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In Situ Visualization of Axon Growth and Growth Cone Dynamics in Acute Ex Vivo Embryonic Brain Slice Cultures
Published on: October 14, 2021
The axon as a unique computational unit in neurons.
1Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan. t.sasaki.0224@gmail.com
Neuroscience Research
|January 10, 2013
Summary
Mammalian cortical axons, traditionally viewed as passive signal transmitters, can actively modulate action potentials (APs). This dynamic AP waveform regulation influences neurotransmission and network activity, challenging the all-or-none propagation model.
Area of Science:
- Neuroscience
- Cellular Biology
- Computational Neuroscience
Background:
- Mammalian cortical axons are extensively branched, connecting numerous neurons over significant distances.
- The conventional model posits all-or-none action potential (AP) initiation at the axon initial segment and distortion-free propagation.
- Recent findings challenge this by revealing AP waveform modulation in axons.
Purpose of the Study:
- To explore the functional implications of dynamic axonal action potential modulation.
- To investigate the role of ion channel and receptor states in altering axonal AP waveforms.
- To examine the contribution of axonal activity to network oscillations and information processing.
Main Methods:
- Electrophysiological recordings in mammalian cortical neurons.
- Pharmacological manipulation of axonal ion channels and receptors.
- Computational modeling of axonal signal propagation and integration.
Main Results:
- Axonal AP waveforms are modifiable by the state of axonal ion channels and receptors.
- AP modulation influences neurotransmission efficacy to postsynaptic targets.
- Cortical axons integrate somatic burst firing and generate activity-dependent ectopic APs.
- These axonal mechanisms contribute to fast rhythmic network activity (oscillogenesis).
Conclusions:
- Mammalian cortical axons possess sophisticated functional capabilities beyond simple signal conduction.
- Axonal AP modulation represents a key mechanism for regulating neuronal communication and network dynamics.
- The prevailing model of axon physiology needs revision to incorporate these dynamic axonal functions.
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The axon attaches to the cell body at a cone-shaped elevation called the axon hillock. The initial part of the axon, closest to the hillock, is known as the initial segment.
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