Related Experiment Video
Updated: Feb 22, 2026
ALS - Motor Neuron Disease: Mechanism and Development of New Therapies
Published on: July 29, 2007
Interplay of upper and lower motor neuron degeneration in amyotrophic lateral sclerosis
Mamede de Carvalho1, Artiom Poliakov1, Cristiano Tavares1
1Instituto de Medicina Molecular and Institute of Physiology, Faculty of Medicine, University of Lisbon, Portugal.
Objective:
We studied motor unit recruitment to test a new method to identify motor unit firing rate (FR) variability.
Methods:
We studied 68 ALS patients, with and without upper neuron signs (UMN) in lower limbs, 24 patients with primary lateral sclerosis (PLS), 13 patients with spinal cord lesion and 39 normal subjects. All recordings were made from tibialis anterior muscles of normal strength. Subjects performed a very slight contraction in order to activate 2 motor units in each recording. 5-7 motor unit pairs were recorded in each subject. Mean consecutive differences (MCD) were calculated for each pair of potentials. The mean MCD for each muscle was estimated as the mean from the total number of pairs recorded. Ap value<0.01 was accepted as significant.
Results:
MCD of FR frequency was less in the subjects with spinal cord lesion and PLS. In addition, the FR frequency of the 1st motor unit in a pair of units was markedly reduced in PLS, and in subjects with spinal cord lesions.
Conclusion:
These results support a lower threshold and reduced FR fluctuation in spinal motor neurons of spastic patients.
Significance:
This method can be developed for detection of UMN lesions.
More Related Videos
08:16Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
Published on: March 4, 2014
06:35In Vivo Electrophysiological Measurement of Compound Muscle Action Potential from the Forelimbs in Mouse Models of Motor Neuron Degeneration
Published on: June 15, 2018
Related Concept Videos
01:26Cross-bridge Cycle
01:26Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:26Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:11Direct Motor Pathways
The corticospinal tract is responsible for the voluntary movement of the limbs and trunk. It originates in the cerebral cortex of the brain and descends through the cerebrum's internal capsule and...
01:15Parkinson's Disease: Overview
01:37Neural Regulation