From the Department of Neurology, Mayo Clinic, Rochester, MN.
Neurology. 2014 Mar 18;82(11):989-99. doi: 10.1212/WNL.0000000000000228. Epub 2014 Feb 14.
Neurons contain different functional somatodendritic and axonal domains, each with a characteristic distribution of voltage-gated ion channels, synaptic inputs, and function. The dendritic tree of a cortical pyramidal neuron has 2 distinct domains, the basal and the apical dendrites, both containing dendritic spines; the different domains of the axon are the axonal initial segment (AIS), axon proper (which in myelinated axons includes the node of Ranvier, paranodes, juxtaparanodes, and internodes), and the axon terminals. In the cerebral cortex, the dendritic spines of the pyramidal neurons receive most of the excitatory synapses; distinct populations of γ-aminobutyric acid (GABA)ergic interneurons target specific cellular domains and thus exert different influences on pyramidal neurons. The multiple synaptic inputs reaching the somatodendritic region and generating excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) sum and elicit changes in membrane potential at the AIS, the site of initiation of the action potential.
神经元包含不同功能的树突和轴突域，每个域都具有特征性的电压门控离子通道、突触输入和功能分布。皮质锥体神经元的树突树有 2 个不同的域，即基底树突和顶树突，两者都包含树突棘；轴突的不同域是轴突起始段（AIS）、轴突主干（在有髓鞘的轴突中包括郎飞结、旁突、节间段和轴突节段）和轴突末端。在大脑皮层中，锥体神经元的树突棘接收大部分兴奋性突触；不同群体的γ-氨基丁酸（GABA）能中间神经元针对特定的细胞域，因此对锥体神经元施加不同的影响。到达树突和轴突区域并产生兴奋性突触后电位（EPSP）和抑制性突触后电位（IPSP）的多个突触输入在动作电位起始部位的 AIS 处进行总和，并引发膜电位的变化。
