Axonal Filtering Allows Reliable Output during Dendritic Plateau-Driven Complex Spiking in CA1 Neurons

Area of Science:

• Neuroscience
• Computational Neuroscience
• Electrophysiology

Background:

• Correlated inputs in CA1 pyramidal neurons generate dendritic plateau potentials.
• These potentials modulate neuronal plasticity and firing rates.
• Axon-soma electrotonic coupling raises questions about plateau influence on action potential initiation.

Purpose of the Study:

• To investigate how dendritic plateau potentials affect action potential initiation, propagation, and neurotransmitter release.
• To determine the role of axonal properties in shaping the impact of plateau potentials.

Main Methods:

• Experiments in brain slices and awake mice.
• Development and use of a computational model.
• Electrophysiological recordings and analysis of action potential properties.

Main Results:

• Plateau potentials caused significant somatic and proximal axon Na(+) channel inactivation.
• Action potentials initiated by plateaus recovered to full amplitude in the distal axon (>150 μm).
• Neurotransmitter release triggered by plateau-evoked action potentials was similar to regular spiking.

Conclusions:

• Axonal K(+) channels strongly attenuate plateau depolarizations, enabling full axon repolarization and Na(+) channel deinactivation.
• This mechanism allows for accurate transmission of gain-modulated firing rates.
• Axonal filtering of dendritic plateaus supports neuronal firing rate coding for downstream regions.