Single motor unit firing behavior in the right trapezius muscle during rapid movement of right or left index finger

Søgaard, Karen; Olsen, Henrik Baare; Blangsted, Anne Katrine; Sjøgaard, Gisela

doi:10.3389/fnhum.2014.00881

Cited by 6 publications

(7 citation statements)

References 27 publications

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“…Piotrkiewicz and Kuraszkiewicz ( 2014 ) investigated the relationship between duration of motoneuron AHP and confirmed an earlier observation by Kernell ( 1964 ) that motoneurons with shorter AHPs discharge doublets more easily. Doublets were also mentioned in Søgaard et al ( 2014 ). Triplet discharges have been reported by Piotrkiewicz and Kuraszkiewicz ( 2014 ) and the authors speculate on the possible mechanisms to explain this pattern.…”

mentioning

confidence: 72%

“…Six papers deal with motoneuron discharge related to pathology. Søgaard et al ( 2014 ) recorded electromyographic activity bilaterally from upper trapezius muscles. They observed a tonic low level motor unit activity and suggested that such activity, whether it is built into the motor program to stabilize the limbs or results from stress of paying attention during computer work, may be the underlying cause of myalgia observed in computer workers.…”

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confidence: 99%

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Mechanisms underlying firing in healthy and sick human motoneurons

Piotrkiewicz

Bawa

Schmied

2015

Front. Hum. Neurosci.

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International audienceIn an address to the British Association for the Advancement of Science in Cambridge, Professor Sherrington introduced the terms " motor neurone " and " the final common path, " the latter term implying that all motor commands converge onto the motoneuron which integrates the incoming information and passes the net information to the muscle for contraction (Sherrington, 1904). The relative ease of access of the spinal motoneuron made it feasible to set up techniques for investigating the physiological, biophysical and molecular properties of these neurons. It became the most investigated neuron of the CNS in the twentieth century and the information gained from studies on motoneurons formed the basis for examining the other neurons of the CNS. Since the compound action potential of a muscle unit is strictly related one-to-one to the action potential arriving from the innervating motoneuron, the statistical analysis of muscle unit action potentials provides an investigator with an elegant way to probe the properties of motoneurons in behaving humans. In the following review the terms motoneuron and motor unit might be used interchangeably. Different aspects of human motoneuron investigations in health and disease are presented in 16 articles of this topic which are summarized below. An increase in the net excitatory synaptic input to the motoneuron pool results in an increase in the level of muscle contraction by recruitment of additional motor units (MUs) and an increase in firing rates of the already recruited units (Milner-Brown et al., 1973; Henneman et al., 1974). The principle of orderly recruitment of motoneurons by size was originally proposed by Henneman (1957) but was later questioned by other researchers presenting examples of selective, rather than orderly recruitment (e.g., Smith et al., 1980). These controversies are assessed by Bawa et al. (2014), and the opinion unifying the concept of orderly recruitment is presented. In humans, increases in firing rates of motor units have been shown to follow the " onion skin " pattern at lower levels of contraction, meaning that the lower-threshold motor units discharge with higher rates than higher-threshold ones. However, studies performed on the whole range of muscle forces indicated that for higher force levels the motor unit firing rate follows a " reverse onion skin " pattern. Hu et al. (2014) decided to approach this problem using small surface electrodes and step increases in force instead of the " ramp and hold " protocols used by previous authors. They showed that the " onion skin " pattern was preserved until 15% of maximal voluntary contraction, and from their results predict this pattern to be valid for the whole range of muscle forces, which is not supported by the previous published works. However, the reported rate saturation of the MUs discharging with higher rates implies that at the higher forces the " reverse onion skin " pattern may be expected. In another paper, Duchateau and Baudry (2014) show that during ballistic c...

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confidence: 72%

mentioning

confidence: 99%

Mechanisms underlying firing in healthy and sick human motoneurons

Piotrkiewicz

Bawa

Schmied

2015

Front. Hum. Neurosci.

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“…The latter could be approached with the use of elbow support, which would decrease the need for anticipatory shoulder stabilisation. Maintaining work-related local activity is believed to impair cellular mechanisms, leading to increased input to free nociceptive nerve endings [34]. In conclusion, both headache research and research in physiology and ergonomics support evidence on the involvement and impairment of subparts of the trapezius muscles in continuous daily, and especially workrelated activities, leading to prolonged nociceptive input and hypersensitivity.…”

Section: Lifestyle-related Physical Factors and Resourcesmentioning

confidence: 91%

Children and Adolescents with Primary Tension‐Type Headaches: Research and Practice Perspectives for Non‐ Pharmacological Interdisciplinary Headache Service

Tornøe¹

2017

Current Perspectives on Less-Known Aspects of Headache

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Background: Children and adolescents with frequent and chronic primary headaches are, with a prevalence of 2-23% depending on diagnosis, age, sex and frequency, a global health concern. Research on non-pharmacological treatment outcomes is sparse. Headache service faces a challenge because possible sensitisation of pain pathways can affect outcomes leading to a delay in becoming symptom free or being cured. Method:This chapter provides a narrative review of research containing suggestions for relevant focus areas for professionals who work with children and their parents in the process of self-care. Conclusions:Research supports that increased pericranial tenderness in children with consistent primary tension-type headache is a consequence of activated pain pathways and relevant for clinical assessment. Tension patterns, posture, muscle balance and strength in the neck/shoulder region are areas of importance for minimising the triggering of input to the nociceptive system. Lifestyle factors such as sleep, nutrition, stress and tension regulation, posture and ergonomics, physical activity (PA) and exercise are a key part of non-pharmacological team service. Empowering patient education that provides children and adolescents with the knowledge and drive to persistently pursue healthy lifestyle changes is the basis for potentially successful outcomes in terms of ethical, cultural and educational issues.

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“…Piotrkiewicz and Kuraszkiewicz (2014) investigated the relationship between duration of motoneuron AHP and confirmed an earlier observation by Kernell (1964) that motoneurons with shorter AHPs discharge doublets more easily. Doublets were also mentioned in Søgaard et al (2014). Triplet discharges have been reported by Piotrkiewicz and Kuraszkiewicz (2014) and the authors speculate on the possible mechanisms to explain this pattern.…”

mentioning

confidence: 95%

“…Søgaard et al (2014) recorded electromyographic activity bilaterally from upper trapezius muscles. They observed a tonic low level motor unit activity and suggested that such activity, whether it is built into the motor program to stabilize the limbs or results from stress of paying attention during computer work, may be the underlying cause of myalgia observed in computer workers.…”

mentioning

confidence: 99%

Mechanisms underlying firing in healthy and sick human motoneurons

2015

Frontiers Research Topics

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Keywords: human motoneuron discharge mechanisms, motor unit, afterhyperpolarization and delayed depolarization, double and triple discharges, recruitment and rate coding, axon and peripheral afferents, excitability, motoneuron pathologyIn an address to the British Association for the Advancement of Science in Cambridge, Professor Sherrington introduced the terms "motor neurone" and "the final common path," the latter term implying that all motor commands converge onto the motoneuron which integrates the incoming information and passes the net information to the muscle for contraction (Sherrington, 1904). The relative ease of access of the spinal motoneuron made it feasible to set up techniques for investigating the physiological, biophysical and molecular properties of these neurons. It became the most investigated neuron of the CNS in the twentieth century and the information gained from studies on motoneurons formed the basis for examining the other neurons of the CNS. Since the compound action potential of a muscle unit is strictly related one-to-one to the action potential arriving from the innervating motoneuron, the statistical analysis of muscle unit action potentials provides an investigator with an elegant way to probe the properties of motoneurons in behaving humans. In the following review the terms motoneuron and motor unit might be used interchangeably. Different aspects of human motoneuron investigations in health and disease are presented in 16 articles of this topic which are summarized below.An increase in the net excitatory synaptic input to the motoneuron pool results in an increase in the level of muscle contraction by recruitment of additional motor units (MUs) and an increase in firing rates of the already recruited units (Milner-Brown et al., 1973;Henneman et al., 1974). The principle of orderly recruitment of motoneurons by size was originally proposed by Henneman (1957) but was later questioned by other researchers presenting examples of selective, rather than orderly recruitment (e.g., Smith et al., 1980). These controversies are assessed by Bawa et al. (2014), and the opinion unifying the concept of orderly recruitment is presented. In humans, increases in firing rates of motor units have been shown to follow the "onion skin" pattern at lower levels of contraction, meaning that the lower-threshold motor units discharge with higher rates than higher-threshold ones. However, studies performed on the whole range of muscle forces indicated that for higher force levels the motor unit firing rate follows a "reverse onion skin" pattern. Hu et al. (2014) decided to approach this problem using small surface electrodes and step increases in force instead of the "ramp and hold" protocols used by previous authors. They showed that the "onion skin" pattern was preserved until 15% of maximal voluntary contraction, and from their results predict this pattern to be valid for the whole range of muscle forces, which is not supported by the previous published works. However, the reported rate saturation ...

show abstract

Single motor unit firing behavior in the right trapezius muscle during rapid movement of right or left index finger

Cited by 6 publications

References 27 publications

Mechanisms underlying firing in healthy and sick human motoneurons

Mechanisms underlying firing in healthy and sick human motoneurons

Children and Adolescents with Primary Tension‐Type Headaches: Research and Practice Perspectives for Non‐ Pharmacological Interdisciplinary Headache Service

Mechanisms underlying firing in healthy and sick human motoneurons

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