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Updated: May 23, 2026
07:40
Measuring Properties of the Membrane Periodic Skeleton of the Axon Initial Segment using 3D-Structured Illumination Microscopy (3D-SIM)
Published on: February 11, 2022
The physiology of the axon initial segment.
Kevin J Bender1, Laurence O Trussell
1Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, USA. kbender@gallo.ucsf.edu
Annual Review of Neuroscience
|March 27, 2012
Summary
The axon initial segment (AIS) initiates action potentials and possesses complex molecular machinery. Recent research reveals the AIS is a critical control site for neuronal excitability, not just the axon
Area of Science:
- Neuroscience
- Cell Biology
Background:
- The axon initial segment (AIS) is traditionally recognized as the primary site for action potential initiation.
- Decades of research have confirmed this fundamental role in neuronal function.
Purpose of the Study:
- To explore the complex molecular biology and functional significance of the AIS.
- To highlight the AIS's role beyond simple action potential initiation.
Main Methods:
- Review of existing research on AIS molecular composition and function.
- Analysis of mechanisms regulating ion channel localization and membrane domain specialization within the AIS.
Main Results:
- The AIS exhibits a complex molecular composition with diverse ion channels.
- Specialized membrane domains within the AIS contribute to distinct roles in neuronal excitation.
- AIS function is dynamically regulated by neurotransmitters and activity-dependent processes.
Conclusions:
- The AIS is a highly specialized and dynamic region crucial for controlling neuronal excitability.
- The AIS is more than just the start of the axon; it is a key regulatory hub.
Related Concept Videos
01:21Neurons: The Axon
Axons are long, cytoplasmic processes of nerve cells capable of propagating electrical impulses known as action potentials. The cytoplasm or axoplasm of an axon contains neurofibrils, neurotubules, small vesicles, lysosomes, mitochondria, and various enzymes, all encased within the axolemma, the plasma membrane of the axon.
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.
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.
01:23Propagation of Action Potentials
The propagation of an action potential refers to the process by which a nerve impulse, or "action potential," travels along a neuron.
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
01:41Action Potentials
Overview
01:14Action Potential
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
01:14Action Potential
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
01:25Nervous Tissue: Myelin
The myelin sheath is a multilayered lipid and protein covering that insulates the axon of a neuron, enhancing the speed of nerve impulse conduction. Axons without this sheath are referred to as unmyelinated. Two types of neuroglia, Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS) are responsible for producing myelin sheaths.
Schwann cells begin to form myelin sheaths around axons during fetal development. They wrap around a small...
Schwann cells begin to form myelin sheaths around axons during fetal development. They wrap around a small...