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

Park, Seoung Hoon; Casamento‐Moran, Agostina; Yacoubi, Basma El; Christou, Evangelos A.

doi:10.1007/s00221-017-5005-5

Cited by 19 publications

(10 citation statements)

References 61 publications

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“…Even though the task was not cognitively challenging, it did require a certain level of attention. Therefore, age-associated decreases in the high-frequency components of the neural drive to muscle may have reflected an impairment in the cortical control that contributed to the augmented fluctuations of common input at lower frequencies (Kwon et al 2012;Lodha and Christou 2017;Park et al 2017). Because of the weak association between gamma coherence and age and the relatively small sample size in our study, however, this interpretation should be further tested in future studies.…”

Section: Discussionmentioning

confidence: 77%

“…Therefore, assuming an approximately linear transmission of common input by the pool of motor neurons (Negro and Farina 2011), the neural drive to muscle produces a force that reflects the low-frequency components of the common synaptic input (Farina et al 2014(Farina et al , 2016. Accordingly, previous studies have suggested that lowfrequency oscillations in force (Ͻ0.5 Hz) during voluntary contractions can be modulated by increasing the frequency of oscillation with visual feedback and motor training (Fox et al 2013;Lodha and Christou 2017;Moon et al 2014;Park et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Castronovo

Mrachacz-Kersting

Stevenson

et al. 2018

Journal of Neurophysiology

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Declines in motor function with advancing age have been attributed to changes occurring at all levels of the neuromuscular system. However, the impact of aging on the control of muscle force by spinal motor neurons is not yet understood. In this study on 20 individuals aged between 24 and 75 yr (13 men, 7 women), we investigated the common synaptic input to motor neurons of the tibialis anterior muscle and its impact on force control. Motor unit discharge times were identified from high-density surface EMG recordings during isometric contractions at forces of 20% of maximal voluntary effort. Coherence analysis between motor unit spike trains was used to characterize the input to motor neurons. The decrease in force steadiness with age ( R = 0.6, P < 0.01) was associated with an increase in the amplitude of low-frequency oscillations of functional common synaptic input to motor neurons ( R = 0.59; P < 0.01). The relative proportion of common input to independent noise at low frequencies increased with variability (power) in common synaptic input. Moreover, variability in interspike interval did not change and strength of the common input in the gamma band decreased with age ( R = 0.22; P < 0.01). The findings indicate that age-related reduction in the accuracy of force control is associated with increased common fluctuations to motor neurons at low frequencies and not with an increase in independent synaptic input. NEW & NOTEWORTHY The influence of aging on the role of spinal motor neurons in accurate force control is not yet understood. We demonstrate that aging is associated with increased oscillations in common input to motor neurons at low frequencies and with a decrease in the relative strength of gamma oscillations. These results demonstrate that the synaptic inputs to motor neurons change across the life span and contribute to a decline in force control.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Castronovo

Mrachacz-Kersting

Stevenson

et al. 2018

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…The window size was 15 s providing a resolution of 0.06 Hz. The dependent variable was the proportion of power in the 0-0.25 Hz and 0.25-0.5 Hz relative to the total power of the force signal from 0 to 2 Hz [Moon et al, 2014;Park et al, 2017Park et al, , 2019. Power was made relative to 2 Hz since approximately 95% of total power of the static force signal is located between 0 and 2 Hz.…”

Section: Power Spectrum Analysismentioning

confidence: 99%

“…Power spectral density (PSD) analysis was performed using the Welch algorithm according to procedures outlined in from previous studies [Lodha et al, 2013; Moon et al, 2014; Park, Casamento‐Moran, Yacoubi, & Christou, 2017]. The static force signals were down sampled from 2000 Hz to 1000 Hz and detrended to remove bias from the signal.…”

Section: Signal Processing and Data Reductionmentioning

confidence: 99%

Children with Autism Spectrum Disorder Show Impairments During Dynamic Versus Static Grip‐force Tracking

et al. 2020

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Impairments in visuomotor integration (VMI) may contribute to anomalous development of motor, as well as socialcommunicative, skills in children with autism spectrum disorder (ASD). However, it is relatively unknown whether VMI impairments are specific to children with ASD versus children with other neurodevelopmental disorders. As such, this study addressed the hypothesis that children with ASD, but not those in other clinical control groups, would show greater deficits in high-VMI dynamic grip-force tracking versus low-VMI static presentation. Seventy-nine children, aged 7-17 years, participated: 22 children with ASD, 17 children with fetal alcohol spectrum disorder (FASD), 18 children with Attention-Deficit Hyperactivity Disorder (ADHD), and 22 typically developing (TD) children. Two grip-force tracking conditions were examined: (1) a low-VMI condition (static visual target) and (2) a high-VMI condition (dynamic visual target). Low-frequency force oscillations <0.5 Hz during the visuomotor task were also examined. Twoway ANCOVAs were used to examine group x VMI and group x frequency effects (α = 0.05). Children with ASD showed a difficulty, above that seen in the ADHD/FASD groups, tracking dynamic, but not static, visual stimuli as compared to TD children. Low-frequency force oscillations <0.25 Hz were also significantly greater in the ASD versus the TD group. This study is the first to report VMI deficits during dynamic versus static grip-force tracking and increased proportion of force oscillations <0.25 Hz during visuomotor tracking in the ASD versus TD group. Dynamic VMI impairments may be a core psychophysiologic feature that could contribute to impaired development of motor and socialcommunicative skills in ASD.

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“…For instance, significant correlations between F CoV and CoV for motor unit discharge rate were found in younger individuals [ 7 ]. Collectively, low-frequency oscillations in force may be consequences of variability in a single motor unit’s firing rate or low-frequency oscillations in the neural drive to the muscle, commonly estimated by the cumulative spike trains or the rectified-and-smoothed EMG (rsEMG) [ 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Ankle Joint Angle Influences Relative Torque Fluctuation during Isometric Plantar Flexion

2023

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The purpose of this study was to investigate the influence of changes in muscle length on the torque fluctuations and on related oscillations in muscle activity during voluntary isometric contractions of ankle plantar flexor muscles. Eleven healthy individuals were asked to perform voluntary isometric contractions of ankle muscles at five different contraction intensities from 10% to 70% of maximum voluntary isometric contraction (MVIC) and at three different muscle lengths, implemented by changing the ankle joint angle (plantar flexion of 26°-shorter muscle length; plantar flexion of 10°-neutral muscle length; dorsiflexion of 3°-longer muscle length). Surface electromyogram (EMG) signals were recorded from the skin surface over the triceps surae muscles, and rectified-and-smoothed EMG (rsEMG) were estimated to assess the oscillations in muscle activity. The absolute torque fluctuations (quantified by the standard deviation) were significantly higher during moderate-to-high contractions at the longer muscle length. Absolute torque fluctuations were found to be a linear function of torque output regardless of muscle length. In contrast, the relative torque fluctuations (quantified by the coefficient of variation) were higher at the shorter muscle length. However, both absolute and relative oscillations in muscle activities remained relatively consistent at different ankle joint angles for all plantar flexors. These findings suggest that the torque steadiness may be affected by not only muscle activities, but also by muscle length-dependent mechanical properties. This study provides more insights that muscle mechanics should be considered when explaining the steadiness in force output.

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

Cited by 19 publications

References 61 publications

Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Decrease in force steadiness with aging is associated with increased power of the common but not independent input to motor neurons

Children with Autism Spectrum Disorder Show Impairments During Dynamic Versus Static Grip‐force Tracking

Ankle Joint Angle Influences Relative Torque Fluctuation during Isometric Plantar Flexion

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