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Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury
Published on: November 19, 2012
Distance-dependent modifiable threshold for action potential back-propagation in hippocampal dendrites.
1Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA. cbernard@inmed.univ-mrs.fr
Journal of Neurophysiology
|September 11, 2003
Summary
The study identifies a threshold potential that dictates whether back-propagating action potentials (b-APs) in hippocampal neurons are weak or strong. This threshold, influenced by ion channels, determines how far b-APs propagate into dendrites, impacting neuronal function.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Cellular Electrophysiology
Background:
- Action potentials in hippocampal CA1 pyramidal neurons back-propagate into the dendritic tree.
- The amplitude of these back-propagating action potentials (b-APs) influences synaptic integration and plasticity.
- Membrane potential (Vm) is a key factor controlling b-AP amplitude during propagation.
Purpose of the Study:
- To investigate the relationship between dendritic location, membrane potential, and the amplitude of back-propagating action potentials.
- To identify the threshold potential governing the transition between weak (passive) and strong (active) b-AP propagation.
- To determine how ion channel states affect this transition threshold.
Main Methods:
- Computational modeling of hippocampal CA1 pyramidal neurons.
- Simulations of back-propagating action potentials at various dendritic locations.
- Analysis of the effects of altered Na+ and K+ channel function on b-AP propagation.
Main Results:
- A dendritic location-dependent threshold potential (x) was identified, controlling b-AP amplitude.
- When Vm exceeds x, b-APs are strong (active); when Vm is below x, b-APs are weak (passive).
- The threshold potential (x) varies linearly with distance from the soma and is modulated by Na+ and K+ channel states.
Conclusions:
- The threshold potential (x) parameterizes the transition from weak to strong b-AP propagation in dendrites.
- Modifications to x, via ion channel modulation, can alter the extent of strong b-AP propagation.
- Changes in b-AP propagation range may have significant implications for dendritic function in health and disease.
Related Concept Videos
Action Potentials
Overview
Long-term Potentiation
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre- and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
Action 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...
Long-term Potentiation
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
Hebbian LTP
LTP can occur when presynaptic neurons...
Hebbian LTP
LTP can occur when presynaptic neurons...
Action 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...
Propagation 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...

