Related Experiment Video
Updated: Apr 6, 2026
13:07
Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo
Published on: December 5, 2012
15.3K
Motor unit firing pattern: evidence for motoneuronal or axonal discharge origin?
Lydia P Kudina1, Regina E Andreeva2
1Institute for Information Transmission Problems (Kharkevich Institute), Russian Academy of Sciences, 19, Bol'shoi Karetnyi pereulok, GSP-4, 127994, Moscow, Russia. kudina@iitp.ru.
Summary
Doublet intervals alone do not reliably indicate axonal firing in neuromuscular diseases. Further evidence, like the F-wave, is needed to distinguish motoneuronal from axonal fasciculations.
Area of Science:
- Neurology
- Neurophysiology
- Motor Control
Background:
- The origin of fasciculations in neuromuscular diseases remains debated.
- Previous research suggested motor unit firing patterns, specifically doublet intervals, could differentiate motoneuronal from axonal origins.
Purpose of the Study:
- To investigate the reliability of doublet intervals as a sole indicator of axonal firing.
- To compare doublet intervals originating from motoneurons versus axons in healthy individuals.
Main Methods:
- Elicited H-reflex and M-response of single motor units during voluntary contractions in healthy subjects.
- Utilized peri-stimulus time histograms to determine doublet origin based on latency (motoneuronal vs. axonal).
Main Results:
- No significant difference was found between motoneuronal and axonal doublet intervals.
- The latency difference in peri-stimulus time histograms reliably distinguished doublet origins.
Conclusions:
- Doublet interval alone is not a sufficient criterion for identifying axonal firing.
- Additional evidence, such as the F-wave, is necessary for accurate diagnosis.
- This methodology can aid in understanding motor unit disease mechanisms.
Keywords:
Axonal and motoneuronal double dischargesFasciculation potentialsHuman firing motor unitsInterspike interval analysisMore Related Videos
Related Concept Videos
01:20Motor Unit Stimulation
4.9K
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
4.9K
00:46Motor Units
63.2K
A motor unit consists of two main components: a single efferent motor neuron (i.e., a neuron that carries impulses away from the central nervous system) and all of the muscle fibers it innervates. The motor neuron may innervate multiple muscle fibers, which are single cells, but only one motor neuron innervates a single muscle fiber.
63.2K
01:13Motor Units
10.1K
The motor unit is a fundamental component of the neuromuscular system and plays a crucial role in coordinating muscle contractions. It consists of a somatic motor neuron, which connects and controls multiple skeletal muscle fibers, forming a single functional segment. The axon of the motor neuron branches out and establishes synaptic connections known as neuromuscular junctions with individual muscle fibers within the motor unit.
Motor units come in different sizes, with smaller units...
Motor units come in different sizes, with smaller units...
10.1K
01:14Action Potential
12.4K
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...
12.4K
01:14Action Potential
8.7K
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...
8.7K
01:18Functions of the Nervous System
9.5K
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...
9.5K