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Active propagation of somatic action potentials into neocortical pyramidal cell dendrites
1Max-Planck-Institut für medizinische Forschung, Abteilung Zellphysiologie, Heidelberg, Germany.
Nature
|January 6, 1994
Summary
Action potentials in mammalian neurons initiate in the axon, not dendrites. These signals then actively propagate back into the dendritic tree, challenging previous assumptions about neuronal electrical activity.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
Background:
- Dendrites were traditionally viewed as passive electrical signal integrators.
- Recent evidence suggests dendrites possess active conductances.
- The role of these active dendritic properties in action potential initiation remains unclear.
Purpose of the Study:
- To investigate the role of dendritic active conductances in action potential initiation.
- To determine the precise site of action potential initiation in neocortical pyramidal cells.
Main Methods:
- Patch-clamp recordings from neocortical pyramidal cell dendrites in brain slices.
- Dendritic outside-out patch recordings to identify voltage-activated sodium currents.
- Simultaneous whole-cell recordings from soma and dendrite/axon to pinpoint initiation site.
Main Results:
- Voltage-activated sodium currents were detected in dendritic patches.
- Action potentials were successfully evoked via direct stimulation and synaptic input.
- Action potentials were found to initiate in the axon and propagate retrogradely into the dendrites.
Conclusions:
- Mammalian neuronal action potentials are initiated in the axon.
- Dendrites actively propagate action potentials initiated elsewhere.
- This finding refines our understanding of neuronal signal processing and integration.
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.
01:18Functions of the Nervous System
The nervous system is responsible for coordinating and regulating the body's functions. It functions through three main processes: sensory, integrative, and motor processes. Sensory function involves the detection and transmission of information about internal and external stimuli from sensory receptors to the CNS. The CNS processes this information through an integrative function, where it interprets and makes decisions based on the incoming sensory information. Finally, the motor function...
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...
01:23Propagation 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...