Related Experiment Video
Updated: Jul 3, 2026
08:08
Real-time Electrophysiology: Using Closed-loop Protocols to Probe Neuronal Dynamics and Beyond
Published on: June 24, 2015
Cortical action potential backpropagation explains spike threshold variability and rapid-onset kinetics.
Yuguo Yu1, Yousheng Shu, David A McCormick
1Department of Neurobiology, Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Summary
Cortical neurons exhibit significant action potential variability due to spike backpropagation. This phenomenon, originating in the axon initial segment, clarifies neuronal processing precision.
Area of Science:
- Neuroscience
- Computational Neuroscience
Background:
- Neocortical action potential responses in vivo display considerable threshold, timing, and rate variability.
- This variability suggests a reliance on cortical ensembles for sensorimotor integration.
- Intracellularly, trial-to-trial variability arises from synaptic activity and its transformation into action potentials.
Purpose of the Study:
- To investigate the sources of action potential variability in cortical neurons.
- To determine the role of spike backpropagation in threshold variability.
- To assess the precision of spike generation in cortical neurons.
Main Methods:
- Simultaneous axonal and somatic recordings in vivo.
- Computational simulations of neuronal activity.
- Analysis of action potential initiation and propagation.
Main Results:
- Spike backpropagation distorts the relationship between synaptic input timing and action potential output.
- Backpropagation causes a high rate of rise in membrane potential at the action potential foot.
- Action potential threshold variability is significantly lower at the axon initial segment compared to the soma.
Conclusions:
- Spike backpropagation creates the appearance of high somatic spike threshold variability.
- Action potential initiation in the axon initial segment is precise and aligns with Hodgkin-Huxley theory.
- Cortical neurons exhibit more precise spike generation than previously assumed.
Related Concept Videos
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
01:28Action Potential: Phases of Stimulation
The action potential is a complex electrical event that occurs in excitable cells, such as neurons and muscle cells. It consists of several distinct phases, each with specific characteristics.
Resting Phase:
In this phase, the cell's membrane is at its resting potential, typically around -70 millivolts (mV) for neurons. Inside the cell, there is a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+). Voltage-gated sodium channels are closed, and...
Resting Phase:
In this phase, the cell's membrane is at its resting potential, typically around -70 millivolts (mV) for neurons. Inside the cell, there is a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+). Voltage-gated sodium channels are closed, and...
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...
01:19The Role of Ion Channels in Neuronal Computation
A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.