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Regulation of backpropagating action potentials in mitral cell lateral dendrites by A-type potassium currents
1Vollum Institute, Oregon Health and Science University, Portland 97201, USA. christij@ohsu.edu
Journal of Neurophysiology
|May 13, 2003
Summary
Action potentials in olfactory bulb mitral cells are attenuated in lateral dendrites. Blocking A-type potassium channels enhances action potential propagation, suggesting a role in regulating inhibition.
Area of Science:
- Neuroscience
- Olfactory System Physiology
Background:
- Dendrodendritic synapses mediate potent inhibition in the olfactory bulb.
- Effective action potential invasion of dendrites is crucial for inhibitory circuit activation.
- Action potential propagation in mitral cell lateral dendrites remains controversial.
Purpose of the Study:
- To investigate action potential propagation in olfactory bulb mitral cell lateral dendrites.
- To determine the role of A-type potassium channels in regulating action potential amplitude in these dendrites.
Main Methods:
- Paired somatic and dendritic electrophysiological recordings were performed.
- Action potentials were measured in proximal lateral dendrites (0-200 µm from soma).
- Calcium transients evoked by action potentials monitored activity in distal lateral dendrites (200-600 µm from soma).
- The effect of blocking A-type potassium channels with 4-aminopyridine (4-AP) was assessed.
Main Results:
- Somatically elicited action potentials showed attenuation in proximal lateral dendrites.
- Despite attenuation, single action potentials evoked calcium transients throughout the lateral dendrite.
- Blocking A-type potassium channels with 4-AP prevented attenuation and enhanced dendritic calcium transients, especially distally.
Conclusions:
- A-type potassium channels significantly influence action potential amplitude in mitral cell lateral dendrites.
- These channels play a critical role in regulating the extent of action potential propagation into distal dendrites.
- Findings suggest A-type potassium channels are key regulators of olfactory bulb inhibition via mitral cell lateral dendrites.
Related Concept Videos
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...
01:19The 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.
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...
01:28Action 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...
01:23Propagation 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...