Interactions between the jaw-opening reflex and mastication

1981 ◽  
Vol 59 (7) ◽  
pp. 683-690 ◽  
Author(s):  
J. P. Lund ◽  
S. Rossignol ◽  
T. Murakami
Keyword(s):  
Muscle Activity ◽  
Control Period ◽  
Mean Amplitude ◽  
Reflex Response ◽  
Digastric Muscle ◽  
Dependent Manner ◽  
Excitatory Response ◽  
Jaw Opening ◽  
Jaw Opening Reflex ◽  
The Mean

Electrical stimulation of the anterior hard palate or upper lip was used to evoke the jaw-opening reflex in rabbits lightly anesthetized with urethane. The amplitude of each excitatory response recorded in the digastric electromyogram during mastication was compared with the mean amplitude of 10 prior control responses. When weak stimuli were used, the mean amplitude of the reflex dropped markedly during mastication and was smallest when the digastric muscle was inactive (closing and occlusal phases of the masticatory cycle). As the stimulus strength was increased, the size of the response during closing rose progressively until it exceeded values obtained during the control period or the jaw-opening phase.In addition, strong stimuli altered the total cycle length and the duration and amplitude of muscle activity in a phase-dependent manner. Stimuli given during closing were particularly effective in causing inhibition of jaw-closing muscle activity and in reducing the velocity and amplitude of closure.It is concluded that the cyclical gain changes of the reflex response to noxious stimuli are controlled to a large extent by premotoneuronal mechanisms and that the overall effect on the masticatory cycle structure is phase dependent.

Biting intentions modulate digastric reflex responses to sudden unloading of the jaw

2014 ◽  
Vol 112 (5) ◽  
pp. 1067-1073 ◽  
Author(s):  
Anders S. Johansson ◽  
J. Andrew Pruszynski ◽  
Benoni B. Edin ◽  
Karl-Gunnar Westberg
Keyword(s):  
Muscle Activity ◽  
Reflex Response ◽  
Digastric Muscle ◽  
Single Trial ◽  
Jaw Muscles ◽  
Muscle Response ◽  
Reflex Responses ◽  
Jaw Opening ◽  
Trial Basis ◽  
Study Participants

Reflex responses in jaw-opening muscles can be evoked when a brittle object cracks between the teeth and suddenly unloads the jaw. We hypothesized that this reflex response is flexible and, as such, is modulated according to the instructed goal of biting through an object. Study participants performed two different biting tasks when holding a peanut half stacked on a chocolate piece between their incisors. In one task, they were asked to split the peanut half only (single-split task), and in the other task, they were asked to split both the peanut and the chocolate in one action (double-split task). In both tasks, the peanut split evoked a jaw-opening muscle response, quantified from electromyogram (EMG) recordings of the digastric muscle in a window 20–60 ms following peanut split. Consistent with our hypothesis, we found that the jaw-opening muscle response in the single-split trials was about twice the size of the jaw-opening muscle response in the double-split trials. A linear model that predicted the jaw-opening muscle response on a single-trial basis indicated that task settings played a significant role in this modulation but also that the presplit digastric muscle activity contributed to the modulation. These findings demonstrate that, like reflex responses to mechanical perturbations in limb muscles, reflex responses in jaw muscles not only show gain-scaling but also are modulated by subject intent.

Behavior of Jaw Muscle Spindle Afferents During Cortically Induced Rhythmic Jaw Movements in the Anesthetized Rabbit

1999 ◽  
Vol 82 (5) ◽  
pp. 2633-2640 ◽  
Author(s):  
O. Hidaka ◽  
T. Morimoto ◽  
T. Kato ◽  
Y. Masuda ◽  
T. Inoue ◽  
...  
Keyword(s):  
Firing Rate ◽  
Muscle Spindle ◽  
Muscle Activity ◽  
Muscle Spindles ◽  
Emg Activity ◽  
Spatiotemporal Pattern ◽  
Digastric Muscle ◽  
Dependent Manner ◽  
Jaw Movements ◽  
Jaw Opening

The regulation by muscle spindles of jaw-closing muscle activity during mastication was evaluated in anesthetized rabbits. Simultaneous records were made of the discharges of muscle spindle units in the mesencephalic trigeminal nucleus, masseter and digastric muscle activity (electromyogram [EMG]), and jaw-movement parameters during cortically induced rhythmic jaw movements. One of three test strips of polyurethane foam, each of a different hardness, was inserted between the opposing molars during the jaw movements. The induced rhythmic jaw movements were crescent shaped and were divided into three phases: jaw-opening, jaw-closing, and power. The firing rate of muscle spindle units during each phase increased after strip application, with a tendency for the spindle discharge to be continuous throughout the entire chewing cycle. However, although the firing rate did not change during the jaw-opening and jaw-closing phases when the strip hardness was altered, the firing rate during the power phase increased in a hardness-dependent manner. In addition, the integrated EMG activity, the duration of the masseteric bursts, and the minimum gape increased with strip hardness. Spindle discharge during the power phase correlated with jaw-closing muscle activity, implying that the change in jaw-closing muscle activity associated with strip hardness was caused by increased spindle discharge produced through insertion of a test strip. The increased firing rate during the other two phases may be involved in a long-latency spindle feedback. This could contribute to matching the spatiotemporal pattern of the central pattern generator to that of the moving jaw.

scholarly journals Low-Frequency Oscillations (<0.3 Hz) in the Electromyographic (EMG) Activity of the Human Trapezius Muscle During Sleep

2002 ◽  
Vol 88 (3) ◽  
pp. 1177-1184 ◽  
Author(s):  
R. H. Westgaard ◽  
P. Bonato ◽  
K. A. Holte
Keyword(s):  
Heart Rate ◽  
Muscle Activity ◽  
Activity Pattern ◽  
Sudden Change ◽  
Mean Amplitude ◽  
Activity Level ◽  
Emg Activity ◽  
Similar Frequency ◽  
Emg Signal ◽  
The Mean

The surface electromyographic (EMG) signal from right and left trapezius muscles and the heart rate were recorded over 24 h in 27 healthy female subjects. The root-mean-square (RMS) value of the surface EMG signals and the heartbeat interval time series were calculated with a time resolution of 0.2 s. The EMG activity during sleep showed long periods with stable mean amplitude, modulated by rhythmic components in the frequency range 0.05–0.2 Hz. The ratio between the amplitude of the oscillatory components and the mean amplitude of the EMG signal was approximately constant over the range within which the phenomenon was observed, corresponding to a peak-to-peak oscillatory amplitude of ∼10% of the mean amplitude. The duration of the periods with stable mean amplitude ranged from a few minutes to ∼1 h, usually interrupted by a sudden change in the activity level or by cessation of the muscle activity. Right and left trapezius muscles presented the same pattern of FM. In supplementary experiments, rhythmic muscle activity pattern was also demonstrated in the upper extremity muscles of deltoid, biceps, and forearm flexor muscles. There was no apparent association between the rhythmic components in the muscle activity pattern and the heart rate variability. To our knowledge, this is the first time that the above-described pattern of EMG activity during sleep is documented. On reanalysis of earlier recorded trapezius motor unit firing pattern in experiments on awake subjects in a situation with mental stress, low-FM of firing with similar frequency content was detected. Possible sources of rhythmic excitation of trapezius motoneurons include slow-wave cortical oscillations represented in descending cortico-spinal pathways, and/or activation by monoaminergic pathways originating in the brain stem reticular formation. The analysis of muscle activity patterns may provide an important new tool to study neural mechanisms in human sleep.

scholarly journals Use of medetomidine, midazolam, ketamine and sevoflurane as an anesthetic protocol for domestic chickens

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Yıldırım Çelik ◽  
Gültekin Atalan ◽  
Vehbi Güneş ◽  
Umut Alpman ◽  
Muhammed Kaan Yönez
Keyword(s):  
Biochemical Parameters ◽  
Mean Amplitude ◽  
P Wave ◽  
Reflex Response ◽  
Time Intervals ◽  
Life Threatening ◽  
Baseline Values ◽  
The Mean ◽  
Electrocardiogram Ecg ◽  
Anesthesia Time

Changes in physiological and biochemical parameters after administration of medetomidine (MED), midazolam (MID), ketamine (KET) and a 2% of the inhalation anesthetic sevoflurane (SEVO), were investigated in domestic chickens. The anesthetic protocol began with a simultaneous intrapectoral injection (IP) of MED (50 μg/kg) and MID (0.5 mg/kg), followed by IP administration of 25 mg/kg of KET 10 min later. Anesthesia was then maintained for 30 min by 2% SEVO (with a 500 ml/min oxygen flow), using an Ayres T piece device. Heart and respiratory rates, cloacal temperature, reflex response and electrocardiogram (ECG) parameters were recorded at time cero (T0) before anesthesia (BA, baseline values), at time of MED+MID administration (T1), at time of ketamine injection (T2), 30 min after the start of SEVO inhalation (T3) and at recovery. Blood was also drawn at T0 and T3 to assess albumin, creatinine, glucose and liver enzyme concentrations. Cloacal temperature, heart and respiratory rates differed from baseline values at all time intervals during anesthesia (p<0.05). Heart rate decreased following the MED + MID injection (at T1, T2 and T3), and partially recovered by the reanimation period. Reflex response also differed between time 0 and all anesthesia time points (p<0.05). Mean amplitude of the P wave of the ECG was increased during MED + MID (T1) and KET (T2) anesthesia. The mean ST interval showed a large increase at T1, which was maintained throughout anesthesia (p <0.05). Albumin, glucose and the ALT enzyme decreased between T0 and T3. In conclusion, the use of MED+MID+KET and SEVO as an anesthetic combination altered cardiorespiratory and biochemical parameters of chickens, but no life-threatening effects were observed as a result of these changes. Hence, this drug combination can be adequately used as an anesthesia protocol in chickens.

Comparison of External Load Compensation During Rhythmic Arm Movements and Rhythmic Jaw Movements in Humans

1999 ◽  
Vol 82 (3) ◽  
pp. 1209-1217 ◽  
Author(s):  
J. H. Abbink ◽  
A. van der Bilt ◽  
F. Bosman ◽  
H. W. van der Glas ◽  
C. J. Erkelens ◽  
...  
Keyword(s):  
Biceps Brachii ◽  
Reflex Response ◽  
Reflex Activity ◽  
Digastric Muscle ◽  
Induced Responses ◽  
Rhythmic Movements ◽  
Jaw Muscles ◽  
Reflex Responses ◽  
Jaw Opening ◽  
Arm Muscles

Experiments were performed on human elbow flexor and extensor muscles and jaw-opening and -closing muscles to observe the effect on rhythmic movements of sudden loading. The load was provided by an electromagnetic device, which simulated the appearance of a smoothly increasing spring-like load. The responses to this loading were compared in jaw and elbow movements and between expected and unexpected disturbances. All muscles showed electromyographic responses to unexpected perturbations, with latencies of ∼65 ms in the arm muscles and 25 ms in the jaw. When loading was predictable, anticipatory responses started in arm muscles ∼200 ms before and in jaw muscles 100 ms before the onset of loading. The reflex responses relative to the anticipatory responses were smaller for the arm muscles than for the jaw muscles. The reflex responses in the arm muscles were the same with unexpected and expected perturbations, whereas anticipation increased the reflex responses in the jaw muscles. Biceps brachii and triceps brachii showed similar sensory-induced responses and similar anticipatory responses. Jaw muscles differed, however, in that the reflex response was stronger in masseter than in digastric. It was concluded that reflex responses in the arm muscles cannot overcome the loading of the arm adequately, which is compensated by a large centrally programmed response when loading is predictable. The jaw muscles, particularly the jaw-closing muscles, tend to respond mainly through reflex loops, even when loading of the jaw is anticipated. The differences between the responses of the arm and the jaw muscles may be related to physical differences. For example, the jaw was decelerated more strongly by the load than the heavier arm. The jaw was decelerated strongly but briefly, <30 ms during jaw closing, indicating that muscle force increased before the onset of reflex activity. Apparently, the force-velocity properties of the jaw muscles have a stabilizing effect on the jaw and have this effect before sensory induced responses occur. The symmetrical responses in biceps and triceps indicate similar motor control of both arm muscles. The differences in reflex activity between masseter and digastric muscle indicate fundamental differences in sensory feedback to the jaw-closing muscle and jaw-opening muscle.

No effect of prostaglandin synthesis inhibition on muscle reflexes in fetal lambs

1990 ◽  
Vol 258 (5) ◽  
pp. R1213-R1216
Author(s):  
D. Walker
Keyword(s):  
Mean Amplitude ◽  
Spinal Reflexes ◽  
Digastric Muscle ◽  
Neural Pathways ◽  
Semitendinosus Muscle ◽  
Fetal Breathing ◽  
Fetal Breathing Movements ◽  
Change In The Mean ◽  
The Mean ◽  
The Brain

The effects of inhibiting prostaglandin (PG) synthesis on fetal breathing movements and on the amplitude of reflex contraction of the digastric muscle (five trials) or hindlimb semitendinosus muscle (seven trials) has been studied in six fetal lambs at 123-139 days gestation. Infusion of either indomethacin (100 mg) or acetaminophen (300 mg) in 30 ml saline over 30 min resulted in an increase in the amplitude and incidence of breathing movements for 3-18 h in the different trials, but there was no change in the mean amplitude of either reflex or in the normal variation of reflex amplitude with changes in electrocortical activity. It is concluded that PGs modulate fetal breathing movements by an action on the brain stem chemoreceptors but do not alter the excitability of neural pathways subserving some cranial and spinal reflexes.

Excitatory and Inhibitory Purinergic Control of Neck Muscle Nociception in Anaesthetized Mice

Cephalalgia ◽  
2009 ◽  
Vol 29 (1) ◽  
pp. 58-67 ◽  
Author(s):  
M Reitz ◽  
A Makowska ◽  
J Ellrich
Keyword(s):  
Experimental Studies ◽  
Tension Type Headache ◽  
Neck Muscles ◽  
Neck Muscle ◽  
Dependent Manner ◽  
Jaw Opening ◽  
Jaw Opening Reflex ◽  
Subsequent Activation ◽  
Type Headache ◽  
The Impact

Tension-type headache is associated with noxious input from neck muscles. Due to the importance of purinergic mechanisms in muscle nociception, experimental studies typically inject α,β-methyleneadenosine 5′-triphosphate (α,β-meATP). In contrast to native adenosine 5′-triphosphate (ATP), α,β-meATP has a narrow receptor profile and remains stable in tissue. The present study administered α,β-meATP or ATP in semi-spinal neck muscles in anaesthetized mice (n = 65) in order to address different effects in neck muscle nociception. The jaw-opening reflex monitored the impact of neck muscle noxious input on brainstem processing. Injection of α,β-meATP induced reflex facilitation in a dose-dependent manner. In contrast, only the lowest ATP dosage evoked facilitation. Preceding P2Y1 receptor blockade revealed facilitation even under high-dosage ATP. Ongoing facilitation after α,β-meATP injection neutralized under subsequent activation of P2Y1 receptors. Results demonstrate opposing excitatory P2X and inhibitory P2Y effects of ATP in neck muscle nociception. These mechanisms may be involved in the pathophysiology of neck muscle pain in man.

Excitation and inhibition of neurons in the trigeminal nucleus caudalis following periaqueductal gray stimulation

1978 ◽  
Vol 56 (1) ◽  
pp. 157-161 ◽  
Author(s):  
R. K. Andersen ◽  
J. P. Lund ◽  
E. Puil
Keyword(s):  
Periaqueductal Gray ◽  
Infraorbital Nerve ◽  
Reflex Response ◽  
Tooth Pulp ◽  
Trigeminal Nucleus ◽  
Trigeminal Nucleus Caudalis ◽  
Jaw Opening ◽  
Narcotic Analgesia ◽  
Jaw Opening Reflex ◽  
Decerebrate Cats

Electrical stimulation (3–4 shocks, 300 Hz, 30–150 μA) of the periaqueductal gray matter (CG) or dorsal raphé nucleus (DR) of decerebrate cats reduced or abolished the jaw-opening reflex response evoked by stimulation of either the tooth pulp or infraorbital nerve. In addition, CG or DR stimulation inhibited the response of 12 out of 16 trigeminal nucleus caudalis neurons to activation of their sensory afferent inputs. Ten other neurons recorded in the same sites, and often at the same time, but which did not respond to the sensory inputs utilized, were excited by identical stimuli to CG or DR. This excitatory response was blocked by intravenously administered naloxone (0.1–0.2 mg/kg). It is suggested that those neurons which are excited by CG and DR stimulation may be interneurons involved in pre- and post-synaptic inhibition of sensory transmission during stimulus-produced or narcotic analgesia.

Effect of meal timing on diurnal rhythm of human cholesterol synthesis

1995 ◽  
Vol 269 (5) ◽  
pp. E878-E883 ◽  
Author(s):  
L. K. Cella ◽  
E. Van Cauter ◽  
D. A. Schoeller
Keyword(s):  
Diurnal Rhythm ◽  
Cholesterol Synthesis ◽  
Control Period ◽  
Mean Amplitude ◽  
Deuterium Incorporation ◽  
Strong Negative Correlation ◽  
Meal Timing ◽  
Fractional Synthetic Rate ◽  
The Mean ◽  
Male Subjects

To test whether the diurnal rhythm of cholesterol synthesis in humans is entrained to meal timing, the effect of a 6.5-h delay of mealtimes was investigated in four normal lipidemic male subjects. Cholesterol fractional synthetic rate was measured by deuterium incorporation from body water using blood sampling every 2 h. The baseline was a 24-h control period in which three Western-style meals were consumed at 0700, 1150, and 1640, followed by 3 days in which meals were delayed by 6.5 h, i.e., meals consumed at 1330, 1820, and 2310 without changing the sleep-wake and light-dark cycles. Cholesterol synthesis was maximal at 2200 +/- 0200 and minimal at 1130 +/- 0050 on the baseline day. On day 1 of the shifted meals, the maximum was delayed 6.0 +/- 0.5 h and the nadir was not changed. On day 3, the maximum was delayed 8.6 +/- 3.7 h and the minimum was delayed 6.5 +/- 2.4 h from baseline. The mean amplitude of the cholesterol rhythm was significantly greater on day 3,233 +/- 35%, compared with baseline which was 109 +/- 15%. A strong negative correlation (r = -0.66 +/- 0.10) was found between the rhythms of cholesterol synthesis and cortisol during the baseline day, but there was a phase delay in the rhythm of cholesterol synthesis relative to cortisol on day 1 and day 3. Findings indicate that the 24-h variation in cholesterol synthesis is strongly dependent on meal timing.

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