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Action potential initiation and propagation in rat neocortical pyramidal neurons
G Stuart1, J Schiller, B Sakmann
1Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany. Greg.Stuart@anu.edu.au
The Journal of Physiology
|February 11, 1998
Summary
Neocortical layer 5 pyramidal neurons initiate action potentials in the axon, not the soma. Dendritic regenerative potentials occur but are attenuated, ensuring axonal action potential initiation precedes somatic firing.
Area of Science:
- Neuroscience
- Electrophysiology
- Computational Neuroscience
Background:
- Layer 5 pyramidal neurons are critical for cortical output.
- Understanding action potential initiation is key to neuronal function.
Purpose of the Study:
- Investigate action potential initiation and propagation in neocortical layer 5 pyramidal neurons.
- Determine the role of dendritic regenerative potentials in action potential initiation.
Main Methods:
- Simultaneous dual and triple patch pipette recordings from neocortical layer 5 pyramidal neurons.
- Extracellular synaptic stimulation and current injections.
- Voltage recordings from soma, dendrites, and axon initial segment.
Main Results:
- Distal synaptic stimulation can evoke dendritic regenerative potentials prior to somatic action potentials.
- Back-propagating action potentials in dendrites are frequency-dependent and associated with calcium electrogenesis.
- Action potentials are consistently initiated in the axon initial segment before the soma.
- Dendritic regenerative potentials are attenuated upon reaching the soma and axon.
Conclusions:
- Both dendrites and the axon can initiate regenerative potentials in layer 5 pyramidal neurons.
- Axonal initiation of action potentials precedes somatic initiation, regardless of dendritic activity.
- Dendritic potentials are significantly attenuated, leading to reliable axonal action potential generation.