal = Brain Research Reviews | volume = 55 | issue = 2 | pages = 490–8 | date = October 2007 | pmid = 17306375 | doi = 10.1016/j.brainresrev.2006.11.004 | s2cid = 24331507 }}</ref>
The silver impregnation stains are a useful method for [[Neuroanatomy|neuroanatomical]] investigations because, for reasons unknown, it stains only a small percentage of cells in a tissue, exposing the complete micro structure of individual neurons without much overlap from other cells.<ref name="Grant">{{cite journal | vauthors = Grant G | title = How the 1906 Nobel Prize in Physiology or Medicine was shared between Golgi and Cajal | journal = Brain Research Reviews | volume = 55 | issue = 2 | pages = 490–8 | date = October 2007 | pmid = 17306375 | doi = 10.1016/j.brainresrev.2006.11.004 | s2cid = 24331507 }}</ref>
银浸渍染色法是神经解剖学研究的有效方法，因为——由于未知的原因——它只会对组织中的一小部分细胞进行染色，暴露出单个神经元的完整微观结构，而不会与其他细胞有太多的重叠。[43]
[[File:PurkinjeCell.jpg|thumb|Drawing of neurons in the pigeon [[cerebellum]], by Spanish neuroscientist [[Santiago Ramón y Cajal]] in 1899. (A) denotes [[Purkinje cell]]s and (B) denotes [[granule cells]], both of which are multipolar.]]
===Neuron doctrine神经元学说===
[[File:PurkinjeCell.jpg|thumb|Drawing of neurons in the pigeon [[cerebellum]], by Spanish neuroscientist [[Santiago Ramón y Cajal]] in 1899. (A) denotes [[Purkinje cell]]s and (B) denotes [[granule cells]], both of which are multipolar.鸽子小脑中的神经元图，由西班牙神经科学家圣地亚哥-拉蒙-卡亚尔于1899年绘制。(A）表示浦肯野细胞，（B）表示颗粒细胞，两者都是多极的。]]
The neuron doctrine is the now fundamental idea that neurons are the basic structural and functional units of the nervous system. The theory was put forward by Santiago Ramón y Cajal in the late 19th century. It held that neurons are discrete cells (not connected in a meshwork), acting as metabolically distinct units.
The neuron doctrine is the now fundamental idea that neurons are the basic structural and functional units of the nervous system. The theory was put forward by Santiago Ramón y Cajal in the late 19th century. It held that neurons are discrete cells (not connected in a meshwork), acting as metabolically distinct units.
神经元学说是现在的一个基本观点，即神经元是神经系统的基本结构和功能单位。该理论是由圣地亚哥-拉蒙-卡亚尔在19世纪末提出的。它认为，神经元是离散的细胞（不以网状结构连接），作为新陈代谢的不同单位发挥作用。
Later discoveries yielded refinements to the doctrine. For example, [[Neuroglia|glial cells]], which are non-neuronal, play an essential role in information processing.<ref>{{cite journal | vauthors = Witcher MR, Kirov SA, Harris KM | title = Plasticity of perisynaptic astroglia during synaptogenesis in the mature rat hippocampus | journal = Glia | volume = 55 | issue = 1 | pages = 13–23 | date = January 2007 | pmid = 17001633 | doi = 10.1002/glia.20415 | citeseerx = 10.1.1.598.7002 | s2cid = 10664003 }}</ref> Also, electrical synapses are more common than previously thought,<ref>{{cite journal | vauthors = Connors BW, Long MA | title = Electrical synapses in the mammalian brain | journal = Annual Review of Neuroscience | volume = 27 | issue = 1 | pages = 393–418 | year = 2004 | pmid = 15217338 | doi = 10.1146/annurev.neuro.26.041002.131128 | url = https://zenodo.org/record/894386 }}</ref> comprising direct, cytoplasmic connections between neurons. In fact, neurons can form even tighter couplings: the squid giant axon arises from the fusion of multiple axons.<ref>{{cite journal | vauthors = Guillery RW | title = Observations of synaptic structures: origins of the neuron doctrine and its current status | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 360 | issue = 1458 | pages = 1281–307 | date = June 2005 | pmid = 16147523 | pmc = 1569502 | doi = 10.1098/rstb.2003.1459 }}</ref>
Later discoveries yielded refinements to the doctrine. For example, [[Neuroglia|glial cells]], which are non-neuronal, play an essential role in information processing.<ref>{{cite journal | vauthors = Witcher MR, Kirov SA, Harris KM | title = Plasticity of perisynaptic astroglia during synaptogenesis in the mature rat hippocampus | journal = Glia | volume = 55 | issue = 1 | pages = 13–23 | date = January 2007 | pmid = 17001633 | doi = 10.1002/glia.20415 | citeseerx = 10.1.1.598.7002 | s2cid = 10664003 }}</ref> Also, electrical synapses are more common than previously thought,<ref>{{cite journal | vauthors = Connors BW, Long MA | title = Electrical synapses in the mammalian brain | journal = Annual Review of Neuroscience | volume = 27 | issue = 1 | pages = 393–418 | year = 2004 | pmid = 15217338 | doi = 10.1146/annurev.neuro.26.041002.131128 | url = https://zenodo.org/record/894386 }}</ref> comprising direct, cytoplasmic connections between neurons. In fact, neurons can form even tighter couplings: the squid giant axon arises from the fusion of multiple axons.<ref>{{cite journal | vauthors = Guillery RW | title = Observations of synaptic structures: origins of the neuron doctrine and its current status | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 360 | issue = 1458 | pages = 1281–307 | date = June 2005 | pmid = 16147523 | pmc = 1569502 | doi = 10.1098/rstb.2003.1459 }}</ref>
后来的发现使这一学说得到了完善。例如，非神经元的胶质细胞在信息处理中起着至关重要的作用。[44] 另外，电突触比以前认为得更常见，[45] 包括神经元之间的直接胞质连接。事实上，神经元可以形成更紧密的耦合：乌贼的巨型轴突来自于多个轴突的融合。[46]
Ramón y Cajal also postulated the Law of Dynamic Polarization, which states that a neuron receives signals at its dendrites and cell body and transmits them, as action potentials, along the axon in one direction: away from the cell body.<ref name="sabb">{{cite journal | vauthors = Sabbatini RM | date = April–July 2003 | url = http://www.cerebromente.org.br/n17/history/neurons3_i.htm | title = Neurons and Synapses: The History of Its Discovery | journal = Brain & Mind Magazine | pages = 17 }}</ref> The Law of Dynamic Polarization has important exceptions; dendrites can serve as synaptic output sites of neurons<ref>{{cite journal | vauthors = Djurisic M, Antic S, Chen WR, Zecevic D | title = Voltage imaging from dendrites of mitral cells: EPSP attenuation and spike trigger zones | journal = The Journal of Neuroscience | volume = 24 | issue = 30 | pages = 6703–14 | date = July 2004 | pmid = 15282273 | pmc = 6729725 | doi = 10.1523/JNEUROSCI.0307-04.2004 | hdl = 1912/2958 }}
Ramón y Cajal also postulated the Law of Dynamic Polarization, which states that a neuron receives signals at its dendrites and cell body and transmits them, as action potentials, along the axon in one direction: away from the cell body.<ref name="sabb">{{cite journal | vauthors = Sabbatini RM | date = April–July 2003 | url = http://www.cerebromente.org.br/n17/history/neurons3_i.htm | title = Neurons and Synapses: The History of Its Discovery | journal = Brain & Mind Magazine | pages = 17 }}</ref> The Law of Dynamic Polarization has important exceptions; dendrites can serve as synaptic output sites of neurons<ref>{{cite journal | vauthors = Djurisic M, Antic S, Chen WR, Zecevic D | title = Voltage imaging from dendrites of mitral cells: EPSP attenuation and spike trigger zones | journal = The Journal of Neuroscience | volume = 24 | issue = 30 | pages = 6703–14 | date = July 2004 | pmid = 15282273 | pmc = 6729725 | doi = 10.1523/JNEUROSCI.0307-04.2004 | hdl = 1912/2958 }}
</ref> and axons can receive synaptic inputs.<ref>{{cite journal | vauthors = Cochilla AJ, Alford S | title = Glutamate receptor-mediated synaptic excitation in axons of the lamprey | journal = The Journal of Physiology | volume = 499 | issue = Pt 2 | pages = 443–57 | date = March 1997 | pmid = 9080373 | pmc = 1159318 | doi = 10.1113/jphysiol.1997.sp021940 }}</ref>
</ref> and axons can receive synaptic inputs.<ref>{{cite journal | vauthors = Cochilla AJ, Alford S | title = Glutamate receptor-mediated synaptic excitation in axons of the lamprey | journal = The Journal of Physiology | volume = 499 | issue = Pt 2 | pages = 443–57 | date = March 1997 | pmid = 9080373 | pmc = 1159318 | doi = 10.1113/jphysiol.1997.sp021940 }}</ref>
拉蒙-卡哈尔还提出了动态极化定律，即神经元在其树突和细胞体上接收信号，并作为动作电位沿轴突向一个方向传输：离开细胞体。[47] 动态极化定律有重要的例外；树突可以作为神经元的突触输出点[48] ，轴突可以接受突触输入。[49]
===Compartmental modelling of neurons 神经元的间室模型===
Although neurons are often described of as "fundamental units" of the brain, they perform internal computations. Neurons integrate input within dendrites, and this complexity is lost in models that assume neurons to be a fundamental unit. Dendritic branches can be modeled as spatial compartments, whose activity is related due to passive membrane properties, but may also be different depending on input from synapses. [[Compartmental modelling of dendrites]] is especially helpful for understanding the behavior of neurons that are too small to record with electrodes, as is the case for ''Drosophila melanogaster''.<ref>{{cite journal | vauthors = Gouwens NW, Wilson RI | title = Signal propagation in Drosophila central neurons | journal = Journal of Neuroscience | volume = 29 | issue = 19 | pages = 6239–6249 | year = 2009 | pmid = 19439602 | pmc = 2709801 | doi = 10.1523/jneurosci.0764-09.2009 | doi-access = free }}</ref>
Although neurons are often described of as "fundamental units" of the brain, they perform internal computations. Neurons integrate input within dendrites, and this complexity is lost in models that assume neurons to be a fundamental unit. Dendritic branches can be modeled as spatial compartments, whose activity is related due to passive membrane properties, but may also be different depending on input from synapses. [[Compartmental modelling of dendrites]] is especially helpful for understanding the behavior of neurons that are too small to record with electrodes, as is the case for ''Drosophila melanogaster''.<ref>{{cite journal | vauthors = Gouwens NW, Wilson RI | title = Signal propagation in Drosophila central neurons | journal = Journal of Neuroscience | volume = 29 | issue = 19 | pages = 6239–6249 | year = 2009 | pmid = 19439602 | pmc = 2709801 | doi = 10.1523/jneurosci.0764-09.2009 | doi-access = free }}</ref>
尽管神经元经常被描述为大脑的 "基本单位"，但它们执行内部计算。神经元在树突内整合输入，这种复杂性在假定神经元是一个基本单位的模型中丢失。树突分支可以被建模为空间隔间，其活性与被动膜特性相关，但也可能因来自突触的输入的差异而有所不同。树突的间室模型对于理解那些太小而无法用电极记录的神经元的行为特别有帮助，黑腹果蝇就是这种情况。[50]
= = = = 神经元的分室模型虽然神经元常常被描述为大脑的“基本单位”，但它们执行内部计算。神经元整合树突内的输入，这种复杂性在假定神经元是基本单位的模型中丢失了。树突状分支可以被模拟为空间隔室，其活动与被动膜特性有关，但也可能因突触输入的不同而有所不同。树突的分室模型特别有助于理解神经元的行为，因为神经元太小，不能用电极记录，就像黑腹果蝇的情况一样。
==Neurons in the brain大脑中的神经元==
The number of neurons in the brain varies dramatically from species to species.<ref name="nervenet">{{cite journal | vauthors = Williams RW, Herrup K | title = The control of neuron number | journal = Annual Review of Neuroscience | volume = 11 | issue = 1 | pages = 423–53 | year = 1988 | pmid = 3284447 | doi = 10.1146/annurev.ne.11.030188.002231 }}</ref> In a human, there are an estimated 10–20 billion neurons in the [[cerebral cortex]]<!--<ref name="pmid27187682" />--> and 55–70 billion neurons in the [[cerebellum]].<ref name="pmid27187682">{{cite journal | vauthors = von Bartheld CS, Bahney J, Herculano-Houzel S | title = The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting | journal = The Journal of Comparative Neurology | volume = 524 | issue = 18 | pages = 3865–3895 | date = December 2016 | pmid = 27187682 | pmc = 5063692 | doi = 10.1002/cne.24040 }}</ref> By contrast, the [[nematode]] worm ''[[Caenorhabditis elegans]]'' has just 302 neurons, making it an ideal [[model organism]] as scientists have been able to map all of its neurons. The fruit fly ''[[Drosophila melanogaster]]'', a common subject in biological experiments, has around 100,000 neurons and exhibits many complex behaviors. Many properties of neurons, from the type of neurotransmitters used to ion channel composition, are maintained across species, allowing scientists to study processes occurring in more complex organisms in much simpler experimental systems.
The number of neurons in the brain varies dramatically from species to species.<ref name="nervenet">{{cite journal | vauthors = Williams RW, Herrup K | title = The control of neuron number | journal = Annual Review of Neuroscience | volume = 11 | issue = 1 | pages = 423–53 | year = 1988 | pmid = 3284447 | doi = 10.1146/annurev.ne.11.030188.002231 }}</ref> In a human, there are an estimated 10–20 billion neurons in the [[cerebral cortex]]<!--<ref name="pmid27187682" />--> and 55–70 billion neurons in the [[cerebellum]].<ref name="pmid27187682">{{cite journal | vauthors = von Bartheld CS, Bahney J, Herculano-Houzel S | title = The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting | journal = The Journal of Comparative Neurology | volume = 524 | issue = 18 | pages = 3865–3895 | date = December 2016 | pmid = 27187682 | pmc = 5063692 | doi = 10.1002/cne.24040 }}</ref> By contrast, the [[nematode]] worm ''[[Caenorhabditis elegans]]'' has just 302 neurons, making it an ideal [[model organism]] as scientists have been able to map all of its neurons. The fruit fly ''[[Drosophila melanogaster]]'', a common subject in biological experiments, has around 100,000 neurons and exhibits many complex behaviors. Many properties of neurons, from the type of neurotransmitters used to ion channel composition, are maintained across species, allowing scientists to study processes occurring in more complex organisms in much simpler experimental systems.
大脑中的神经元数量因物种不同而有很大差异。[51] 在人类中，大脑皮层中估计有100-200亿个神经元，小脑中有550-700亿个神经元。[52] 相比之下，秀丽隐杆线虫只有302个神经元，使其成为理想的模型生物，因为科学家已经能够绘制其所有的神经元。黑腹果蝇是生物实验中常见的对象，它有大约10万个神经元，表现出许多复杂的行为。神经元的许多特性，从使用的神经递质类型到离子通道组成，在不同的物种中都保持不变，使科学家能够在更简单的实验系统中研究发生在更复杂生物体中的过程。
= = 大脑中的神经元 = = 大脑中神经元的数量因物种而异。据估计，人类大脑皮层中有100-200亿个神经元，小脑中有550-700亿个神经元。相比之下，线虫秀丽隐桿线虫只有302个神经元，这使它成为一个理想的模式生物，因为科学家已经能够绘制它所有的神经元。果蝇黑腹果蝇是生物学实验中的常见实验对象，它有大约10万个神经元，表现出许多复杂的行为。神经元的许多特性，从神经递质的类型到离子通道的组成，跨物种保持，使科学家能够在更简单的实验系统中研究更复杂的生物体中发生的过程。
==Neurological disorders神经系统疾病==
{{Main主要文章|Neurology神经病学}}
{{More citations needed|date=May 2018}}
'''[[Charcot–Marie–Tooth disease]]''' (CMT) is a heterogeneous inherited disorder of nerves ([[neuropathy]]) that is characterized by loss of muscle tissue and touch sensation, predominantly in the feet and legs extending to the hands and arms in advanced stages. Presently incurable, this disease is one of the most common inherited neurological disorders, with 36 in 100,000 affected.<ref name=Krajewski>{{cite journal | vauthors = Krajewski KM, Lewis RA, Fuerst DR, Turansky C, Hinderer SR, Garbern J, Kamholz J, Shy ME | title = Neurological dysfunction and axonal degeneration in Charcot-Marie-Tooth disease type 1A | journal = Brain | volume = 123 | issue = 7 | pages = 1516–27 | date = July 2000 | pmid = 10869062 | doi = 10.1093/brain/123.7.1516 | doi-access = free }}</ref>
'''[[Charcot–Marie–Tooth disease]]''' (CMT) is a heterogeneous inherited disorder of nerves ([[neuropathy]]) that is characterized by loss of muscle tissue and touch sensation, predominantly in the feet and legs extending to the hands and arms in advanced stages. Presently incurable, this disease is one of the most common inherited neurological disorders, with 36 in 100,000 affected.<ref name=Krajewski>{{cite journal | vauthors = Krajewski KM, Lewis RA, Fuerst DR, Turansky C, Hinderer SR, Garbern J, Kamholz J, Shy ME | title = Neurological dysfunction and axonal degeneration in Charcot-Marie-Tooth disease type 1A | journal = Brain | volume = 123 | issue = 7 | pages = 1516–27 | date = July 2000 | pmid = 10869062 | doi = 10.1093/brain/123.7.1516 | doi-access = free }}</ref>
腓骨肌萎缩症 （CMT）是一种异质性的遗传性神经疾病（神经病变），其特点是肌肉组织和触觉的丧失，主要是在脚和腿上，在晚期会延伸到手和胳膊。该病目前无法治愈，是最常见的遗传性神经系统疾病之一，每10万人中会有36人罹患此病。[53]
'''[[Alzheimer's disease]]''' (AD), also known simply as ''Alzheimer's'', is a [[neurodegenerative disease]] characterized by progressive [[cognitive]] deterioration, together with declining activities of daily living and [[neuropsychiatric]] symptoms or behavioral changes.<ref name="nihstages">{{cite web|title=About Alzheimer's Disease: Symptoms|url=http://www.nia.nih.gov/alzheimers/topics/symptoms|publisher=National Institute on Aging|access-date=28 December 2011|url-status=live|archive-url=https://web.archive.org/web/20120115201854/http://www.nia.nih.gov/alzheimers/topics/symptoms|archive-date=15 January 2012|df=dmy-all}}</ref> The most striking early symptom is loss of short-term memory ([[amnesia]]), which usually manifests as minor forgetfulness that becomes steadily more pronounced with illness progression, with relative preservation of older memories. As the disorder progresses, cognitive (intellectual) impairment extends to the domains of language ([[aphasia]]), skilled movements ([[apraxia]]), and recognition ([[agnosia]]), and functions such as decision-making and planning become impaired.<ref name="BMJ2009">{{cite journal | vauthors = Burns A, Iliffe S | title = Alzheimer's disease | journal = BMJ | volume = 338 | pages = b158 | date = February 2009 | pmid = 19196745 | doi = 10.1136/bmj.b158 | s2cid = 8570146 | url = https://semanticscholar.org/paper/0fccf0616b35e3bb427c3783a44777e4dc228713 }}</ref><ref name=NEJM2010>{{cite journal | vauthors = Querfurth HW, LaFerla FM | title = Alzheimer's disease | journal = The New England Journal of Medicine | volume = 362 | issue = 4 | pages = 329–44 | date = January 2010 | pmid = 20107219 | doi = 10.1056/NEJMra0909142 | s2cid = 205115756 | url = https://semanticscholar.org/paper/7bc445c5ddf7869b9f71a5390ff9e9e992533ee3 }}</ref>
'''[[Alzheimer's disease]]''' (AD), also known simply as ''Alzheimer's'', is a [[neurodegenerative disease]] characterized by progressive [[cognitive]] deterioration, together with declining activities of daily living and [[neuropsychiatric]] symptoms or behavioral changes.<ref name="nihstages">{{cite web|title=About Alzheimer's Disease: Symptoms|url=http://www.nia.nih.gov/alzheimers/topics/symptoms|publisher=National Institute on Aging|access-date=28 December 2011|url-status=live|archive-url=https://web.archive.org/web/20120115201854/http://www.nia.nih.gov/alzheimers/topics/symptoms|archive-date=15 January 2012|df=dmy-all}}</ref> The most striking early symptom is loss of short-term memory ([[amnesia]]), which usually manifests as minor forgetfulness that becomes steadily more pronounced with illness progression, with relative preservation of older memories. As the disorder progresses, cognitive (intellectual) impairment extends to the domains of language ([[aphasia]]), skilled movements ([[apraxia]]), and recognition ([[agnosia]]), and functions such as decision-making and planning become impaired.<ref name="BMJ2009">{{cite journal | vauthors = Burns A, Iliffe S | title = Alzheimer's disease | journal = BMJ | volume = 338 | pages = b158 | date = February 2009 | pmid = 19196745 | doi = 10.1136/bmj.b158 | s2cid = 8570146 | url = https://semanticscholar.org/paper/0fccf0616b35e3bb427c3783a44777e4dc228713 }}</ref><ref name=NEJM2010>{{cite journal | vauthors = Querfurth HW, LaFerla FM | title = Alzheimer's disease | journal = The New England Journal of Medicine | volume = 362 | issue = 4 | pages = 329–44 | date = January 2010 | pmid = 20107219 | doi = 10.1056/NEJMra0909142 | s2cid = 205115756 | url = https://semanticscholar.org/paper/7bc445c5ddf7869b9f71a5390ff9e9e992533ee3 }}</ref>
阿尔茨海默病（AD），也被简单地称为阿尔茨海默病，是一种神经退行性疾病，其特点是认知能力逐渐退化，伴随着日常生活活动能力下降和神经精神症状或行为变化。[54] 最突出的早期症状是短期记忆的丧失（失忆），通常表现为轻微的遗忘，随着病情的发展，遗忘的程度会逐渐加重，但老的记忆却记忆得相对清楚。随着病情的发展，认知（智力）损害扩展到语言（失语）、熟练动作（失用）和识别（失认）等领域，决策和计划等功能也会受到损害[55][56] 。
'''[[Parkinson's disease]]''' (PD), also known as ''Parkinson disease'', is a degenerative disorder of the central nervous system that often impairs motor skills and speech.<ref name=NIH2016>{{cite web|title=Parkinson's Disease Information Page|url=https://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page|website=NINDS|access-date=18 July 2016|date=30 June 2016|url-status=live|archive-url=https://web.archive.org/web/20170104201403/http://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page|archive-date=4 January 2017|df=dmy-all}}</ref> Parkinson's disease belongs to a group of conditions called [[movement disorders]].<ref>{{cite web | title = Movement Disorders| url = http://www.neuromodulation.com/movement-disorders | work = The International Neuromodulation Society }}</ref> It is characterized by muscle rigidity, [[tremor]], a slowing of physical movement ([[bradykinesia]]), and in extreme cases, a loss of physical movement ([[akinesia]]). The primary symptoms are the results of decreased stimulation of the [[motor cortex]] by the [[basal ganglia]], normally caused by the insufficient formation and action of dopamine, which is produced in the dopaminergic neurons of the brain. Secondary symptoms may include high level [[cognitive dysfunction]] and subtle language problems. PD is both chronic and progressive.
'''[[Parkinson's disease]]''' (PD), also known as ''Parkinson disease'', is a degenerative disorder of the central nervous system that often impairs motor skills and speech.<ref name=NIH2016>{{cite web|title=Parkinson's Disease Information Page|url=https://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page|website=NINDS|access-date=18 July 2016|date=30 June 2016|url-status=live|archive-url=https://web.archive.org/web/20170104201403/http://www.ninds.nih.gov/Disorders/All-Disorders/Parkinsons-Disease-Information-Page|archive-date=4 January 2017|df=dmy-all}}</ref> Parkinson's disease belongs to a group of conditions called [[movement disorders]].<ref>{{cite web | title = Movement Disorders| url = http://www.neuromodulation.com/movement-disorders | work = The International Neuromodulation Society }}</ref> It is characterized by muscle rigidity, [[tremor]], a slowing of physical movement ([[bradykinesia]]), and in extreme cases, a loss of physical movement ([[akinesia]]). The primary symptoms are the results of decreased stimulation of the [[motor cortex]] by the [[basal ganglia]], normally caused by the insufficient formation and action of dopamine, which is produced in the dopaminergic neurons of the brain. Secondary symptoms may include high level [[cognitive dysfunction]] and subtle language problems. PD is both chronic and progressive.
帕金森病（PD），又称帕金森病，是一种中枢神经系统的退行性疾病，通常会损害运动技能和语言能力。[57] 帕金森病属于一组被称为运动障碍的疾病。[58] 它的特点是肌肉僵硬、震颤、身体运动变慢（运动迟缓），在极端情况下，身体运动丧失（运动不能）。主要症状是基底神经节对运动皮层刺激减少的结果，通常是由于大脑多巴胺能神经元中产生的多巴胺形成和作用不足造成的。次要症状可能包括高水平的认知功能障碍和微妙的语言问题。帕金森病既是慢性的，也是渐进的。
'''[[Myasthenia gravis]]''' is a neuromuscular disease leading to fluctuating [[muscle weakness]] and fatigability during simple activities. Weakness is typically caused by circulating [[antibodies]] that block [[acetylcholine receptors]] at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine. Myasthenia is treated with [[immunosuppressants]], [[cholinesterase]] inhibitors and, in selected cases, [[thymectomy]].
'''[[Myasthenia gravis]]''' is a neuromuscular disease leading to fluctuating [[muscle weakness]] and fatigability during simple activities. Weakness is typically caused by circulating [[antibodies]] that block [[acetylcholine receptors]] at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine. Myasthenia is treated with [[immunosuppressants]], [[cholinesterase]] inhibitors and, in selected cases, [[thymectomy]].
重症肌无力是一种神经肌肉疾病，导致简单活动时出现波动性的肌肉无力和疲劳。肌无力通常是由阻断突触后神经肌肉接头处的乙酰胆碱受体的循环抗体引起的，它抑制了神经递质乙酰胆碱的刺激作用。肌无力症用免疫抑制剂、胆碱酯酶抑制剂来治疗，在某些情况下还可以进行胸腺切除术。
===Demyelination脱髓鞘症===
{{Further|Demyelinating disease}}
[[File:Guillain-barré syndrome - Nerve Damage.gif|thumb|Guillain–Barré syndrome – demyelination格林-巴利综合征——脱髓鞘症]]
[[Demyelination]] is the act of demyelinating, or the loss of the myelin sheath insulating the nerves. When myelin degrades, conduction of signals along the nerve can be impaired or lost, and the nerve eventually withers. This leads to certain neurodegenerative disorders like [[multiple sclerosis]] and [[chronic inflammatory demyelinating polyneuropathy]].
[[Demyelination]] is the act of demyelinating, or the loss of the myelin sheath insulating the nerves. When myelin degrades, conduction of signals along the nerve can be impaired or lost, and the nerve eventually withers. This leads to certain neurodegenerative disorders like [[multiple sclerosis]] and [[chronic inflammatory demyelinating polyneuropathy]].
脱髓鞘是指脱髓鞘的行为，或绝缘于神经的髓鞘的丧失。当髓鞘退化时，信号沿神经的传导会受到影响或丧失，神经最终会萎缩。这导致了某些神经退行性疾病，如多发性硬化症和慢性炎症性脱髓鞘多发性神经病。
===Axonal degeneration轴突变性===
===Axonal degeneration===
Although most injury responses include a calcium influx signaling to promote resealing of severed parts, axonal injuries initially lead to acute axonal degeneration, which is the rapid separation of the proximal and distal ends, occurring within 30 minutes of injury. Degeneration follows with swelling of the [[axolemma]], and eventually leads to bead-like formation. Granular disintegration of the axonal [[cytoskeleton]] and inner [[organelle]]s occurs after axolemma degradation. Early changes include accumulation of [[mitochondria]] in the paranodal regions at the site of injury. Endoplasmic reticulum degrades and mitochondria swell up and eventually disintegrate. The disintegration is dependent on [[ubiquitin]] and [[calpain]] [[proteases]] (caused by the influx of calcium ion), suggesting that axonal degeneration is an active process that produces complete fragmentation. The process takes about roughly 24 hours in the PNS and longer in the CNS. The signaling pathways leading to axolemma degeneration are unknown.
Although most injury responses include a calcium influx signaling to promote resealing of severed parts, axonal injuries initially lead to acute axonal degeneration, which is the rapid separation of the proximal and distal ends, occurring within 30 minutes of injury. Degeneration follows with swelling of the [[axolemma]], and eventually leads to bead-like formation. Granular disintegration of the axonal [[cytoskeleton]] and inner [[organelle]]s occurs after axolemma degradation. Early changes include accumulation of [[mitochondria]] in the paranodal regions at the site of injury. Endoplasmic reticulum degrades and mitochondria swell up and eventually disintegrate. The disintegration is dependent on [[ubiquitin]] and [[calpain]] [[proteases]] (caused by the influx of calcium ion), suggesting that axonal degeneration is an active process that produces complete fragmentation. The process takes about roughly 24 hours in the PNS and longer in the CNS. The signaling pathways leading to axolemma degeneration are unknown.
尽管大多数损伤反应包括钙离子流入信号，以促进断裂部分的重新愈合，但轴突损伤最初会导致急性轴突变性，即在损伤后30分钟内近端和远端迅速分离。退化后，轴突肿胀，最终形成串珠状肿胀。轴索细胞骨架和内部细胞器的颗粒状解体发生在轴索退化之后。早期的变化包括线粒体在损伤部位的结旁区堆积。内质网降解、线粒体膨胀并最终解体。解体依赖于泛素和钙蛋白酶（由钙离子的涌入引起），表明轴突变性是一个完全破碎的活跃过程。这一过程在PNS（周围神经系统）中大约需要24小时，在CNS（中枢神经系统）中则需要更长时间。导致轴突变性的信号传导途径尚不清楚。
==Neurogenesis神经发生==
{{Main|Neurogenesis}}
Neurons are born through the process of [[neurogenesis]], in which [[neural stem cell]]s divide to produce differentiated neurons. Once fully differentiated neurons are formed, they are no longer capable of undergoing [[mitosis]]. Neurogenesis primarily occurs in the embryo of most organisms.
Neurons are born through the process of [[neurogenesis]], in which [[neural stem cell]]s divide to produce differentiated neurons. Once fully differentiated neurons are formed, they are no longer capable of undergoing [[mitosis]]. Neurogenesis primarily occurs in the embryo of most organisms.
神经元是通过神经发生的过程诞生的，其中神经干细胞分裂产生分化的神经元。一旦完全分化的神经元形成，它们就不再能够进行有丝分裂。神经发生主要发生在大多数生物体的胚胎中。
[[Adult neurogenesis]] can occur and studies of the age of human neurons suggest that this process occurs only for a minority of cells, and that the vast majority of neurons in the [[neocortex]] forms before birth and persists without replacement. The extent to which adult neurogenesis exists in humans, and its contribution to cognition are controversial, with conflicting reports published in 2018.<ref>{{cite journal | vauthors = Kempermann G, Gage FH, Aigner L, Song H, Curtis MA, Thuret S, Kuhn HG, Jessberger S, Frankland PW, Cameron HA, Gould E, Hen R, Abrous DN, Toni N, Schinder AF, Zhao X, Lucassen PJ, Frisén J | title = Human Adult Neurogenesis: Evidence and Remaining Questions | journal = Cell Stem Cell | volume = 23 | issue = 1 | pages = 25–30 | date = July 2018 | pmid = 29681514 | pmc = 6035081 | doi = 10.1016/j.stem.2018.04.004 }}</ref>
[[Adult neurogenesis]] can occur and studies of the age of human neurons suggest that this process occurs only for a minority of cells, and that the vast majority of neurons in the [[neocortex]] forms before birth and persists without replacement. The extent to which adult neurogenesis exists in humans, and its contribution to cognition are controversial, with conflicting reports published in 2018.<ref>{{cite journal | vauthors = Kempermann G, Gage FH, Aigner L, Song H, Curtis MA, Thuret S, Kuhn HG, Jessberger S, Frankland PW, Cameron HA, Gould E, Hen R, Abrous DN, Toni N, Schinder AF, Zhao X, Lucassen PJ, Frisén J | title = Human Adult Neurogenesis: Evidence and Remaining Questions | journal = Cell Stem Cell | volume = 23 | issue = 1 | pages = 25–30 | date = July 2018 | pmid = 29681514 | pmc = 6035081 | doi = 10.1016/j.stem.2018.04.004 }}</ref>
成年神经发生能够发生，对人类神经元年龄的研究表明，这一过程只发生在少数细胞中，新皮层中的绝大多数神经元在出生前就已形成，并持续存在而不被替换。人类中成年神经发生存在的程度，以及它对认知的贡献是有争议的，2018年发表的报告相互矛盾。[59]
The body contains a variety of stem cell types that have the capacity to differentiate into neurons. Researchers found a way to transform human skin cells into nerve cells using [[transdifferentiation]], in which "cells are forced to adopt new identities".<ref name=twsX33>{{Cite journal |doi=10.1038/news.2011.328 | last = Callaway | first = Ewen |title= How to make a human neuron | journal = Nature |quote= By transforming cells from human skin into working nerve cells, researchers may have come up with a model for nervous-system diseases and perhaps even regenerative therapies based on cell transplants. The achievement, reported online today in ''Nature'', is the latest in a fast-moving field called transdifferentiation, in which cells are forced to adopt new identities. In the past year, researchers have converted connective tissue cells found in skin into heart cells, blood cells, and liver cells.
The body contains a variety of stem cell types that have the capacity to differentiate into neurons. Researchers found a way to transform human skin cells into nerve cells using [[transdifferentiation]], in which "cells are forced to adopt new identities".<ref name=twsX33>{{Cite journal |doi=10.1038/news.2011.328 | last = Callaway | first = Ewen |title= How to make a human neuron | journal = Nature |quote= By transforming cells from human skin into working nerve cells, researchers may have come up with a model for nervous-system diseases and perhaps even regenerative therapies based on cell transplants. The achievement, reported online today in ''Nature'', is the latest in a fast-moving field called transdifferentiation, in which cells are forced to adopt new identities. In the past year, researchers have converted connective tissue cells found in skin into heart cells, blood cells, and liver cells.
|date= 26 May 2011 }}</ref>
|date= 26 May 2011 }}</ref>
人体含有各种干细胞类型，它们有能力分化为神经元。研究人员发现了一种利用横向分化将人类皮肤细胞转化为神经细胞的方法，其中 "细胞被迫采用新的身份"。[60]
During [[neurogenesis]] in the mammalian brain, progenitor and stem cells progress from proliferative divisions to differentiative divisions. This progression leads to the neurons and glia that populate cortical layers. [[Epigenetics|Epigenetic]] modifications play a key role in regulating [[gene expression]] in differentiating [[neural stem cells]], and are critical for cell fate determination in the developing and adult mammalian brain. Epigenetic modifications include [[DNA methylation|DNA cytosine methylation]] to form [[5-methylcytosine]] and [[DNA demethylation|5-methylcytosine demethylation]].<ref name=Wang2016>{{cite journal | vauthors = Wang Z, Tang B, He Y, Jin P | title = DNA methylation dynamics in neurogenesis | journal = Epigenomics | volume = 8 | issue = 3 | pages = 401–14 | date = March 2016 | pmid = 26950681 | pmc = 4864063 | doi = 10.2217/epi.15.119 }}</ref> These modifications are critical for cell fate determination in the developing and adult mammalian brain. [[DNA methylation|DNA cytosine methylation]] is catalyzed by [[DNA methyltransferase|DNA methyltransferases (DNMTs)]]. Methylcytosine demethylation is catalyzed in several stages by [[TET enzymes]] that carry out oxidative reactions (e.g. [[5-methylcytosine]] to [[5-hydroxymethylcytosine]]) and enzymes of the DNA [[base excision repair]] (BER) pathway.<ref name=Wang2016/>
During [[neurogenesis]] in the mammalian brain, progenitor and stem cells progress from proliferative divisions to differentiative divisions. This progression leads to the neurons and glia that populate cortical layers. [[Epigenetics|Epigenetic]] modifications play a key role in regulating [[gene expression]] in differentiating [[neural stem cells]], and are critical for cell fate determination in the developing and adult mammalian brain. Epigenetic modifications include [[DNA methylation|DNA cytosine methylation]] to form [[5-methylcytosine]] and [[DNA demethylation|5-methylcytosine demethylation]].<ref name=Wang2016>{{cite journal | vauthors = Wang Z, Tang B, He Y, Jin P | title = DNA methylation dynamics in neurogenesis | journal = Epigenomics | volume = 8 | issue = 3 | pages = 401–14 | date = March 2016 | pmid = 26950681 | pmc = 4864063 | doi = 10.2217/epi.15.119 }}</ref> These modifications are critical for cell fate determination in the developing and adult mammalian brain. [[DNA methylation|DNA cytosine methylation]] is catalyzed by [[DNA methyltransferase|DNA methyltransferases (DNMTs)]]. Methylcytosine demethylation is catalyzed in several stages by [[TET enzymes]] that carry out oxidative reactions (e.g. [[5-methylcytosine]] to [[5-hydroxymethylcytosine]]) and enzymes of the DNA [[base excision repair]] (BER) pathway.<ref name=Wang2016/>
在哺乳动物大脑的神经发生过程中，祖细胞和干细胞从增殖性分裂发展到分化性分裂。这一进展导致了皮层中的神经元和胶质细胞的出现。表观遗传学修饰在调节分化中的神经干细胞的基因表达方面起着关键作用，对发育中和成年哺乳动物大脑中的细胞命运决定至关重要。表观遗传修饰包括DNA胞嘧啶甲基化形成5-甲基胞嘧啶和5-甲基胞嘧啶去甲基化。[61] 这些修饰对于发育中和成年哺乳动物大脑的细胞命运决定至关重要。DNA胞嘧啶甲基化是由DNA甲基转移酶（DNMTs）催化的。甲基胞嘧啶去甲基化是由进行氧化反应（如5-甲基胞嘧啶到5-羟甲基胞嘧啶）的TET酶和DNA碱基切除修复（BER）途径的酶分几个阶段催化的[61] 。
At different stages of mammalian nervous system development two DNA repair processes are employed in the repair of DNA double-strand breaks. These pathways are [[homologous recombination]]al repair used in proliferating neural precursor cells, and [[non-homologous end joining]] used mainly at later developmental stages<ref>{{cite journal | vauthors = Orii KE, Lee Y, Kondo N, McKinnon PJ | title = Selective utilization of nonhomologous end-joining and homologous recombination DNA repair pathways during nervous system development | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 103 | issue = 26 | pages = 10017–22 | date = June 2006 | pmid = 16777961 | pmc = 1502498 | doi = 10.1073/pnas.0602436103 | bibcode = 2006PNAS..10310017O | doi-access = free }}</ref>
At different stages of mammalian nervous system development two DNA repair processes are employed in the repair of DNA double-strand breaks. These pathways are [[homologous recombination]]al repair used in proliferating neural precursor cells, and [[non-homologous end joining]] used mainly at later developmental stages<ref>{{cite journal | vauthors = Orii KE, Lee Y, Kondo N, McKinnon PJ | title = Selective utilization of nonhomologous end-joining and homologous recombination DNA repair pathways during nervous system development | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 103 | issue = 26 | pages = 10017–22 | date = June 2006 | pmid = 16777961 | pmc = 1502498 | doi = 10.1073/pnas.0602436103 | bibcode = 2006PNAS..10310017O | doi-access = free }}</ref>
在哺乳动物神经系统发育的不同阶段，有两种DNA修复过程被用于修复DNA双链断裂。这些途径是用于增殖期神经前体细胞的同源重组修复，以及主要用于后期发育阶段的非同源末端连接[62] 。
==Nerve regeneration神经再生==
== Nerve regeneration ==
{{Main|Neuroregeneration}}
{{Main|Neuroregeneration}}
Peripheral axons can regrow if they are severed,<ref name="Yiu_2006">{{cite journal | vauthors = Yiu G, He Z | title = Glial inhibition of CNS axon regeneration | journal = Nature Reviews. Neuroscience | volume = 7 | issue = 8 | pages = 617–27 | date = August 2006 | pmid = 16858390 | pmc = 2693386 | doi = 10.1038/nrn1956 }}</ref> but one neuron cannot be functionally replaced by one of another type ([[Llinás' law]]).<ref name="llinas2014"/>
Peripheral axons can regrow if they are severed,<ref name="Yiu_2006">{{cite journal | vauthors = Yiu G, He Z | title = Glial inhibition of CNS axon regeneration | journal = Nature Reviews. Neuroscience | volume = 7 | issue = 8 | pages = 617–27 | date = August 2006 | pmid = 16858390 | pmc = 2693386 | doi = 10.1038/nrn1956 }}</ref> but one neuron cannot be functionally replaced by one of another type ([[Llinás' law]]).<ref name="llinas2014"/>
外围轴突如果被切断，可以重新生长，[63]但一个神经元在功能上不能被另一种类型的神经元取代（Llinás法则）[15]。
== See also ==
== See also ==
{{Div col end}}
{{Div col end}}
*人工神经元
*双向细胞
*生物神经元模型
*间室神经元模型
*连接组
*锥体细胞
*按神经元数量排列的动物名单
*神经科学数据库列表
*神经元向电性
*神经可塑性
*生长锥
*肖尔分析
== References参考文献 ==
== References ==
{{Reflist}}
{{Reflist}}
== Further reading ==
== Further reading进一步阅读 ==
{{refbegin}}
{{refbegin}}
* {{cite journal | vauthors = Bullock TH, Bennett MV, Johnston D, Josephson R, Marder E, Fields RD | title = Neuroscience. The neuron doctrine, redux | journal = Science | volume = 310 | issue = 5749 | pages = 791–3 | date = November 2005 | pmid = 16272104 | doi = 10.1126/science.1114394 | s2cid = 170670241 }}
* {{cite journal | vauthors = Bullock TH, Bennett MV, Johnston D, Josephson R, Marder E, Fields RD | title = Neuroscience. The neuron doctrine, redux | journal = Science | volume = 310 | issue = 5749 | pages = 791–3 | date = November 2005 | pmid = 16272104 | doi = 10.1126/science.1114394 | s2cid = 170670241 }}
{{refend}}
{{refend}}
== External links外部链接 ==
== External links ==
{{sisterlinks|d=Q43054|n=no|b=Human_Anatomy/The_Neuron|v=no|voy=no|wikt=neuron|m=no|mw=no|s=no|species=no}}
{{sisterlinks|d=Q43054|n=no|b=Human_Anatomy/The_Neuron|v=no|voy=no|wikt=neuron|m=no|mw=no|s=no|species=no}}
*{{Curlie|Science/Biology/Neurobiology/|Neurobiology}}
*{{Curlie|Science/Biology/Neurobiology/|Neurobiology}}
* [http://www.histology-world.com/photoalbum/thumbnails.php?album=96 Neuron images]
* [http://www.histology-world.com/photoalbum/thumbnails.php?album=96 Neuron images]
* IBRO (国际大脑研究组织)。促进神经科学研究，尤其是在资金不足的国家。
* IBRO (国际大脑研究组织)。促进神经科学研究，尤其是在资金不足的国家。
* NeuronBank 是一个在线神经病学工具，用于编目神经元类型和突触连接。
* NeuronBank 是一个在线神经病学工具，用于编目神经元类型和突触连接。
* NeuroMorpho. Org，一个神经形态学数字重建的在线数据库。
* NeuroMorpho. Org，一个神经形态学数字重建的在线数据库。
* Immunohistochemistry Image Gallery: Neuron
* Immunohistochemistry Image Gallery: Neuron
* Khan Academy: Anatomy of a neuron
* Khan Academy: Anatomy of a neuron
* Neuron images
* Neuron images