The Axon Initial Segment is the Dominant Contributor to the Neuron's Extracellular Electrical Potential Landscape
The Axon Initial Segment is the Dominant Contributor to the Neuron's Extracellular Electrical Potential Landscape
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DOI：
10.1002/adbi.201800308
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发表时间：
2019-02-01
影响因子：
4.1
通讯作者：
Hierlemann, Andreas
中科院分区：
文献类型：
--
作者：
Bakkum, Douglas J.;Obien, Marie Engelene J.;Hierlemann, Andreas
由神经元动作电位产生的细胞外电压场为研究神经元和神经元网络功能提供了广泛使用的手段。神经元的胞体和树突被认为是细胞外动作电位(EAP)的驱动因素，而轴突的作用通常被认为不那么重要。然而，通过数百个密集填充的电极记录分离的大鼠皮质培养中的单个神经元和急性小脑切片中的浦肯野细胞的电压，发现轴突起始段主导着所测量的EAP景观，令人惊讶的是，胞体只起到很小的作用。正如预期的那样，记录的主导信号具有负极性(进入电池的电荷)，并在远端启动。有趣的是，具有正极性的信号(离开细胞的电荷)出现在一些但不是所有树突分支附近，并在延迟后出现。对于解释来自所有电读数方案的结果，这些关于哪些神经元隔间对细胞外电压格局有贡献的基本知识是重要的。最后，证实了轴突起始段(AIS)远端的电活动开始，随后通过AIS近端向胞体向后扩散到轴突。可以跟踪不同神经元隔间对应的细胞外波形。
Extracellular voltage fields, produced by a neuron's action potentials, provide a widely used means for studying neuronal and neuronal-network function. The neuron's soma and dendrites are thought to drive the extracellular action potential (EAP) landscape, while the axon's contribution is usually considered less important. However, by recording voltages of single neurons in dissociated rat cortical cultures and Purkinje cells in acute mouse cerebellar slices through hundreds of densely packed electrodes, it is found, instead, that the axon initial segment dominates the measured EAP landscape, and, surprisingly, the soma only contributes to a minor extent. As expected, the recorded dominant signal has negative polarity (charge entering the cell) and initiates at the distal end. Interestingly, signals with positive polarity (charge exiting the cell) occur near some but not all dendritic branches and occur after a delay. Such basic knowledge about which neuronal compartments contribute to the extracellular voltage landscape is important for interpreting results from all electrical readout schemes. Finally, initiation of the electrical activity at the distal end of the axon initial segment (AIS) and subsequent spreading into the axon proper and backward through the proximal AIS toward the soma are confirmed. The corresponding extracellular waveforms across different neuronal compartments could be tracked.