New methods for analysing motor function in man and animals

Stein, Richard B.; French, Andrew S.; Mannard, Allan; Yemm, R.

doi:10.1016/0006-8993(72)90126-6

Cited by 130 publications

(65 citation statements)

References 9 publications

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“…Small, low-frequency fluctuations in isometric force output mentioned by Milner-Brown, Stein & Yemm, (1973a) can now be seen as the manifestation of an underlying common drive to all concurrently active motor units. the purpose for this slowly fluctuating synaptic drive is not obvious, although an attractive idea emerges from work on the frequency response ofmotor-unit tension development (Stein, French, Mannard & Yemm, 1972). These investigators showed that as the average firing rates increase in the cat soleus, the responsiveness ofthe muscle to high frequency components ofthe input is reduced, while the response to low frequency components (less than 3 Hz) is enhanced.…”

Section: Correlation Methodsmentioning

confidence: 99%

Control scheme governing concurrently active human motor units during voluntary contractions

Luca

Lefever

McCue

et al. 1982

The Journal of Physiology

444

319

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SUMMARY1. The electrical activity of up to eight concurrently active motor units has been recorded from the human deltoid and first dorsal interosseous muscles. The resulting composite myoelectric signals have been decomposed into their constituent motor-unit action potential trains using a recently developed technique.2. A computer cross-correlation analysis has been performed on motor-unit firing rate and muscle-force output records obtained from both constant-force and triangular force-varying isometric contractions performed by normal subjects, and three groups of highly trained performers (long-distance swimmers, powerlifters and pianists).3. The temporal relationships between firing rate activity and force output have provided evidence that the deltoid of long-distance swimmers has a significantly higher percentage of slowly fatiguing fibres than that of normal subjects. 4. Results showed that both muscles are incapable of producing a purely isotonic contraction under isometric conditions. Small, possibly compensatory force variations at 1-2 Hz result from a common drive to all active motoneurones in a single muscle pool.5. Rapid force reversals during triangular, force-varying isometric contractions appear to be accomplished through a size-related motor-unit control scheme. All firing rates decline prior to the force peak, but small motor units with slow-twitch responses tend to decrease their firing rates before large, fast-twitch motor units. This mechanism is not visually controlled, and does not depend on force rate in non-ballistic contractions.

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Section: Correlation Methodsmentioning

confidence: 99%

Control scheme governing concurrently active human motor units during voluntary contractions

Luca

Lefever

McCue

et al. 1982

The Journal of Physiology

444

319

View full text Add to dashboard Cite

show abstract

“…Surface recordings can also be used jointly with intramuscular recordings to enlarge the number of motor units that are concurrently investigated (Holobar & Zazula 2004). Spike-triggered averaging is also applied to the joint torque for estimating the torque contribution of individual units (Stein et al 1972), although the approach has several limitations (Taylor et al 2002).…”

Section: Spike-triggered Averagingmentioning

confidence: 99%

Analysis of intramuscular electromyogram signals

Merletti

Farina

2008

Phil. Trans. R. Soc. A.

121

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Intramuscular electromyographic (EMG) signals are detected with needles or wires inserted into muscles. With respect to non-invasive techniques, intramuscular electromyography has high selectivity for individual motor unit action potentials and is thus used to measure motor unit activity. Decomposition of intramuscular signals into individual motor unit action potentials consists in detection and classification, usually followed by separation of superimposed action potentials. Although intramuscular EMG signal decomposition is the primary tool for physiological investigations of motor unit properties, it is rarely applied in clinical routine, because of the need for human interaction and the difficulty in interpreting the quantitative data provided by EMG signal decomposition to support clinical decisions. The current clinical use of intramuscular EMG signals relates to the diagnosis of myopathies, of diseases of the α-motor neuron and of the neuromuscular junction through the analysis of the interference signal or of the shape of some motor unit action potentials, usually without a full decomposition of the signal.

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“…The muscle twitch model (Eq. 3) is the impulse response function of a critically damped, second-order visco-elastic system that has been previously tested under isometric conditions (Mannard and Stein 1973;Stein et al 1972). This model provides a good description of the linear behavior of mammalian skeletal muscle in response to a single stimulus in isometric conditions, as in this study.…”

Section: Advantages and Disadvantages Of The Modelsmentioning

confidence: 95%

Method for Counting Motor Units in Mice and Validation Using a Mathematical Model

Major

Hegedus²,

Weber³

et al. 2007

Journal of Neurophysiology

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Major LA, Hegedus J, Weber DJ, Gordon T, Jones KE. Method for counting motor units in mice and validation using a mathematical model. J Neurophysiol 97: 1846 -1856, 2007. First published December 6, 2006; doi:10.1152/jn.00904.2006. Weakness and atrophy are clinical signs that accompany muscle denervation resulting from motor neuron disease, peripheral neuropathies, and injury. Advances in our understanding of the genetics and molecular biology of these disorders have led to the development of therapeutic alternatives designed to slow denervation and promote reinnervation. Preclinical in vitro research gave rise to the need of a method for measuring the effects in animal models. Our goal was to develop an efficient method to determine the number of motor neurons making functional connections to muscle in a transgenic mouse model of amyotrophic lateral sclerosis (ALS). We developed a novel protocol for motor unit number estimation (MUNE) using incremental stimulation. The method involves analysis of twitch waveforms using a new software program, ITS-MUNE, designed for interactive calculation of motor unit number. The method was validated by testing simulated twitch data from a mathematical model of the neuromuscular system. Computer simulations followed the same stimulus-response protocol and produced waveform data that were indistinguishable from experiments. We show that our MUNE protocol is valid, with high precision and small bias across a wide range of motor unit numbers. The method is especially useful for large muscle groups where MUNE could not be done using manual methods. The results are reproducible across naïve and expert analysts, making it suitable for easy implementation. The ITS-MUNE analysis method has the potential to quantitatively measure the progression of motor neuron diseases and therefore the efficacy of treatments designed to alleviate pathologic processes of muscle denervation.

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New methods for analysing motor function in man and animals

Cited by 130 publications

References 9 publications

Control scheme governing concurrently active human motor units during voluntary contractions

Control scheme governing concurrently active human motor units during voluntary contractions

Analysis of intramuscular electromyogram signals

Method for Counting Motor Units in Mice and Validation Using a Mathematical Model

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