Task-Specific Organization of Activity in Human Jaw Muscles

1988 ◽  
Vol 31 (4) ◽  
pp. 670-680 ◽  
Author(s):  
Christopher A. Moore ◽  
Anne Smith ◽  
Robert L. Ringel
Keyword(s):  
Speech Production ◽  
Muscle Activity ◽  
Pattern Generator ◽  
Task Demands ◽  
Emg Activity ◽  
Muscle Synergies ◽  
Mandibular Movement ◽  
Jaw Muscles ◽  
Activation Patterns ◽  
Jaw Muscle

Coordination of jaw muscle activity for speech production sometimes has been modeled using nonspeech behaviors. This orientation has been especially true in representations of mandibular movement in which the synergy of jaw muscles for speech production has been suggested to be derived from the central pattern generator (CPG) for chewing. The present investigation compared the coordination of EMG activity in mandibular muscles over a range of speech and nonspeech tasks. Results of a cross-correlational analysis between EMG signals demonstrated that the muscle synergies of the mandibular system depend on task demands. Contrary to some of the models discussed, continuous speech production yielded activation patterns that were clearly not related to coordinative patterns generated by the chewing CPG.

scholarly journals Changes in Locomotor Muscle Activity After Treadmill Training in Subjects With Incomplete Spinal Cord Injury

2009 ◽  
Vol 101 (2) ◽  
pp. 969-979 ◽  
Author(s):  
Monica A. Gorassini ◽  
Jonathan A. Norton ◽  
Jennifer Nevett-Duchcherer ◽  
Francois D. Roy ◽  
Jaynie F. Yang
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Treadmill Training ◽  
Emg Activity ◽  
Incomplete Spinal Cord Injury ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Cord Injury

Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.

Characteristics of Glutamate-Evoked Temporomandibular Joint Afferent Activity in the Rat

2001 ◽  
Vol 85 (6) ◽  
pp. 2446-2454 ◽  
Author(s):  
Brian E. Cairns ◽  
Barry J. Sessle ◽  
James W. Hu
Keyword(s):  
Temporomandibular Joint ◽  
Receptive Fields ◽  
Male Rats ◽  
Emg Activity ◽  
Digastric Muscle ◽  
Afferent Activity ◽  
Jaw Muscles ◽  
M 10 ◽  
Jaw Muscle ◽  
Evoked Activity

Injection of glutamate into the rat temporomandibular joint (TMJ) capsule can reflexly induce a prolonged increase in the electromyographic (EMG) activity of the jaw muscles, however, the characteristics of TMJ afferents activated by glutamate have not been investigated. In the present study, we examined the effect of glutamate injection into the TMJ capsule on jaw muscle EMG activity and the extracellularly recorded activity of single trigeminal afferents that had receptive fields in the TMJ tissue and antidromically identified projections to the brain stem subnucleus caudalis (Vc) in rats of both sexes. Glutamate (0.05–1.0 M, 10 μl) injection into the TMJ capsule evoked EMG activity in a dose-related manner; however, at concentrations of 0.5 and 1.0 M, glutamate-evoked digastric muscle responses were greater in female than in male rats. In experiments where jaw muscle EMG and afferent activity were recorded simultaneously, glutamate (0.5 M, 10 μl) injection into the TMJ capsule evoked activity in the jaw muscles as well as in 27 (26 Aδ and 1 C-fiber afferent) of 34 trigeminal afferents that could be activated by blunt mechanical stimulation of the TMJ tissue. In these experiments, glutamate-evoked jaw muscle activity was significantly increased for 6 min after the glutamate injection, whereas afferent activity was significantly increased only during the first minute after the glutamate injection. The glutamate-evoked afferent activity was inversely related to conduction velocity and, in afferents with conduction velocities <10 m/s, was significantly greater in female ( n = 6) than in male ( n = 10) rats. These results suggest that glutamate excites putative nociceptive afferents within the TMJ to a greater degree in female than in male rats. This sex-related difference in afferent discharge may, in part, underlie sex-related differences in glutamate-evoked jaw muscle EMG activity.

Activation of Peripheral GABAA Receptors Inhibits Temporomandibular Joint–Evoked Jaw Muscle Activity

1999 ◽  
Vol 81 (4) ◽  
pp. 1966-1969 ◽  
Author(s):  
Brian E. Cairns ◽  
Barry J. Sessle ◽  
James W. Hu
Keyword(s):  
Receptor Antagonist ◽  
Temporomandibular Joint ◽  
Gabaa Receptors ◽  
Muscle Activity ◽  
Mustard Oil ◽  
Emg Activity ◽  
Dose Response Relationship ◽  
Jaw Muscle ◽  
Nociceptive Information ◽  
Masseter Muscles

Activation of peripheral GABAA receptors inhibits temporomandibular joint–evoked jaw muscle activity. We have previously shown that injection of mustard oil or glutamate into rat temporomandibular joint (TMJ) tissues, an experimental model of acute TMJ injury, can reflexly induce a prolonged increase in the activity of both digastric (jaw-opener) and masseter (jaw-closer) muscles. In this study, GABA was applied to the TMJ region by itself or in combination with glutamate, and the magnitude of evoked jaw muscle electromyographic (EMG) activity was measured. Application of GABA alone to the TMJ region did not evoke significant jaw muscle EMG activity when compared with normal saline controls. In contrast, co-application of GABA and glutamate into the TMJ region decreased the magnitude of glutamate-evoked EMG activity. This GABA-mediated inhibition of glutamate-evoked EMG activity followed an inverse dose-response relationship with an estimated median inhibitory dose (ID50) of 0.17 ± 0.05 (SE) μmol and 0.031 ± 0.006 μmol for the digastric and masseter muscles, respectively. Co-administration of the GABAA receptor antagonist bicuculline (0.05 μmol) but not the GABABreceptor antagonist phaclofen (0.05 or 0.15 μmol) reversed the suppressive actions of GABA, indicating that this action of GABA may be mediated by peripheral GABAA receptors located within the TMJ region. Our results suggest that activation of peripheral GABAA receptors located within the TMJ region could act to decrease the transmission of nociceptive information.

scholarly journals Functional connectivity in neuromuscular system underlying bimanual muscle synergies

2016 ◽  
Author(s):  
Ingmar E. J. de Vries ◽  
Andreas Daffertshofer ◽  
Dick F. Stegeman ◽  
Tjeerd W. Boonstra
Keyword(s):  
Functional Connectivity ◽  
Muscle Activity ◽  
Uncontrolled Manifold ◽  
Emg Activity ◽  
Muscle Synergies ◽  
Neural Pathways ◽  
Beta Band ◽  
Corticomuscular Coherence ◽  
Intermuscular Coherence ◽  
High Coordination

AbstractNeural synchrony has been suggested as mechanism for integrating distributed sensorimotor systems involved in coordinated movement. To test the role of corticomuscular and intermuscular coherence in the formation of bimanual muscle synergies, we experimentally manipulated the degree of coordination between hand muscles by varying the sensitivity of the visual feedback to differences in bilateral force. In 16 healthy participants, cortical activity was measured using 64-channel electroencephalography (EEG) and muscle activity of the flexor pollicis brevis muscle of both hands using 8×8-channel high-density electromyography (HDsEMG). Using the uncontrolled manifold framework, coordination between bilateral forces was quantified by the synergy index RV in the time and frequency domain. Functional connectivity was assed using corticomuscular coherence between muscle activity and cortical source activity and intermuscular coherence between bilateral EMG activity. As expected, bimanual synergies were stronger in the high coordination condition. RV was higher in the high coordination condition in frequencies between 0 and 0.5 Hz, and above 2 Hz. For the 0.5-2 Hz frequency band this pattern was inverted. Corticomuscular coherence in the beta band (16-30 Hz) was maximal in the contralateral motor cortex and was reduced in the high coordination condition. In contrast, intermuscular coherence was observed at 5-12 Hz and increased with bimanual coordination. Within-subject comparisons revealed a negative correlation between RV and corticomuscular coherence and a positive correlation between RV and intermuscular coherence. Our findings suggest two distinct neural pathways: (1) Corticomuscular coherence reflects direct corticospinal projections involved in controlling individual muscles; (2) intermuscular coherence reflects diverging pathways involved in the coordination of multiple muscles.

scholarly journals Vision fine-tunes preparation for landing in the cane toad, Rhinella marina

2018 ◽  
Vol 14 (9) ◽  
pp. 20180397 ◽  
Author(s):  
Laura J. Ekstrom ◽  
Chris Panzini ◽  
Gary B. Gillis
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Fine Tuning ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Impact Forces ◽  
Before And After ◽  
The Impact

In toad hopping, the hindlimbs generate the propulsive force for take-off while the forelimbs resist the impact forces associated with landing. Preparing to perform a safe landing, in which impact forces are managed appropriately, likely involves the integration of multiple types of sensory feedback. In toads, vestibular and/or proprioceptive feedback is critical for coordinated landing; however, the role of vision remains unclear. To clarify this, we compare pre-landing forelimb muscle activation patterns before and after removing vision. Specifically, we recorded EMG activity from two antagonistic forelimb muscles, the anconeus and coracoradialis, which demonstrate distance-dependent onset timing and recruitment intensity, respectively. Toads were first recorded hopping normally and then again after their optic nerves were severed to remove visual feedback. When blind, toads exhibited hop kinematics and pre-landing muscle activity similar to when sighted. However, distance-dependent relationships for muscle activity patterns were more variable, if present at all. This study demonstrates that blind toads are still able to perform coordinated landings, reinforcing the importance of proprioceptive and/or vestibular feedback during hopping. But the increased variability in distance-dependent activity patterns indicates that vision is more responsible for fine-tuning the motor control strategy for landing.

EMG Activity within the Pharynx during Speech Production

1974 ◽  
Vol 17 (3) ◽  
pp. 497-504 ◽  
Author(s):  
Fred D. Minifie ◽  
James H. Abbs ◽  
Arlene Tarlow ◽  
Mitchell Kwaterski
Keyword(s):  
Speech Production ◽  
Muscle Activity ◽  
Active Role ◽  
Emg Activity ◽  
Stop Consonants ◽  
Vowel Production

Electromyography (EMG) of the superior and middle constrictor muscles was recorded during phonated and whispered productions of the vowels /i/ and /a/ and the stop consonants /p/ and /b/ in VCVCV trisyllables. Lower levels of EMG activity were consistently associated with production of the voiced consonant /b/ than with comparable productions of the voiceless consonant /p/. Larger amplitude EMG signals were associated with vowel production than with consonant production. No systematic differences in muscle activity were observed as a function of phonated VS whispered productions. These findings are interpreted in relation to the active role of the pharynx during speech production.

scholarly journals Correlation between jaw muscle activity and bite force under the known different craniofacial form. Part 1. Classification of craniofacial form and it's influence on jaw muscles activity and bite force.

1988 ◽  
Vol 32 (6) ◽  
pp. 1378-1385 ◽  
Author(s):  
Nobuhito Gionhaku ◽  
Toshimitsu Iinuma ◽  
Kenichi Izumi ◽  
Masatoshi Shimizu ◽  
Yutaka Kawamura ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Bite Force ◽  
Jaw Muscles ◽  
Jaw Muscle ◽  
Form Part

scholarly journals Task-level feedback can explain temporal recruitment of spatially fixed muscle synergies throughout postural perturbations

2012 ◽  
Vol 107 (1) ◽  
pp. 159-177 ◽  
Author(s):  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Muscle Activity ◽  
Neural Control ◽  
Temporal Patterns ◽  
Emg Activity ◽  
Muscle Synergies ◽  
Muscle Coordination ◽  
Postural Responses ◽  
Temporal Features ◽  
Low Dimensional ◽  
Task Level

Recent evidence suggests that complex spatiotemporal patterns of muscle activity can be explained with a low-dimensional set of muscle synergies or M-modes. While it is clear that both spatial and temporal aspects of muscle coordination may be low dimensional, constraints on spatial versus temporal features of muscle coordination likely involve different neural control mechanisms. We hypothesized that the low-dimensional spatial and temporal features of muscle coordination are independent of each other. We further hypothesized that in reactive feedback tasks, spatially fixed muscle coordination patterns—or muscle synergies—are hierarchically recruited via time-varying neural commands based on delayed task-level feedback. We explicitly compared the ability of spatially fixed (SF) versus temporally fixed (TF) muscle synergies to reconstruct the entire time course of muscle activity during postural responses to anterior-posterior support-surface translations. While both SF and TF muscle synergies could account for EMG variability in a postural task, SF muscle synergies produced more consistent and physiologically interpretable results than TF muscle synergies during postural responses to perturbations. Moreover, a majority of SF muscle synergies were consistent in structure when extracted from epochs throughout postural responses. Temporal patterns of SF muscle synergy recruitment were well-reconstructed by delayed feedback of center of mass (CoM) kinematics and reproduced EMG activity of multiple muscles. Consistent with the idea that independent and hierarchical low-dimensional neural control structures define spatial and temporal patterns of muscle activity, our results suggest that CoM kinematics are a task variable used to recruit SF muscle synergies for feedback control of balance.

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