Reflex Responses Induced by Tooth Unloading

The reflex response of the masseter muscle to the rapid unloading of a single maxillary incisor tooth was studied. Unloading of a static force of 2 N in the horizontal direction resulted in a short-latency excitation, inhibition, and long-latency excitation of masseter muscle activity occurring at latencies of approximately 13, 20, and 40 ms, respectively, with a corresponding change in bite force occurring slightly later in each case. Following the blocking of periodontal input by the injection of local anesthetic around the stimulated tooth, inhibitory responses were abolished. Therefore, it is concluded that the observed masseteric inhibition was caused by the unloading of periodontal mechanoreceptors and thus that these receptors may contribute to the jaw unloading reflex.

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Jaw Reflexes Evoked by Mechanical Stimulation of Teeth in Humans

Journal of Neurophysiology ◽

10.1152/jn.1999.81.5.2156 ◽

1999 ◽

Vol 81 (5) ◽

pp. 2156-2163 ◽

Cited By ~ 20

Author(s):

J. Yang ◽

K. S. Türker

Keyword(s):

Mechanical Stimulation ◽

Masseter Muscle ◽

Response Pattern ◽

Bite Force ◽

Reflex Response ◽

Incisor Tooth ◽

Jaw Muscles ◽

Reflex Responses ◽

Closing Force ◽

Stimulation Of

Jaw reflexes evoked by mechanical stimulation of teeth in humans. The reflex response of jaw muscles to mechanical stimulation of an upper incisor tooth was investigated using the surface electromyogram (SEMG) of the masseter muscle and the bite force. With a slowly rising stimulus, the reflex response obtained on the masseter SEMG showed three different patterns of reflex responses; sole excitation, sole inhibition, and inhibition followed by excitation. Simultaneously recorded bite force, however, exhibited mainly one reflex response pattern, a decrease followed by an increase in the net closing force. A rapidly rising stimulus also induced several different patterns of reflex responses in the masseter SEMG. When the simultaneously recorded bite force was analyzed, however, there was only one reflex response pattern, a decrease in the net closing force. Therefore, the reflex change in the masseter muscle is not a good representative of the net reflex response of all jaw muscles to mechanical tooth stimulation. The net response is best expressed by the averaged bite force. The averaged bite force records showed that when the stimulus force was developing rapidly, the periodontal reflex could reduce the bite force and hence protect the teeth and supporting tissues from damaging forces. It also can increase the bite force; this might help keep food between the teeth if the change in force rate is slow, especially when the initial bite force is low.

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Association Between Masseter Muscle Activity Levels Recorded During Sleep and Signs and Symptoms of Temporomandibular Disorders in Healthy Young Adults

Yearbook of Dentistry ◽

10.1016/s0084-3717(08)70511-7 ◽

2007 ◽

Vol 2007 ◽

pp. 269-270

Author(s):

R. Ohrbach

Keyword(s):

Young Adults ◽

Muscle Activity ◽

Temporomandibular Disorders ◽

Masseter Muscle ◽

Signs And Symptoms ◽

Activity Levels

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Roles played by histamine in strenuous or prolonged masseter muscle activity in mice

Clinical and Experimental Pharmacology and Physiology ◽

10.1111/1440-1681.12167 ◽

2013 ◽

Vol 40 (12) ◽

pp. 848-855 ◽

Cited By ~ 8

Author(s):

Hiroyuki Yoneda ◽

Fukie Niijima-Yaoita ◽

Masahiro Tsuchiya ◽

Hiroyuki Kumamoto ◽

Makoto Watanbe ◽

...

Keyword(s):

Muscle Activity ◽

Masseter Muscle

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Influence of the behavioral goal and environmental obstacles on rapid feedback responses

Journal of Neurophysiology ◽

10.1152/jn.01089.2011 ◽

2012 ◽

Vol 108 (4) ◽

pp. 999-1009 ◽

Cited By ~ 67

Author(s):

Joseph Y. Nashed ◽

Frédéric Crevecoeur ◽

Stephen H. Scott

Keyword(s):

Muscle Activity ◽

Motor System ◽

Optimal Feedback Control ◽

Motor Responses ◽

Spatial Properties ◽

Long Latency ◽

Circular Target ◽

Motor Actions ◽

Behavioral Goal ◽

Feedback Responses

The motor system must consider a variety of environmental factors when executing voluntary motor actions, such as the shape of the goal or the possible presence of intervening obstacles. It remains unknown whether rapid feedback responses to mechanical perturbations also consider these factors. Our first experiment quantified how feedback corrections were altered by target shape, which was either a circular dot or a bar. Unperturbed movements to each target were qualitatively similar on average but with greater dispersion of end point positions when reaching to the bar. On random trials, multijoint torque perturbations deviated the hand left or right. When reaching to a circular target, perturbations elicited corrective movements that were directed straight to the location of the target. In contrast, corrective movements when reaching to a bar were redirected to other locations along the bar axis. Our second experiment quantified whether the presence of obstacles could interfere with feedback corrections. We found that hand trajectories after the perturbations were altered to avoid obstacles in the environment. Importantly, changes in muscle activity reflecting the different target shapes (bar vs. dot) or the presence of obstacles were observed in as little as 70 ms. Such changes in motor responses were qualitatively consistent with simulations based on optimal feedback control. Taken together, these results highlight that long-latency motor responses consider spatial properties of the goal and environment.

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Long-latency, inhibitory spinal pathway to ankle flexors activated by homonymous group 1 afferents

Journal of Neurophysiology ◽

10.1152/jn.00673.2013 ◽

2014 ◽

Vol 111 (12) ◽

pp. 2544-2553 ◽

Cited By ~ 5

Author(s):

Ephrem T. Zewdie ◽

Francois D. Roy ◽

Yoshino Okuma ◽

Jaynie F. Yang ◽

Monica A. Gorassini

Keyword(s):

Muscle Activity ◽

Corticospinal Tract ◽

Inhibitory Pathway ◽

Thoracic Spinal Cord ◽

Thoracic Spinal ◽

Long Latency ◽

Inhibitory Feedback ◽

Spinal Pathway ◽

Low Threshold ◽

Pulse Stimulation

Inhibitory feedback from sensory pathways is important for controlling movement. Here, we characterize, for the first time, a long-latency, inhibitory spinal pathway to ankle flexors that is activated by low-threshold homonymous afferents. To examine this inhibitory pathway in uninjured, healthy participants, we suppressed motor-evoked potentials (MEPs), produced in the tibialis anterior (TA), by a prior stimulation to the homonymous common peroneal nerve (CPN). The TA MEP was suppressed by a triple-pulse stimulation to the CPN, applied 40, 50, and 60 ms earlier and at intensities of 0.5–0.7 times motor threshold (average suppression of test MEP was 33%). Whereas the triple-pulse stimulation was below M-wave and H-reflex threshold, it produced a long-latency inhibition of background muscle activity, approximately 65–115 ms after the CPN stimulation, a time period that overlapped with the test MEP. However, not all of the MEP suppression could be accounted for by this decrease in background muscle activity. Evoked responses from direct activation of the corticospinal tract, at the level of the brain stem or thoracic spinal cord, were also suppressed by low-threshold CPN stimulation. Our findings suggest that low-threshold muscle and cutaneous afferents from the CPN activate a long-latency, homonymous spinal inhibitory pathway to TA motoneurons. We propose that inhibitory feedback from spinal networks, activated by low-threshold homonymous afferents, helps regulate the activation of flexor motoneurons by the corticospinal tract.

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Effects of orthodontic archwire changes on masseter muscle activity

American Journal of Orthodontics ◽

10.1016/0002-9416(84)90154-4 ◽

1984 ◽

Vol 86 (4) ◽

pp. 353 ◽

Cited By ~ 1

Author(s):

B.R. Smith ◽

C.M. Flanary ◽

C.L. Hurst ◽

J.D. Rugh

Keyword(s):

Muscle Activity ◽

Masseter Muscle

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Motor learning and transfer: from feedback to feedforward control

10.1101/845933 ◽

2019 ◽

Author(s):

Rodrigo S. Maeda ◽

Paul L. Gribble ◽

J. Andrew Pruszynski

Keyword(s):

Motor Learning ◽

Muscle Activity ◽

Shoulder Joint ◽

Stretch Reflex ◽

Feedforward Control ◽

Motor Task ◽

Joint Torques ◽

Motor Commands ◽

Shoulder Muscle ◽

Long Latency

AbstractPrevious work has demonstrated that when learning a new motor task, the nervous system modifies feedforward (ie. voluntary) motor commands and that such learning transfers to fast feedback (ie. reflex) responses evoked by mechanical perturbations. Here we show the inverse, that learning new feedback responses transfers to feedforward motor commands. Sixty human participants (34 females) used a robotic exoskeleton and either 1) received short duration mechanical perturbations (20 ms) that created pure elbow rotation or 2) generated self-initiated pure elbow rotations. They did so with the shoulder joint free to rotate (normal arm dynamics) or locked (altered arm dynamics) by the robotic manipulandum. With the shoulder unlocked, the perturbation evoked clear shoulder muscle activity in the long-latency stretch reflex epoch (50-100ms post-perturbation), as required for countering the imposed joint torques, but little muscle activity thereafter in the so-called voluntary response. After locking the shoulder joint, which alters the required joint torques to counter pure elbow rotation, we found a reliable reduction in the long-latency stretch reflex over many trials. This reduction transferred to feedforward control as we observed 1) a reduction in shoulder muscle activity during self-initiated pure elbow rotation trials and 2) kinematic errors (ie. aftereffects) in the direction predicted when failing to compensate for normal arm dynamics, even though participants never practiced self-initiated movements with the shoulder locked. Taken together, our work shows that transfer between feedforward and feedback control is bidirectional, furthering the notion that these processes share common neural circuits that underlie motor learning and transfer.

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The power features of Masseter muscle activity in tension-type and migraine without aura headache during open-close clench cycles

PeerJ ◽

10.7717/peerj.3556 ◽

2017 ◽

Vol 5 ◽

pp. e3556 ◽

Cited By ~ 1

Author(s):

Behrouz Alizadeh Savareh ◽

Ali Ghanjal ◽

Azadeh Bashiri ◽

Monireh Motaqhey ◽

Boshra Hatef

Keyword(s):

Muscle Activity ◽

Masseter Muscle ◽

Migraine Without Aura ◽

Mouth Opening ◽

Tension Type Headache ◽

Emg Activity ◽

Statistical Parameters ◽

Signal Energy ◽

Type Headache ◽

Mean Variance

Introduction Different types of headaches and TMJ click influence the masseter muscle activity. The aim of this study was to assess the trend of energy level of the electromyography (EMG) activity of the masseter muscle during open-close clench cycles in migraine without aura (MOA) and tension-type headache (TTH) with or without TMJ click. Methods Twenty-five women with MOA and twenty four women with TTH participated in the study. They matched with 25 healthy subjects, in terms of class of occlusion and prevalence of temporomandibular joint (TMJ) with click. The EMG of both masseter muscles were recorded during open-close clench cycles at a rate of 80 cycles per minute for 15 seconds. The mouth opening was restricted to two centimeters by mandibular motion frame. Signal processing steps have been done on the EMG as: noise removing, smoothing, feature extraction, and statistical analyzing. The six statistical parameters of energy computed were mean, Variance, Skewness, Kurtosis, and first and second half energy over all signal energy. Results A three-way ANOVA indicated that during all the cycles, the mean of energy was more and there was a delay in showing the peak of energy in the masseter of the left side with clicked TMJ in MOA group compared to the two other groups, while this pattern occurred inversely in the side with no-clicked TMJ (P < 0.009). The variation of energy was significantly less in MOA group compared to the two other groups in the no-clicked TMJ (P < 0.003). However, the proportion of the first or second part of signal energy to all energy showed that TTH group had less energy in the first part and more energy in the second part in comparison to the two other groups (P < 0.05). Conclusion The study showed different changes in the energy distribution of masseter muscle activity during cycles in MOA and TTH. MOA, in contrast to TTH, had lateralization effect on EMG and interacted with TMJ click.

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