Stuart G J, Sakmann B
Max-Planck-Institut für medizinische Forschung, Abteilung Zellphysiologie, Heidelberg, Germany.
Nature. 1994 Jan 6;367(6458):69-72. doi: 10.1038/367069a0.
The dendrites of neurons in the mammalian central nervous system have been considered as electrically passive structures which funnel synaptic potentials to the soma and axon initial segment, the site of action potential initiation. More recent studies, however, have shown that the dendrites of many neurons are not passive, but contain active conductances. The role of these dendritic voltage-activated channels in the initiation of action potentials in neurons is largely unknown. To assess this directly, patch-clamp recordings were made from the dendrites of neocortical pyramidal cells in brain slices. Voltage-activated sodium currents were observed in dendritic outside-out patches, while action potentials could be evoked by depolarizing current pulses or by synaptic stimulation during dendritic whole-cell recordings. To determine the site of initiation of these action potentials, simultaneous whole-cell recordings were made from the soma and the apical dendrite or axon of the same cell. These experiments showed that action potentials are initiated first in the axon and then actively propagate back into the dendritic tree.
哺乳动物中枢神经系统中神经元的树突一直被认为是电被动结构，它将突触电位汇集到胞体和轴突起始段，即动作电位起始的部位。然而，最近的研究表明，许多神经元的树突并非被动的，而是含有主动电导。这些树突电压激活通道在神经元动作电位起始中的作用在很大程度上尚不清楚。为了直接评估这一点，对脑片上新皮质锥体细胞的树突进行了膜片钳记录。在树突外向型膜片中观察到电压激活的钠电流，而在树突全细胞记录期间，去极化电流脉冲或突触刺激可诱发动作电位。为了确定这些动作电位的起始部位，对同一细胞的胞体和顶端树突或轴突进行了同步全细胞记录。这些实验表明，动作电位首先在轴突中起始，然后主动传播回树突树。
