Mechanical properties of single motor units in the anterior belly of the digastric

1977 ◽  
Vol 62 (S1) ◽  
pp. S15-S15
Author(s):  
Peter F. MacNeilage ◽  
H. M. Sussman ◽  
R. K. Powers ◽  
J. R. Westbury
Keyword(s):  
Mechanical Properties ◽  
Motor Units ◽  
Single Motor ◽  
Single Motor Units ◽  
Anterior Belly

Recruitment and Discharge Patterns of Single Motor Units During Speech Production

1977 ◽  
Vol 20 (4) ◽  
pp. 613-630 ◽  
Author(s):  
Harvey M. Sussman ◽  
Peter F. MacNeilage ◽  
Randall K. Powers
Keyword(s):  
Dynamic Range ◽  
Isometric Force ◽  
Discharge Rate ◽  
Motor Units ◽  
Size Principle ◽  
Single Motor ◽  
Single Motor Units ◽  
Movement Dynamics ◽  
Discharge Patterns ◽  
Anterior Belly

Recruitment and discharge patterns of single motor units (MUs) in the anterior belly of digastric were studied during speech in three subjects, using electrodes facilitating selective recording at high force levels. Fixed recruitment order was observed in over 99% of all comparisons. Later recruited units invariably possessed muscle action potentials of higher amplitude, suggesting that units were activated in accordance with the “size principle.” Additional evidence for this was that later recruited units, of a set of three studied during speech, motor unit training, and isometric force ramps, showed greater sensitivity to input, and greater dynamic range than earlier recruited units. Units in this set were much more sensitive to rapid changes in input associated with speech gestures than to static activation even at high force levels. Several significant relations between discharge characteristics and aspects of movement dynamics were observed, including relations between (1) recruitment interval (MU1 to MU3) and latency of mandibular lowering, (2) onset of initial discharge of MU1 and relative mechanical advantage of the mandible, (3) number of MUs active and velocity and displacement of the mandible, and (4) discharge rate of MU3 and velocity and displacement of the mandible.

Mechanical properties of single motor units in speech musculature

1979 ◽  
Vol 65 (4) ◽  
pp. 1047-1052 ◽  
Author(s):  
Peter F. MacNeilage ◽  
Harvey M. Sussman ◽  
John R. Westbury ◽  
Randall K. Powers
Keyword(s):  
Mechanical Properties ◽  
Motor Units ◽  
Single Motor ◽  
Single Motor Units

Reduced control of motor output in a human hand muscle of elderly subjects during submaximal contractions

1993 ◽  
Vol 69 (6) ◽  
pp. 2108-2115 ◽  
Author(s):  
M. E. Galganski ◽  
A. J. Fuglevand ◽  
R. M. Enoka
Keyword(s):  
Mechanical Properties ◽  
Motor Units ◽  
Motor Output ◽  
Elderly Subjects ◽  
Control Force ◽  
Constant Force ◽  
Single Motor ◽  
Single Motor Units ◽  
Discharge Behavior ◽  
Effect Of Age

1. The effect of age on the motor output of the first dorsal interosseous muscle of 22 (6 female, 16 male) human subjects was investigated. The purpose of the study was to determine the effect of age on the control of muscle force and the associated changes in the discharge behavior and mechanical properties of single motor units. 2. Each subject performed three tasks requiring isometric abduction of the left index finger: a maximum voluntary contraction (MVC), a constant-force task, and a threshold task. The ability to control force was assessed during the constant-force task by quantifying the variation in isometric force about four submaximal target forces (5, 20, 35, and 50% MVC). The threshold task involved sustaining the discharge of the isolated motor unit at a low, steady rate for approximately 3 min. 3. The discharge behavior and the mechanical properties of single motor units were determined during the threshold task by measuring the interimpulse intervals and the peak amplitude and time to peak of the spike-triggered average force. 4. The data indicated that age had an effect on the variation of force about submaximal target forces (range: 5-50% MVC), and that these force variations, when calculated relative to the target force, were greater at lower force levels in the elderly subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Rectification is required to extract oscillatory envelope modulation from surface electromyographic signals

2014 ◽  
Vol 112 (7) ◽  
pp. 1685-1691 ◽  
Author(s):  
Christopher J. Dakin ◽  
Brian H. Dalton ◽  
Billy L. Luu ◽  
Jean-Sébastien Blouin
Keyword(s):  
Motor Unit ◽  
Stimulus Frequency ◽  
Motor Units ◽  
Surface Emg ◽  
Medial Gastrocnemius ◽  
Single Motor Unit ◽  
Single Motor ◽  
Single Motor Units ◽  
Emg Signal ◽  
Envelope Modulation

Rectification of surface electromyographic (EMG) recordings prior to their correlation with other signals is a widely used form of preprocessing. Recently this practice has come into question, elevating the subject of EMG rectification to a topic of much debate. Proponents for rectifying suggest it accentuates the EMG spike timing information, whereas opponents indicate it is unnecessary and its nonlinear distortion of data is potentially destructive. Here we examine the necessity of rectification on the extraction of muscle responses, but for the first time using a known oscillatory input to the muscle in the form of electrical vestibular stimulation. Participants were exposed to sinusoidal vestibular stimuli while surface and intramuscular EMG were recorded from the left medial gastrocnemius. We compared the unrectified and rectified surface EMG to single motor units to determine which method best identified stimulus-EMG coherence and phase at the single-motor unit level. Surface EMG modulation at the stimulus frequency was obvious in the unrectified surface EMG. However, this modulation was not identified by the fast Fourier transform, and therefore stimulus coherence with the unrectified EMG signal failed to capture this covariance. Both the rectified surface EMG and single motor units displayed significant coherence over the entire stimulus bandwidth (1–20 Hz). Furthermore, the stimulus-phase relationship for the rectified EMG and motor units shared a moderate correlation ( r = 0.56). These data indicate that rectification of surface EMG is a necessary step to extract EMG envelope modulation due to motor unit entrainment to a known stimulus.

Threshold variations of medial pterygoid single motor units during vertical or horizontal force tasks

2021 ◽  
Author(s):  
Yalda Nozad Mojaver ◽  
Paul Tawadros ◽  
Polyana Moura Ferreira ◽  
Terry Whittle ◽  
Greg M. Murray
Keyword(s):  
Motor Units ◽  
Horizontal Force ◽  
Single Motor ◽  
Single Motor Units ◽  
Medial Pterygoid
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