scholarly journals Role of the diaphragm in trunk rotation in humans

2011 ◽  
Vol 106 (4) ◽  
pp. 1622-1628 ◽  
Author(s):  
Anna L. Hudson ◽  
Jane E. Butler ◽  
Simon C. Gandevia ◽  
Andre De Troyer
Keyword(s):  
Significant Contribution ◽  
Motor Units ◽  
Emg Activity ◽  
Trunk Rotation ◽  
Single Motor Units ◽  
Inspiratory Activity ◽  
Monopolar Electrodes ◽  
The Right ◽  
Contralateral Rotation

The objectives of the present study were to test the hypothesis that the costal diaphragm contracts during ipsilateral rotation of the trunk and that such trunk rotation increases the motor output of the muscle during inspiration. Monopolar electrodes were inserted in the right costal hemidiaphragm in six subjects, and electromyographic (EMG) recordings were made during isometric rotation efforts of the trunk to the right (“ipsilateral rotation”) and to the left (“contralateral rotation”). EMG activity was simultaneously recorded from the parasternal intercostal muscles on the right side. The parasternal intercostals were consistently active during ipsilateral rotation but silent during contralateral rotation. In contrast, the diaphragm was silent in the majority of rotations in either direction, and whenever diaphragm activity was recorded, it involved very few motor units. In addition, whereas parasternal inspiratory activity substantially increased during ipsilateral rotation and decreased during contralateral rotation, inspiratory activity in the diaphragm was essentially unaltered and the discharge frequency of single motor units in the muscle remained at 13–14 Hz in the different postures. It is concluded that 1) the diaphragm makes no significant contribution to trunk rotation and 2) even though the diaphragm and parasternal intercostals contract in a coordinated manner during resting breathing, the inspiratory output of the two muscles is affected differently by voluntary drive during trunk rotation.

Interplay Between the Inspiratory and Postural Functions of the Human Parasternal Intercostal Muscles

2010 ◽  
Vol 103 (3) ◽  
pp. 1622-1629 ◽  
Author(s):  
Anna L. Hudson ◽  
Jane E. Butler ◽  
Simon C. Gandevia ◽  
Andre De Troyer
Keyword(s):  
Motor Units ◽  
Axial Rotation ◽  
Inspiratory Flow ◽  
Discharge Frequency ◽  
Dependent Manner ◽  
Intercostal Muscles ◽  
Inspiratory Muscles ◽  
Inspiratory Activity ◽  
The Right ◽  
Contralateral Rotation

The parasternal intercostal muscles are obligatory inspiratory muscles. To test the hypothesis that they are also involved in trunk rotation and to assess the effect of any postural role on inspiratory drive to the muscles, intramuscular electromyographic (EMG) recordings were made from the parasternal intercostals on the right side in six healthy subjects during resting breathing in a neutral posture (“neutral breaths”), during an isometric axial rotation effort of the trunk to the right (“ipsilateral rotation”) or left (“contralateral rotation”), and during resting breathing with the trunk rotated. The parasternal intercostals were commonly active during ipsilateral rotation but were consistently silent during contralateral rotation. In addition, with ipsilateral rotation, peak parasternal inspiratory activity was 201 ± 19% (mean ± SE) of the peak inspiratory activity in neutral breaths ( P < 0.001), and activity commenced earlier relative to the onset of inspiratory flow. These changes resulted from an increase in the discharge frequency of motor units (14.3 ± 0.3 vs. 11.0 ± 0.3 Hz; P < 0.001) and the recruitment of new motor units. The majority of units that discharged during ipsilateral rotation were also active in inspiration. However, with contralateral rotation, parasternal inspiratory activity was delayed relative to the onset of inspiratory flow, and peak activity was reduced to 72 ± 4% of that in neutral breaths ( P < 0.001). This decrease resulted from a decrease in the inspiratory discharge frequency of units (10.5 ± 0.2 vs. 12.0 ± 0.2 Hz; P < 0.001) and the derecruitment of units. These observations confirm that in addition to an inspiratory function, the parasternal intercostal muscles have a postural function. Furthermore the postural and inspiratory drives depolarize the same motoneurons, and the postural contraction of the muscles alters their output during inspiration in a direction-dependent manner.

Reflex responses in active muscles elicited by stimulation of low-threshold afferents from the human foot

1992 ◽  
Vol 67 (5) ◽  
pp. 1375-1384 ◽  
Author(s):  
A. M. Aniss ◽  
S. C. Gandevia ◽  
D. Burke
Keyword(s):  
Motor Units ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Onset Latency ◽  
Single Motor ◽  
Reflex Responses ◽  
Posterior Tibial ◽  
Single Motor Units ◽  
Low Threshold ◽  
Stimulation Of

1. Reflex responses were elicited in muscles that act at the ankle by electrical stimulation of low-threshold afferents from the foot in human subjects who were reclining supine. During steady voluntary contractions, stimulus trains (5 pulses at 300 Hz) were delivered at two intensities to the sural nerve (1.2-4.0 times sensory threshold) or to the posterior tibial nerve (1.1-3.0 times motor threshold for the intrinsic muscles of the foot). Electromyographic (EMG) recordings were made from tibialis anterior (TA), peroneus longus (PL), soleus (SOL), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles by the use of intramuscular wire electrodes. 2. As assessed by averages of rectified EMG, stimulation of the sural or posterior tibial nerves at nonpainful levels evoked a complex oscillation with onset latencies as early as 40 ms and lasting up to 200 ms in each muscle. The most common initial responses in TA were a decrease in EMG activity at an onset latency of 54 ms for sural stimuli, and an increase at an onset latency of 49 ms for posterior tibial stimuli. The response of PL to stimulation of the two nerves began with a strong facilitation of 44 ms (sural) and 49 ms (posterior tibial). With SOL, stimulation of both nerves produced early inhibition beginning at 45 and 50 ms, respectively. With both LG and MG, sural stimuli produced an early facilitation at 52-53 ms. However, posterior tibial stimuli produced different initial responses in these two muscles: facilitation in LG at 50 ms and inhibition in MG at 51 ms. 3. Perstimulus time histograms of the discharge of 61 single motor units revealed generally similar reflex responses as in multiunit EMG. However, different reflex components were not equally apparent in the responses of different single motor units: an individual motor unit could respond slightly differently with a change in stimulus intensity or background contraction level. The multiunit EMG record represents a global average that does not necessarily depict the precise pattern of all motor units contributing to the average. 4. When subjects stood erect without support and with eyes closed, reflex patterns were seen only in active muscles, and the patterns were similar to those in the reclining posture. 5. It is concluded that afferents from mechanoreceptors in the sole of the foot have multisynaptic reflex connections with the motoneuron pools innervating the muscles that act at the ankle. When the muscles are active in standing or walking, cutaneous feedback may play a role in modulating motoneuron output and thereby contribute to stabilization of stance and gait.

Role of central and peripheral chemoreceptors in diving responses of ducks

1982 ◽  
Vol 243 (5) ◽  
pp. R537-R545 ◽  
Author(s):  
D. R. Jones ◽  
W. K. Milsom ◽  
G. R. Gabbott
Keyword(s):  
Carotid Body ◽  
Significant Contribution ◽  
Cardiovascular Responses ◽  
Peripheral Circulation ◽  
Blood Gas ◽  
Peripheral Chemoreceptors ◽  
Central Chemoreceptors ◽  
The Right ◽  
Stimulation Of

Using techniques of vascular isolation and subsequent perfusion we have investigated the effects of altering blood gas tensions, in the cerebral and carotid body circulations, on some cardiovascular responses to diving in unanesthetized ducks. After denervating the right carotid body, perfusion of the innervated left carotid body with hyperoxic blood significantly reduced diving bradycardia and reduced the increase in hindlimb vascular resistance (HLVR) in 1-min dives compared with dives in which the innervated carotid body was autoperfused. Denervation of systemic arterial baroreceptors reduced the fall in heart rate (HR) and increased the rise in HLVR in all dives. Cross-perfusion of the head, from a donor with blood of normal blood gas tensions, did not significantly affect HR or HLVR in 2-min dives compared with dives in which the head was autoperfused. however, cross-perfusing the cerebral circulation with blood of elevated PaCO2 caused significantly greater increases in HLVR than when high PaCO2 only affected the peripheral circulation. We conclude that peripheral chemoreceptors cause virtually all the bradycardia in the later stages of a dive but only about one-half the increase in HLVR, a significant contribution comes from the stimulation of central chemoreceptors with blood of high PaCO2.

Specificity of esophageal electrode recordings of posterior cricoarytenoid muscle activity

1989 ◽  
Vol 66 (3) ◽  
pp. 1501-1505 ◽  
Author(s):  
G. Insalaco ◽  
G. Sant'Ambrogio ◽  
F. B. Sant'Ambrogio ◽  
S. T. Kuna ◽  
O. P. Mathew
Keyword(s):  
Marked Decrease ◽  
Upper Airway ◽  
Emg Activity ◽  
Small Reduction ◽  
Posterior Cricoarytenoid Muscle ◽  
Intramuscular Electrodes ◽  
Inspiratory Activity ◽  
Recorded Activity ◽  
Posterior Cricoarytenoid ◽  
The Right

Esophageal electrodes have been used for recording the electromyographic (EMG) activity of the posterior cricoarytenoid muscle (PCA). To determine the specificity of this EMG technique, esophageal electrode recordings were compared with intramuscular recordings in eight anesthetized mongrel dogs. Intramuscular wire electrodes were placed in the right and left PCA, and the esophageal electrode was introduced through the nose or mouth and advanced into the upper esophagus. On direct visualization of the upper airway, the unshielded catheter electrode entered the esophagus on the right or left side. Cold block of the recurrent laryngeal nerve (RLN) ipsilateral to the esophageal electrode was associated with a marked decrease in recorded activity, whereas cold block of the contralateral RLN resulted only in a small reduction in activity. After supplemental doses of anesthesia were administered, bilateral RLN cold block essentially abolished the activity recorded with the intramuscular electrodes as well as that recorded with the esophageal electrode. Before supplemental doses of anesthesia were given, especially after vagotomy, the esophageal electrode, and in some cases the intramuscular electrodes, recorded phasic inspiratory activity not originating from the PCA. Therefore, one should be cautious in interpreting the activity recorded from esophageal electrodes as originating from the PCA, especially in conditions associated with increased respiratory efforts.

Functional Activity of Superior Head of Human Lateral Pterygoid Muscle during Isometric Force

2005 ◽  
Vol 84 (6) ◽  
pp. 548-553 ◽  
Author(s):  
S. Ruangsri ◽  
T. Whittle ◽  
K. Wanigaratne ◽  
G.M. Murray
Keyword(s):  
Computer Tomography ◽  
Functional Activity ◽  
Isometric Force ◽  
Motor Units ◽  
Emg Activity ◽  
Single Muscle ◽  
Lateral Pterygoid Muscle ◽  
Functional Activities ◽  
Single Motor ◽  
Single Motor Units

There is controversy as to the jaw tasks for which the superior head of the human lateral pterygoid muscle (SHLP) becomes active. The aim was to describe the functional activities of SHLP single motor units (SMUs) during horizontal isometric force tasks. In 11 subjects, 48 SMUs were recorded from computer-tomography-verified SHLP sites during generation of horizontal isometric force in the contralateral (CL), protrusive (P), and ipsilateral (IL) directions and intermediate directions (CL-P, IL-P). In eight subjects, SHLP SMUs were active in CL, CL-P, and P. Qualitatively, SHLP EMG activity increased with increased isometric force. Forty-two SMUs were active in directions other than IL; 6 exhibited activity at IL and other directions. The similarity of these data to previous human lateral pterygoid (IHLP) data supports the notion that SHLP and IHLP should be regarded as a single muscle, with activities shaded according to the biomechanical demands of the task.

scholarly journals Periodic Modulation of Motor-Unit Activity in Extrinsic Hand Muscles During Multidigit Grasping

2005 ◽  
Vol 94 (1) ◽  
pp. 206-218 ◽  
Author(s):  
Jamie A. Johnston ◽  
Sara A. Winges ◽  
Marco Santello
Keyword(s):  
Motor Unit ◽  
Motor Units ◽  
Flexor Digitorum Profundus ◽  
Common Input ◽  
Hand Muscles ◽  
Single Motor Units ◽  
Flexor Digitorum ◽  
The Relationship ◽  
Muscle Coherence

We recently examined the extent to which motor units of digit flexor muscles receive common input during multidigit grasping. This task elicited moderate to strong motor-unit synchrony (common input strength, CIS) across muscles (flexor digitorum profundus, FDP, and flexor pollicis longus, FPL) and across FDP muscle compartments, although the strength of this common input was not uniform across digit pairs. To further characterize the neural mechanisms underlying the control of multidigit grasping, we analyzed the relationship between firing of single motor units from these hand muscles in the frequency domain by computing coherence. We report three primary findings. First, in contrast to what has been reported in intrinsic hand muscles, motor units belonging to different muscles and muscle compartments of extrinsic digit flexors exhibited significant coherence in the 0- to 5- and 5- to 10-Hz frequency ranges and much weaker coherence in the higher 10–20 Hz range (maximum 0.0025 and 0.0008, respectively, pooled across all FDP compartment pairs). Second, the strength and incidence of coherence differed considerably across digit pairs. Third, contrary to what has been reported in the literature, across-muscle coherence can be stronger and more prevalent than within-muscle coherence, as FPL–FDP2 (thumb-index digit pair) exhibited the strongest and most prevalent coherence in our data (0.010 and 43% at 3 Hz, respectively). The heterogeneous organization of common input to these muscles and muscle compartments is discussed in relation to the functional role of individual digit pairs in the coordination of multiple digit forces in grasping.

scholarly journals Role of Auriculotherapy in the Treatment of Temporomandibular Disorders with Anxiety in University Students

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Denise Hollanda Iunes ◽  
Érika de Cássia Lopes Chaves ◽  
Caroline de Castro Moura ◽  
Bruna Côrrea ◽  
Leonardo César Carvalho ◽  
...  
Keyword(s):  
University Students ◽  
Temporomandibular Disorders ◽  
Sham Group ◽  
Treatment Protocol ◽  
Emg Activity ◽  
Submandibular Region ◽  
Temporal Muscle ◽  
The Right ◽  
Mustard Seeds

Introduction. The aim of this study was to evaluate the role of auriculotherapy with mustard seeds in the treatment of temporomandibular disorders (TMDs), anxiety, and electromyographic (EMG) activity in university students.Methodology. The State Trait Anxiety Inventory (STAI), Research Diagnostic Criteria (RDC) for TMDs (RDC/TMDs), and electromyography were used in this study of 44 college students with high levels of anxiety and TMDs. The subjects were divided into two groups: an auriculotherapy (AA) group(n=31)and an AA sham group(n=13). The mustard seeds were applied to the shenmen, rim, sympathetic, brain stem, and temporomandibular joint (TMJ) points in the AA group and to sham points in the external ear and wrist in the AA sham group. The treatment protocol was 10 sessions (two treatments per week).Results. Anxiety(p<0.01)was significantly reduced in the AA group. This group also showed a decrease in tender points in the mandibular posterior region(p=0.04)and in the right side of the submandibular region(p=0.02). Complaints of bilateral pain were reduced in the temporal tendon(p≤0.01)and in the left side of the ATM(p<0.01). In addition, electromyographic (EMG) activity was reduced during temporal muscle contraction(p=0.03).  Conclusion. Auriculotherapy was effective in the treatment of students with anxiety and TMDs.

scholarly journals Reflex Inhibition in Human Biceps Brachii Decreases With Practice of a Fatiguing Contraction

2008 ◽  
Vol 100 (5) ◽  
pp. 2843-2851 ◽  
Author(s):  
Zachary A. Riley ◽  
Stéphane Baudry ◽  
Roger M. Enoka
Keyword(s):  
Motor Neurons ◽  
Radial Nerve ◽  
Biceps Brachii ◽  
Motor Units ◽  
Elbow Flexion ◽  
Emg Activity ◽  
Time To Failure ◽  
Reflex Inhibition ◽  
Single Motor Units ◽  
Rate Of Increase

The purpose of the study was to examine the influence of practice on time to failure of a submaximal contraction with the elbow flexor muscles and on reflex inhibition from brachioradialis afferents onto biceps brachii motor neurons. Fifteen subjects practiced sustaining an isometric contraction (20% of maximum) with the elbow flexors until failure. Spike-triggered stimulation was used to assess the influence of radial nerve stimulation on the discharge of single motor units in biceps brachii before and after three practice sessions. Time to failure increased from 760 ± 333 s in session 1 to 1,103 ± 415 s in session 3 ( P < 0.03) and was accompanied by a slower rate of increase in electromyographic (EMG) activity of the short head of biceps brachii ( P < 0.05). Stimulation of the radial nerve prolonged the interspike interval before practice ( n = 56; 7.2 ± 6.8 ms; P < 0.001), and this effect was reduced after practice ( n = 62; 2.3 ± 3.6 ms; P < 0.01). The reduction was greater for motor units in the short head of biceps brachii than for those in the long head ( P < 0.05) and was associated with a slower rate of increase in EMG ( r = 0.57, P = 0.03). The decrease in reflex inhibition was the main predictor of the increase in time to failure ( r2 = 0.60, P = 0.001). These results demonstrate that practice reduced an antagonistic inhibition and improved the ability of the muscles to perform a synergistic action of elbow flexion.

Discharge properties of primate forearm motor units during isometric muscle activity

1985 ◽  
Vol 54 (5) ◽  
pp. 1178-1193 ◽  
Author(s):  
S. S. Palmer ◽  
E. E. Fetz
Keyword(s):  
Firing Rate ◽  
Microelectrode Array ◽  
Rhesus Macaques ◽  
Motor Units ◽  
Emg Activity ◽  
Hold Period ◽  
Single Motor Units ◽  
Extensor Muscles ◽  
Discharge Patterns ◽  
Static Torque

Activity of single motor units (MUs) was recorded in forelimb muscles of rhesus macaques while they generated isometric ramp-and-hold torques about the wrist. Multiunit electromyographic (EMG) activity was recorded from 10-12 identified flexor and extensor muscles of the wrist and digits with implanted EMG wire electrodes. Single MUs from these muscles were recorded with a remotely controlled tripolar microelectrode array. The parent muscle of each MU was determined by compiling MU-triggered averages of multiunit EMGs. The MU firing patterns during the isometric task were determined from response histograms aligned with change in torque. At moderate torque levels, MUs (n = 86) exhibited four types of discharge patterns during the ramp-and-hold trajectory: phasic-tonic (23%), tonic (33%), decrementing (39%), and phasic (5%). Phasic-tonic MUs exhibited a phasic burst of activity during the torque ramp which exceeded the firing rate during the static hold period. Both phasic-tonic and tonic MUs exhibited a constant mean firing rate during the hold period; the discharge of decrementing MUs gradually decreased during the static hold. Phasic MUs fired only during the change in force. The relation between MU firing rate and torque was investigated as the monkeys generated responses of different levels of static torque during the hold period. Mean firing rate during the hold was found to be proportional to static torque up to moderate torque levels, where it reached a maximum. In the linear range, the mean rate-torque slope was 3.4 +/- 1.9 imp/s per 10(5) dyn . cm (n = 9).

scholarly journals Motor Responses of Lumbar Erector Spinae Induced by Electrical Vestibular Stimulation in Seated Participants

2021 ◽  
Vol 15 ◽  
Author(s):  
Amélie Desgagnés ◽  
Mikaël Desmons ◽  
Jean-Philippe Cyr ◽  
Martin Simoneau ◽  
Hugo Massé-Alarie
Keyword(s):  
Head Rotation ◽  
Vestibular Stimulation ◽  
Erector Spinae ◽  
Body Sway ◽  
Emg Activity ◽  
Motor Responses ◽  
Eyes Open ◽  
Latency Response ◽  
The Right

Introduction: The study of motor responses induced by electrical vestibular stimulation (EVS) may help clarify the role of the vestibular system in postural control. Although back muscles have an important role in postural control, their EVS-induced motor responses were rarely studied. Moreover, the effects of EVS parameters, head position, and vision on EVS-induced back muscles responses remain little explored.Objectives: To explore the effects of EVS parameters, head position, and vision on lumbar erector spinae muscles EVS-induced responses.Design: Exploratory, cross-sectional study.Materials and Methods: Ten healthy participants were recruited. Three head positions (right, left and no head rotation), 4 intensities (2, 3, 4, 5 mA), and 4 EVS durations (5, 20, 100, 200 ms) were tested in sitting position with eyes open or closed. EVS usually induced a body sway toward the anode (placed on the right mastoid). EMG activity of the right lumbar erector spinae was recorded. Variables of interest were amplitude, occurrence, and latency of the EVS-induced modulation of the EMG activity.Results: The short-latency response was inhibitory and the medium-latency response was excitatory. Increased EVS current intensity augmented the occurrence and the amplitude of the short- and medium-latency responses (more inhibition and more excitation, respectively). EVS duration influenced the medium-latency response differently depending on the position of the head. Right head rotation produced larger responses amplitude and occurrence than left head rotation. Opposite head rotation (left vs. right) did not induce a reversal of the short- and medium-latency responses (i.e., the inhibition did not become an excitation), as typically reported in lower legs muscles. The eyes open condition did not modulate muscle responses.Conclusion: Modulation of EVS parameters (current intensity and duration of EVS) affects the amplitude and occurrence of the lumbar erector spinae responses. In contrast, vision did not influence the responses, suggesting its minimal contribution to vestibulomotor control in sitting. The lack of response reversal in sagittal plane may reflect the biomechanical role of lumbar erector spinae to fine-tune the lumbar lordosis during the induced body sway. This hypothesis remains to be further tested.

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