Active propagation of somatic action potentials into neocortical pyramidal cell dendrites

• Published in: Nature (London) Vol. 367; no. 6458; pp. 69 - 72
• Main Authors: Stuart, Greg J, Sakmann, Bert
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 06.01.1994; Nature Publishing Group
• Subjects: Action Potentials; Animals; Axons - physiology; Biological and medical sciences; Central nervous system; Dendrites; Dendrites - physiology; Electrophysiology; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; Lidocaine - analogs & derivatives; Lidocaine - pharmacology; Medical research; Nervous system; Neurology; Pyramidal Cells - physiology; Rats; Rats, Wistar; Sodium Channel Blockers; Sodium Channels - metabolism; Vertebrates: nervous system and sense organs; Propagation; Rat; Rodentia; Central nervous system; Electrophysiology; Action potential; Ionic current; Dendrite; Vertebrata; Mammalia; Pericaryon; Sodium; Ionic conductance; Pyramidal neuron; Hippocampus; Brain (vertebrata)
• ISSN: 0028-0836; 1476-4687
• 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.