Physiological tremor of the upper limb segments

Takanokura, Masato; Sakamoto, Kazuyoshi

doi:10.1007/s004210100476

Cited by 31 publications

(33 citation statements)

References 26 publications

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“…When the LVDT was not attached, power in the 4−8 Hz band for displacement increased with the load supported by the finger. The shapes and locations of the peaks in the spectra for displacement and acceleration when the LVDT was not attached were similar to those reported previously for the index finger (Duval and Jones, 2005;Randall and Stiles, 1964;Stiles and Hahs, 1991;Takanokura and Sakamoto, 2001). The reduction in the frequency for the peak with an increase in load suggests that the fluctuations were most likely influenced by the oscillations at resonant frequencies of the system that depend on mechanical factors, such as its mass and stiffness of the entire finger including the muscle (Stiles and Randall, 1967).…”

Section: Frequency Content and Correlation Between Measures Of Fluctusupporting

confidence: 84%

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Shinohara

Keenan

Enoka

2008

Journal of Neuroscience Methods

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Fluctuations in motor output are typically quantified by the standard deviation (SD) of displacement or acceleration. The aim of the study was to determine the influence of a linear variable-displacement transducer (LVDT) on the SDs and spectral content of displacement and acceleration during steady isometric and anisometric contractions performed with the first dorsal interosseus muscle. Thirteen young adults supported six loads when performing position-holding and position-tracking tasks when the LVDT either was or was not attached to the index finger. The LVDT reduced the magnitude of the SDs in displacement and acceleration and disrupted the load-dependent modulation of the spectral properties of these signals. When the LVDT was not connected to the finger, the displacement SD was greatest during concentric contractions, the acceleration SD was greatest during eccentric contractions, and there were load-dependent changes in the power density spectra. Although the LVDT may be used for assessing relative changes in displacement, its ability to provide absolute measures of fluctuations in motor output is limited. The results provide baseline measures of the fluctuations in motor output during steady contractions with a hand muscle and how the method used to detect displacement alters these measures.

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Section: Frequency Content and Correlation Between Measures Of Fluctusupporting

confidence: 84%

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Shinohara

Keenan

Enoka

2008

Journal of Neuroscience Methods

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“…Tremor is defined as an involuntary and continuous oscillation in every limb segment of a healthy human. It has been shown that tremor in any limb segment is composed of two frequency components (Takanokura and Sakamoto 2001). It has been hypothesized that the two frequency components of tremor are generated from components of the nervous system.…”

Section: Introductionmentioning

confidence: 99%

The origins of physiological tremor as deduced from immersions of the finger in various liquids

Takanokura

Kokuzawa

Sakamoto

2002

European Journal of Applied Physiology

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To investigate the influence of gravity on physiological tremor during a holding stretch of the finger, tremor during immersion of the finger in liquids was measured. Liquids with various densities and various coefficients of viscosity were used. Tremor was detected using an acceleration sensor, and power spectrum analysis was performed on the acceleration signal of the tremor. The total power of the tremor spectrum decreased with an increase of the density and an increase of the coefficient of viscosity, the high frequency domain of the tremor spectrum showing a larger decrease than the low frequency domain. Linear regression analysis showed that the viscosity of the liquid had a larger effect on tremor than the buoyancy due to the liquid. A model was proposed for tremor during immersion of the finger in liquid. The effect of the buoyancy and the viscosity on tremor was examined using the proposed model. The origin of two frequency bands in the tremor spectrum was verified by both the immersion experiment and the proposed model. The stretch-reflex system via the spinal cord produced a high frequency band around 25 Hz, while the supraspinal system caused a low frequency band around 10 Hz. The neuromuscular function of the human body was evaluated using the amplitude and the frequency of tremor.

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“…Although tremor in the frequency range of physiological tremor 24 was evident in two of the primates, it was only noticeable when the myo-chem index was at its highest level, corresponding to the greatest cumulative dose of DFP. At lower doses, the myo-chem index was more sensitive than the tremor index.…”

Section: Discussionmentioning

confidence: 92%

The electromyographic signal as a presymptomatic indicator of organophosphates in the body

et al. 2005

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Organophosphate (OP) compounds are present in household and agricultural pesticides as well as in nerve agents. The toxic effects of these chemicals result from their anticholinesterase activity, which disrupts nerve junctions and parasympathetic effector sites, leading to a variety of symptoms and possible death. When the anticholinesterase agents in OP compounds reach the neuromuscular junction, they cause a disruption in the firing of muscle fiber action potentials. This effect has the potential of altering the time course of the electromyographic (EMG) signal detected by surface electrodes. We investigated the association between OP compound dose, surface EMG changes, and overt signs of OP toxicity. Daily doses of 10-15 microg/kg of diisopropylfluorophosphate (DFP) were injected into the calf muscle of four rhesus monkeys while surface EMG signals were recorded from two thigh muscles bilaterally. With increasing number of doses, the EMG signal presented an increasing number of time gaps. The presence of the gaps was evident prior to any overt symptoms of cholinesterase toxicity. These findings can lead to the development of noninvasive technology for indicating the presence of OP compounds in muscle tissue prior to clinical abnormalities.

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Physiological tremor of the upper limb segments

Cited by 31 publications

References 26 publications

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

Fluctuations in motor output of a hand muscle can be altered by the mechanical properties of the position sensor

The origins of physiological tremor as deduced from immersions of the finger in various liquids

The electromyographic signal as a presymptomatic indicator of organophosphates in the body

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