Electrical Activity from the Superior Pharyngeal Constrictor During Reflexive and Nonreflexive Tasks

1989 ◽  
Vol 32 (4) ◽  
pp. 749-754 ◽  
Author(s):  
Adrienne L. Perlman ◽  
Erich S. Luschei ◽  
Charles E. Du Mond
Keyword(s):  
Electrical Activity ◽  
Healthy Subjects ◽  
General Trend ◽  
Human Subjects ◽  
Electrode Placement ◽  
Emg Activity ◽  
Constrictor Muscle ◽  
Natural Logarithm ◽  
Quantitative Manner ◽  
Normal Human

The purpose of this investigation was to determine, in a quantitative manner, which, if any, nonswallowing tasks produce significant levels of activation in the superior pharyngeal constrictor muscle of normal human subjects. Bipolar hooked wire electrodes were inserted in the superior pharyngeal constrictor muscle of 15 healthy subjects. Electrode placement was controlled. Each subject performed two reflexive tasks, six voluntary tasks requiring phonation, and four nonspeech voluntary tasks. The electromyogram (EMG) was rectified and integrated. The resulting number was then transformed by taking its natural logarithm. An ANOVA was performed and a linear model was estimated. The magnitude of the EMG activity was related to the location of the electrodes. The largest values were recorded in the lateral-superior placement, followed by the lateral-inferior, medial-inferior and medial-superior. The superior pharyngeal contrictor was found to be a muscle activated primarily during reflexive activity. There was a general trend in the amplitude of EMG activity in relationship to task. Swallowing produced the greatest amount of activity and a gag produced about 60% of the activity produced by the swallow. Two tasks, production of the work /hk/ in which the phoneme /k/ was stressed, and a "modified Valsalva," which was actually a hard /k/ held for several seconds, produced the next greatest level of EMG.

scholarly journals Control Strategies for the Transition From Multijoint to Single-Joint Arm Movements Studied Using a Simple Mechanical Constraint

2000 ◽  
Vol 83 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Robert A. Scheidt ◽  
W. Zev Rymer
Keyword(s):  
Control Strategies ◽  
Human Subjects ◽  
Dynamic Performance ◽  
Activity Patterns ◽  
Adaptive Controller ◽  
Emg Activity ◽  
Joint Control ◽  
Primary Role ◽  
Joint Task ◽  
Normal Human

Changes were studied in neuromotor control that were evoked by constraining the motion of the elbow joint during planar, supported movements of the dominant arm in eight normal human subjects. Electromyograph (EMG) recordings from shoulder and arm muscles were used to determine whether the normal multijoint muscle activity patterns associated with reaching to a visual target were modified when the movement was reduced to a single-joint task, by pinning the elbow to a particular location in the planar work space. Three blocks of 150 movements each were used in the experiments. Subjects were presented with the unconstrained task in the first and third blocks with an intervening block of constrained trials. Kinematic, dynamic, and EMG measures of performance were compared across blocks. The imposition of the pin constraint caused predictable changes in kinematic performance, in that near-linear motions of the hand became curved. This was followed by changes in limb dynamic performance at the elbow. However, changes in EMG activity at the shoulder lagged the kinematic changes substantially (by about 15 trials). The gradual character of the changes in EMG timing does not support a primary role for segmental reflex action in mediating the transition between multijoint and single-joint control strategies. Furthermore, the scope and magnitude of these changes argues against the notion that human motor performance is driven by the optimization of muscle- or joint-related criteria alone. The findings are best described as reflecting the actions of a feedforward adaptive controller that has properties that are modified progressively according to the environmental state.

The electromyographic response to sudden stretches of limb muscles in normal human subjects

1978 ◽  
Vol 56 (5) ◽  
pp. 771-776 ◽  
Author(s):  
M. D. O'Riain ◽  
R. D. G. Blair ◽  
J. T. Murphy
Keyword(s):  
Human Subjects ◽  
Spinal Reflex ◽  
Emg Activity ◽  
Muscle Stretch ◽  
Wrist Flexor ◽  
Extensor Muscles ◽  
Limb Muscles ◽  
Normal Human ◽  
The Individual

The electromyographic (EMG) activity following a sudden stretch applied to wrist flexor or extensor muscles was investigated using a method which enabled the individual records and cumulative results of 30 trials to be observed simultaneously. The results showed that in each case the spinal reflex EMG burst was followed by one or two additional reflex bursts. The second of these latter bursts, when present, occurred in one of two distinct latency ranges. Thus, three distinct latency ranges were observed for reflex bursts following the spinal reflex burst. A possible explanation for these results is that there are three distinct long-loop reflexes, one or two of which may be active following a muscle stretch. The present results do not distinguish whether any or all of these long-loop reflexes are segmental or supraspinal in origin.

scholarly journals ECG Electrode Placements for Magnetohydrodynamic Voltage Suppression

2018 ◽  
Vol 4 (7) ◽  
pp. 94
Author(s):  
T. Gregory ◽  
John Oshinski ◽  
Zion Tse
Keyword(s):  
Healthy Subjects ◽  
Human Subjects ◽  
Vector Model ◽  
Electrode Placement ◽  
Qrs Complex ◽  
Ecg Signals ◽  
Qrs Complex Detection ◽  
Group 2 ◽  
Magnetic Resonance Imaging Mri ◽  
Group 1

This study aims to investigate a set of electrocardiogram (ECG) electrode lead locations to improve the quality of four-lead ECG signals acquired during magnetic resonance imaging (MRI). This was achieved by identifying electrode placements that minimized the amount of induced magnetohydrodynamic voltages (VMHD) in the ECG signals. Reducing VMHD can improve the accuracy of QRS complex detection in ECG as well as heartbeat synchronization between MRI and ECG during the acquisition of cardiac cine. A vector model based on thoracic geometry was developed to predict induced VMHD and to optimize four-lead ECG electrode placement for the purposes of improved MRI gating. Four human subjects were recruited for vector model establishment (Group 1), and five human subjects were recruited for validation of VMHD reduction in the proposed four-lead ECG (Group 2). The vector model was established using 12-lead ECG data recorded from Group 1 of four healthy subjects at 3 Tesla, and a gradient descent optimization routine was utilized to predict optimal four-lead ECG placement based on VMHD vector alignment. The optimized four-lead ECG was then validated in Group 2 of five healthy subjects by comparing the standard and proposed lead placements. A 43.41% reduction in VMHD was observed in ECGs using the proposed electrode placement, and the QRS complex was preserved. A VMHD-minimized electrode placement for four-lead ECG gating was presented and shown to reduce induced magnetohydrodynamic (MHD) signals, potentially allowing for improved cardiac MRI physiological monitoring.

Sumatriptan Does Not Affect Arteriovenous Oxygen Differences in Jugular and Cubital Veins in Normal Human Subjects

Cephalalgia ◽  
2008 ◽  
Vol 28 (10) ◽  
pp. 1081-1085 ◽  
Author(s):  
T Wienecke ◽  
JM Hansen ◽  
J Petersen ◽  
KS Olsen ◽  
M Ashina ◽  
...  
Keyword(s):  
Blood Flow ◽  
Nervous System ◽  
Healthy Subjects ◽  
Jugular Vein ◽  
Human Subjects ◽  
External Jugular Vein ◽  
Arteriovenous Anastomoses ◽  
Subcutaneous Sumatriptan ◽  
Normal Human ◽  
Sympathetic Nervous

Arteriovenous anastomoses (AVAs) may open up during migraine attacks. In studies with anaesthetized and bilaterally vagosympatectomized pigs, triptans reduce AVA blood flow and increase the arteriovenous O2 difference (AVDO2). To investigate whether subcutaneous sumatriptan 6 mg could induce changes in the AVDO2, we measured the AVDO2 in the external jugular vein in healthy subjects. We also measured the AVDO2 in the internal jugular and cubital veins. There were no changes in AVDO2 after subcutaneous sumatriptan, probably because AVA blood flow is limited in humans with an intact sympathetic nervous system.

scholarly journals Dependence of EMG Responses Evoked by Imposed Wrist Displacements on Pre-existing Activity in the Stretched Muscles

1984 ◽  
Vol 11 (2) ◽  
pp. 272-280 ◽  
Author(s):  
W. Bedingham ◽  
W.G. Tatton
Keyword(s):  
Background Activity ◽  
Human Subjects ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Onset Latency ◽  
Normal Human ◽  
Motoneuron Activity ◽  
Movement Parameters ◽  
The Relationship

ABSTRACT:The relationship between the segmented EMG activity in flexor carpi radialis evoked by imposed angular wrist displacement was studied with respect to the level of pre-existing background activity in 30 normal human subjects. Input-output response planes demonstrate that the magnitude of the Ml & M2-3 segments is dependent on both the displacement parameters and the level of pre-existing EMG activity in the stretched muscle. If the level of background activity exceeded 4-5% of the maximum voluntary contraction, the onset latency of the M1 segment and duration of the Ml and the M2-3 segments remained constant (within ± 2 msec) for different magnitudes of step load displacements, despite marked variation in the range of the displacement’s amplitude, duration, velocity, and acceleration. We propose that the dependency of the relationship between reflex magnitude and imposed movement parameters on tonic motoneuron activity, as represented by pre-existing EMG levels, may reflect an automatic adjustment mechanism that could be utilized in servo compensation of movements requiring markedly different force levels.

Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

2005 ◽  
Vol 289 (1) ◽  
pp. R148-R155 ◽  
Author(s):  
J. J. Rutherford ◽  
T. H. Clutton-Brock ◽  
M. J. Parkes
Keyword(s):  
Healthy Subjects ◽  
Wave Amplitude ◽  
Human Subjects ◽  
Coronary Artery Spasm ◽  
Normal Subjects ◽  
T Wave ◽  
Diagnostic Potential ◽  
Normal Human ◽  
Electrocardiogram Ecg ◽  
Mean Heart Rate

During voluntary hyperventilation in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O2) supply and availability to the heart. This can induce local epicardial coronary artery spasm in susceptible patients. Its diagnostic potential for detection of early heart disease is unclear. This is because such hypocapnia produces an inconsistent and irreproducible effect on electrocardiogram (ECG) in healthy subjects. To resolve this inconsistency, we have applied two new experimental techniques in normal, healthy subjects to measure the effects of hypocapnia on their ECG: mechanical hyperventilation and averaging of multiple ECG cycles. In 15 normal subjects, we show that hypocapnia (20 ± 1 mmHg) significantly reduced mean T wave amplitude by 0.1 ± 0.0 mV. Hypocapnia also increased mean heart rate by 4 beats/min without significantly altering blood pressure, ionized calcium or potassium levels, or the R wave or other features of the ECG. We therefore provide the first unequivocal demonstration that hypocapnia does consistently reduce T wave amplitude in normal, healthy subjects.

Afferent contributions to stretch-evoked myoelectric responses

1982 ◽  
Vol 48 (2) ◽  
pp. 403-418 ◽  
Author(s):  
R. J. Jaeger ◽  
G. L. Gottlieb ◽  
G. C. Agarwal ◽  
A. J. Tahmoush
Keyword(s):  
Ulnar Nerve ◽  
Elbow Joint ◽  
Human Subjects ◽  
Initial Position ◽  
Emg Activity ◽  
Muscle Vibration ◽  
Sensory Impairment ◽  
Flexor Carpi Ulnaris ◽  
Normal Human ◽  
Extensor Carpi Radialis

1. Step torque perturbations were applied to flex or extend the wrists of normal human subjects who were instructed to restore the joint to its initial position as quickly as possible. The resulting electromyographic (EMG) activity was recorded from the flexor carpi radialis, flexor carpi ulnaris, and extensor carpi radialis. Experiments were performed under control and three altered conditions of the limb: 1) ischemia, 2) vibration, and 3) local ulnar nerve anesthesia. The effects of the procedures on the EMG responses in four poststimulus intervals--the myotatic (30-60 ms), late myotatic (60-120 ms), postmyotatic (120-200 ms), and stabilizing (200-400 ms)--were studied. 2. Ischemia was induced in the forearm by means of a sphygmomanometer cuff inflated to 150 mm of mercury around the upper arm. After about 20 min of ischemia the stretch-evoked EMG activity over the 30-60-ms and 60-120-ms intervals were abolished, while the longer latency responses persisted. 3. Vibration at frequencies between 50 and 120 Hz was applied to the tendon of the stretched muscle. Vibration consistently reduced the EMG activity only in the 30-60-ms interval. 4. The ulnar nerve was blocked near the elbow joint by local anesthetic. Varying degrees of block were obtained, from a mild sensory impairment to a complete block. At intermediate degrees of block, EMG activity in the 30-60-ms and 60-120-ms intervals were attenuated with little alteration in later responses. 5. The data are used to differentiate functionally the myoelectric responses evoked in four poststimulus time segments in the stretched muscle by step torque perturbations.

Incomplete Functional Subdivision of the Human Multitendoned Finger Muscle Flexor Digitorum Profundus: An Electromyographic Study

2003 ◽  
Vol 90 (4) ◽  
pp. 2560-2570 ◽  
Author(s):  
Karen T. Reilly ◽  
Marc H. Schieber
Keyword(s):  
Functional Organization ◽  
Human Subjects ◽  
Motor Units ◽  
Flexor Digitorum Profundus ◽  
Emg Activity ◽  
Finger Movements ◽  
Left Hand ◽  
Normal Human ◽  
Neuromuscular Compartments ◽  
Flexor Digitorum

The human flexor digitorum profundus (FDP) sends tendons to all 4 fingers. One might assume that this multitendoned muscle consists of 4 discrete neuromuscular compartments each acting on a different finger, but recent anatomical and physiological studies raise the possibility that the human FDP is incompletely subdivided. To investigate the functional organization of the human FDP, we recorded electromyographic (EMG) activity by bipolar fine-wire electrodes simultaneously from 2 or 4 separate intramuscular sites as normal human subjects performed isometric, individuated flexion, and extension of each left-hand digit. Some recordings showed EMG activity during flexion of only one of the 4 fingers, indicating that the human FDP has highly selective core regions that act on single fingers. The majority of recordings, however, showed a large amount of EMG activity during flexion of one finger and lower levels of EMG activity during flexion of an adjacent finger. This lesser EMG activity during flexion of adjacent fingers was unlikely to have resulted from recording motor units in neighboring neuromuscular compartments, and instead suggests incomplete functional subdivision of the human FDP. In addition to the greatest agonist EMG activity during flexion of a given finger, most recordings also showed EMG activity during extension of adjacent fingers, apparently serving to stabilize the given finger against unwanted extension. Paradoxically, the functional organization of the human FDP—with both incomplete functional subdivision and highly selective core regions—may contribute simultaneously to the inability of humans to produce completely independent finger movements, and to the greater ability of humans (compared with macaques) to individuate finger movements.

Observations on a Relationship between Steroid Metabolism and the Concentration of Plasma Fibrinogen

1963 ◽  
Vol 10 (02) ◽  
pp. 400-405 ◽  
Author(s):  
B. A Amundson ◽  
L. O Pilgeram
Keyword(s):  
Blood Coagulation ◽  
Methyl Ether ◽  
Broad Spectrum ◽  
Human Subjects ◽  
Plasma Fibrinogen ◽  
Steroid Metabolism ◽  
Specific Site ◽  
Chain Reaction ◽  
Normal Human ◽  
A Chain

SummaryEnovid (5 mg norethynodrel and 0.075 mg ethynylestradiol-3-methyl ether) therapy in young normal human subjects causes an increase in plasma fibrinogen of 32.4% (P >C 0.001). Consideration of this effect together with other effects of Enovid on the activity of specific blood coagulatory factors suggests that the steroids are exerting their effect at a specific site of the blood coagulation and/or fibrinolytic system. The broad spectrum of changes which are induced by the steroids may be attributed to a combination of a chain reaction and feed-back control.

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