A dominant role for mechanical resonance in physiological finger tremor revealed by selective minimization of voluntary drive and movement

Vernooij, Carlijn A.; Reynolds, Raymond F.; Lakie, Martin

doi:10.1152/jn.00926.2012

Cited by 23 publications

(32 citation statements)

References 42 publications

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“…This kinetic tremor was attributed by Vallbo and Wessberg (1993) to a shift to an intermittent or discrete form of neural control during movement and has formed the basis for a hypothetical model of intermittent control (Bye and Neilson 2010). However, we have recently suggested an alternative explanation (Vernooij et al 2013) that is in line with the current results. We believe that the low-frequency peak is produced by a thixotropic reduction in muscle stiffness and damping, excited by broadband noise from the active muscles.…”

Section: Discussionsupporting

confidence: 85%

“…Consequently, it is thought that a different explanation has to be invoked for the lower frequency peak (typically 8 -12 Hz, or simply "10-Hz tremor"). Finger tremor at this frequency is particularly prominent during movement (Vallbo and Wessberg 1993) and is usually explained in terms of increased synchronized modulation of contributing motor units produced by reflex or central mechanisms (reviewed by McAuley and Marsden 2000).Alternatively, our recent results suggest that both characteristic frequencies (including the 10-Hz component) of physiological finger tremor might be produced by a resonant mechanism (Vernooij et al 2013). In this study, we compared isotonic finger tremor with its isometric counterpart, where movement, and thus resonance, was prevented.…”

mentioning

confidence: 76%

“…If the stretch reflex does contribute to physiological tremor, it would be expected to generate a finger tremor frequency of ϳ10 Hz (Durbaba et al 2005;Lippold 1970). In nonimpaired persons, this tremor frequency becomes dominant at higher intensities of electrical stimulation (Vernooij et al 2013). Therefore, to determine the effect of an absent stretch reflex on this particular frequency, we electrically stimulated the muscle of both impaired subjects at a level comparable to highest intensity applied to the nonimpaired ("control") volunteers.…”

Section: Voluntary Physiological Finger Tremor (Voluntary Condition)mentioning

confidence: 99%

“…We used a low-pass filter (Bawa and Stein 1976) with a time constant of 34 ms to filter the artificial input signal for the electrical condition only. This time constant turned out to best represent the muscular force twitch constant produced by a single stimulus and by a train of electrical stimuli that we measured in our previous study (Vernooij et al 2013). The spectra were converted to torque spectra by multiplying the force by a finger moment arm (estimated at 10 cm).…”

Section: Voluntary Physiological Finger Tremor (Voluntary Condition)mentioning

confidence: 99%

“…Alternatively, our recent results suggest that both characteristic frequencies (including the 10-Hz component) of physiological finger tremor might be produced by a resonant mechanism (Vernooij et al 2013). In this study, we compared isotonic finger tremor with its isometric counterpart, where movement, and thus resonance, was prevented.…”

mentioning

confidence: 95%

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The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

Vernooij

Lakie

Reynolds

2015

Journal of Neurophysiology

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Two frequency peaks of variable preponderance have been reported for human physiological finger tremor. The high-frequency peak (20-25 Hz, seen only in postural tremor) is generally attributed to mechanical resonance, whereas the lower frequency peak (8-12 Hz, seen in both postural and kinetic tremor) is usually attributed to synchronous central or reflexive neural drive. In this study, we determine whether mechanical resonance could generate both peaks. In relaxed subjects, an artificial finger tremor was evoked by random mechanical perturbations of the middle finger or random electrical muscular stimulation of the finger extensor muscle. The high and the low frequencies observed in physiological tremor could both be created by either type of artificial input at appropriate input intensity. Resonance, inferred from cross-spectral gain and phase, occurred at both frequencies. To determine any neural contribution, we compared truly passive subjects with those who exhibited some electromyographic (EMG) activity in the finger extensor; artificially created tremor spectra were almost identical between groups. We also applied electrical stimuli to two clinically deafferented subjects lacking stretch reflexes. They exhibited the same artificial tremor spectrum as control subjects. These results suggest that both typical physiological finger tremor frequencies can be reproduced by random artificial input; neither requires synchronized neural input. We therefore suggest that mechanical resonance could generate both dominant frequency peaks characteristic of physiological finger tremor. The inverse relationship between the input intensity and the resulting tremor frequency can be explained by a movement-dependent reduction in muscle stiffness, a conjecture we support using a simple computational model.

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Section: Discussionsupporting

confidence: 85%

mentioning

confidence: 76%

Section: Voluntary Physiological Finger Tremor (Voluntary Condition)mentioning

confidence: 99%

Section: Voluntary Physiological Finger Tremor (Voluntary Condition)mentioning

confidence: 99%

mentioning

confidence: 95%

See 3 more Smart Citations

The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

Vernooij

Lakie

Reynolds

2015

Journal of Neurophysiology

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Postural Tremors

Daneault,

Duval

2023

Contemporary Clinical Neuroscience

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Voluntary reduction of force variability via modulation of low-frequency oscillations

et al. 2017

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Visual feedback can influence the force output by changing the power in frequencies below 1 Hz. However, it remains unknown whether visual guidance can help an individual reduce force variability voluntarily. The purpose of this study, therefore, was to determine whether an individual can voluntarily reduce force variability during constant contractions with visual guidance, and whether this reduction is associated with a decrease in the power of low-frequency oscillations (0-1 Hz) in force and muscle activity. Twenty young adults (27.6 ± 3.4 years) matched a force target of 15% MVC (maximal voluntary contraction) with ankle dorsiflexion. Participants performed six visually unrestricted contractions, from which we selected the trial with the least variability. Following, participants performed six visually guided contractions and were encouraged to reduce their force variability within two guidelines (±1 SD of the least variable unrestricted trial). Participants decreased the SD of force by 45% (P < 0.001) during the guided condition, without changing mean force (P > 0.2). The decrease in force variability was associated with decreased low-frequency oscillations (0-1 Hz) in force (R = 0.59), which was associated with decreased low-frequency oscillations in EMG bursts (R = 0.35). The reduction in low-frequency oscillations in EMG burst was positively associated with power in the interference EMG from 35 to 60 Hz (R = 0.47). In conclusion, voluntary reduction of force variability is associated with decreased low-frequency oscillations in EMG bursts and consequently force output. We provide novel evidence that visual guidance allows healthy young adults to reduce force variability voluntarily likely by adjusting the low-frequency oscillations in the neural drive.

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A dominant role for mechanical resonance in physiological finger tremor revealed by selective minimization of voluntary drive and movement

Abstract: Vernooij CA, Reynolds RF, Lakie M. A dominant role for mechanical resonance in physiological finger tremor revealed by selective minimization of voluntary drive and movement.

Cited by 23 publications

References 42 publications

The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive

Postural Tremors

Voluntary reduction of force variability via modulation of low-frequency oscillations

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