Sensitivity of EMG-EMG coherence to detect the common oscillatory drive to hand muscles in young and older adults

Keenan, Kevin G.; Massey, William V.; Walters, James; Collins, Joseph D.

doi:10.1152/jn.01011.2011

Cited by 30 publications

(31 citation statements)

References 62 publications

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“…For example, surface EMG will not be as sensitive as single motor unit recordings (Keenan et al, 2012) and may be influenced by signal processing techniques such as filtering or rectification (Boonstra and Breakspear, 2012; Farina et al, 2013). Even so, a systematic difference in the sensitivity of EMG signals to beta-band drive across tasks seems an unlikely explanation for our results, especially given the low levels of force required and our use of the most appropriate signal processing methods (i.e., EMG rectification) under these conditions (Farina et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Beta Band Corticomuscular Drive Reflects Muscle Coordination Strategies

Reyes

Laine

Kutch

et al. 2017

Front. Comput. Neurosci.

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During force production, hand muscle activity is known to be coherent with activity in primary motor cortex, specifically in the beta-band (15–30 Hz) frequency range. It is not clear, however, if this coherence reflects the control strategy selected by the nervous system for a given task, or if it instead reflects an intrinsic property of cortico-spinal communication. Here, we measured corticomuscular and intermuscular coherence between muscles of index finger and thumb while a two-finger pinch grip of identical net force was applied to objects which were either stable (allowing synergistic activation of finger muscles) or unstable (requiring individuated finger control). We found that beta-band corticomuscular coherence with the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles, as well as their beta-band coherence with each other, was significantly reduced when individuated control of the thumb and index finger was required. We interpret these findings to show that beta-band coherence is reflective of a synergistic control strategy in which the cortex binds task-related motor neurons into functional units.

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Section: Discussionmentioning

confidence: 99%

Beta Band Corticomuscular Drive Reflects Muscle Coordination Strategies

Reyes

Laine

Kutch

et al. 2017

Front. Comput. Neurosci.

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“…Specifically, there is evidence that producing well-directed forces is problematic for older adults [7], [8], [9]. In addition, fluctuations in fingertip force magnitude during isometric force-matching tasks are frequently greater in older than young adults, with performance depending on the task performed [10], [11], the type of visual feedback provided [12], [13], and the muscles/joints used [13]. Importantly, the functional relevance of examining force fluctuations to evaluate hand function has been established in older adults [10], [14].…”

Section: Introductionmentioning

confidence: 99%

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Keenan

Massey

2012

PLoS ONE

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Mobile computing devices (e.g., smartphones and tablets) that have low-friction surfaces require well-directed fingertip forces of sufficient and precise magnitudes for proper use. Although general impairments in manual dexterity are well-documented in older adults, it is unclear how these sensorimotor impairments influence the ability of older adults to dexterously manipulate fixed, low-friction surfaces in particular. 21 young and 18 older (65+ yrs) adults produced maximal voluntary contractions (MVCs) and steady submaximal forces (2.5 and 10% MVC) with the fingertip of the index finger. A Teflon covered custom-molded splint was placed on the fingertip. A three-axis force sensor was covered with either Teflon or sandpaper to create low- and high-friction surfaces, respectively. Maximal downward forces (Fz) were similar (p = .135) for young and older adults, and decreased by 15% (p<.001) while pressing on Teflon compared to sandpaper. Fluctuations in Fz during the submaximal force-matching tasks were 2.45× greater (p<.001) for older adults than in young adults, and reached a maximum when older adults pressed against the Teflon surface while receiving visual feedback. These age-associated changes in motor performance are explained, in part, by altered muscle activity from three hand muscles and out-of-plane forces. Quantifying the ability to produce steady fingertip forces against low-friction surfaces may be a better indicator of impairment and disability than the current practice of evaluating maximal forces with pinch meters. These age-associated impairments in dexterity while interacting with low-friction surfaces may limit the use of the current generation of computing interfaces by older adults.

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“…The level of sEMG-sEMG coherence between two synergistic muscles, which stems from the common oscillatory synaptic inputs to ␣-motoneurons, also varies according to the sEMG recording site over the hand muscles (Keenan et al 2011(Keenan et al , 2012. Therefore, it is expected that the sEMG recording site would influence the level of CMC and thus the reliability of cortical source estimation, important for functional mapping of the rolandic cortex.…”

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confidence: 99%

Spatial variability in cortex-muscle coherence investigated with magnetoencephalography and high-density surface electromyography

Piitulainen

Botter

Bourguignon

et al. 2015

Journal of Neurophysiology

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muscle coherence (CMC) reflects coupling between magnetoencephalography (MEG) and surface electromyography (sEMG), being strongest during isometric contraction but absent, for unknown reasons, in some individuals. We used a novel nonmagnetic high-density sEMG (HD-sEMG) electrode grid (36 mm ϫ 12 mm; 60 electrodes separated by 3 mm) to study effects of sEMG recording site, electrode derivation, and rectification on the strength of CMC. Monopolar sEMG from right thenar and 306-channel whole-scalp MEG were recorded from 14 subjects during 4-min isometric thumb abduction. CMC was computed for 60 monopolar, 55 bipolar, and 32 Laplacian HD-sEMG derivations, and two derivations were computed to mimic "macroscopic" monopolar and bipolar sEMG (electrode diameter 9 mm; interelectrode distance 21 mm). With unrectified sEMG, 12 subjects showed statistically significant CMC in 91-95% of the HD-sEMG channels, with maximum coherence at ϳ25 Hz. CMC was about a fifth stronger for monopolar than bipolar and Laplacian derivations. Monopolar derivations resulted in most uniform CMC distributions across the thenar and in tightest cortical source clusters in the left rolandic hand area. CMC was 19 -27% stronger for HD-sEMG than for "macroscopic" monopolar or bipolar derivations. EMG rectification reduced the CMC peak by a quarter, resulted in a more uniformly distributed CMC across the thenar, and provided more tightly clustered cortical sources than unrectifed sEMGs. Moreover, it revealed CMC at ϳ12 Hz. We conclude that HD-sEMG, especially with monopolar derivation, can facilitate detection of CMC and that individual muscle anatomy cannot explain the high interindividual CMC variability.

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Sensitivity of EMG-EMG coherence to detect the common oscillatory drive to hand muscles in young and older adults

Abstract: Keenan KG, Massey WV, Walters TJ, Collins JD. Sensitivity of EMG-EMG coherence to detect the common oscillatory drive to hand muscles in young and older adults.

Cited by 30 publications

References 62 publications

Beta Band Corticomuscular Drive Reflects Muscle Coordination Strategies

Beta Band Corticomuscular Drive Reflects Muscle Coordination Strategies

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Spatial variability in cortex-muscle coherence investigated with magnetoencephalography and high-density surface electromyography

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