Characteristic Alterations in Responses to Imposed Wrist Displacements in Parkinsonian Rigidity and Dystonia Musculorum Deformans

ABSTRACT:The amplitude and temporal modulation of the segmented EMG activity in flexor carpi radialis, evoked by imposed angular wrist extension, was studied with respect to the level of pre-existing background activity in rigid parkinsonian (PK) and dystonia musculorum deformans (DMD) patients. The interdependence of the evoked M1 and M2-3 segments on pre-existing background EMG activity and initial velocity of imposed displacement was established previously for a normal population. Individual responses of 21 parkinsonian and 12 dystonic patients were compared to the established normal “response volume”. The augmented magnitude of the M2-3 segment in rigid PK patients, which correlates to the measure of rigidity, could not be accounted for by the low level of pre-existing EMG activity. Therefore, increased descending facilitation does not impinge directly on alpha motoneurons. Paradoxical excitation in the shortened muscle and resetting of tonic tremor of the stretched muscle by the imposed wrist extension are two other demonstrated abnormalities which may also contribute to PK rigidity. In contrast, DMD patients demonstrated normal amplitude modulation of the M1 and M2-3 segments, but exhibited a disturbance of normal temporal mechanisms that result in constant duration of the M1 and M2-3 responses with imposed force step loads.

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The effect of a cadence retraining protocol on lower limb sagittal plane kinematics and EMG activity in a normal population of social runners

Journal of Science and Medicine in Sport ◽

10.1016/j.jsams.2016.12.062 ◽

2017 ◽

Vol 20 ◽

pp. e26

Author(s):

C. Maher ◽

P. Tinley ◽

L. Donnan

Keyword(s):

Lower Limb ◽

Sagittal Plane ◽

Normal Population ◽

Emg Activity

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Evidence that a disordered servo-like mechanism contributes to tremor in movements during cerebellar dysfunction

Journal of Neurophysiology ◽

10.1152/jn.1986.56.1.123 ◽

1986 ◽

Vol 56 (1) ◽

pp. 123-136 ◽

Cited By ~ 44

Author(s):

J. Hore ◽

D. Flament

Keyword(s):

Visual Feedback ◽

Initial Velocity ◽

Cerebellar Nuclei ◽

Emg Activity ◽

Constant Force ◽

Inverse Relation ◽

Cerebellar Dysfunction ◽

Antagonist Activity ◽

Initial Decrease ◽

Cebus Monkeys

The characteristics of discontinuities and tremor that occurred in elbow flexions during cooling of the lateral cerebellar nuclei were investigated in five Cebus monkeys. Discontinuities in movements appeared as rhythmical oscillations (kinetic tremor) when movements were slow or when movements were made with a constant force that loaded the antagonist. These oscillations had similar properties to cerebellar terminal tremor following movements; e.g., their amplitude and frequency were decreased by addition of mass to the handle and they occurred in the absence of visual feedback. The abnormal initial decrease in velocity that initiated oscillations in flexion movements was associated with abnormally early or large antagonist (triceps) electromyogram (EMG) activity. This abnormal EMG activity did not follow the normal inverse relation between initial velocity and antagonist latency from onset of movement. The initial deflection from the expected trajectory was opposed by a second burst of EMG activity in the agonist (biceps). This second burst was not the continuation of a step of EMG activity because its amplitude was often larger than the amplitude of the first agonist burst. The second agonist burst had the properties of a servo-like response: it occurred when biceps shortening was slowed (but biceps was not stretched), its magnitude was proportional to the magnitude or the deflection in velocity, its latency was 50-80 ms from onset of the abnormal decrease in velocity, and it occurred in the absence of visual feedback. However, this servo-like response was disordered because it did not return the limb accurately to the expected trajectory. The servo-like mechanism was studied further by applying torque pulse perturbations during elbow flexions. When the cerebellar nuclei were cooled, agonist responses to the perturbation were proportional to the size of the velocity deflection, but they were prolonged and onset of antagonist activity was delayed. It is suggested that discontinuities and tremor in movements during cerebellar dysfunction result from the same mechanism: alternation between disordered stretch reflexes and disordered servo-assistance mechanisms, both partly involving transcortical pathways.

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

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100045534 ◽

1984 ◽

Vol 11 (2) ◽

pp. 272-280 ◽

Cited By ~ 63

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.

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Effect of Computer Keyboard Slope on Wrist Position and Forearm Electromyography of Typists Without Musculoskeletal Disorders

Physical Therapy ◽

10.1093/ptj/83.9.816 ◽

2003 ◽

Vol 83 (9) ◽

pp. 816-830 ◽

Cited By ~ 47

Author(s):

Guy G Simoneau ◽

Richard W Marklin ◽

Joseph E Berman

Keyword(s):

Carpal Tunnel ◽

Physical Therapists ◽

Maximum Voluntary Contraction ◽

Slope Angle ◽

Voluntary Contraction ◽

Emg Activity ◽

Electromyographic Activity ◽

Wrist Extension ◽

Computer Keyboard ◽

Downward Slope

Background and Purpose. Positioning a computer keyboard with a downward slope reduces wrist extension needed to use the keyboard and has been shown to decrease pressure in the carpal tunnel. However, whether a downward slope of the keyboard reduces electromyographic (EMG) activity of the forearm muscles, in particular the wrist extensors, is not known. Subjects and Methods. Sixteen experienced typists participated in this study and typed on a conventional keyboard that was placed on slopes at angles of 7.5, 0, −7.5, and −15 degrees. Electromyographic activity of the extensor carpi ulnaris (ECU), flexor carpi ulnaris (FCU), and flexor carpi radialis (FCR) muscles was measured with surface electrodes, while the extension and ulnar deviation angles of the right and left wrists were measured with electrogoniometers. Results. Wrist extension angle decreased from approximately 12 degrees of extension while typing on a keyboard with a 7.5-degree slope to 3 degrees of flexion with the keyboard at a slope of −15 degrees. Although the differences were in the range of 1% to 3% of maximum voluntary contraction (MVC), amplitude probability distribution function (APDF) of root-mean-square EMG data points from the ECU, FCU, and FCR muscles varied across keyboard slopes. Discussion and Conclusion. Wrist extension decreased as the keyboard slope decreased. Furthermore, a slight decrease in percentage of MVC of the ECU muscle was noted as the keyboard slope decreased. Based on biomechanical modeling and published work on carpal tunnel pressure, both of these findings appear to be positive with respect to comfort and fatigue, but the exact consequences of these findings on the reduction or prevention of injuries have yet to be determined. The results may aid physical therapists and ergonomists in their evaluations of computer keyboard workstations and in making recommendations for interventions with regard to keyboard slope angle.

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569 Evaluation of platelete indices and count in ischemic heart diseaese patients compared to normal population

European Journal of Heart Failure Supplements ◽

10.1016/s1567-4215(05)80346-7 ◽

2005 ◽

Vol 4 (1) ◽

pp. 127-127

Keyword(s):

Normal Population ◽

Ischemic Heart

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On the admissibility and nonadmissibility of the usual estimator for the mean of multivariate normal population and conclusions to optimal design

Optimization ◽

10.1080/02331937408842218 ◽

1974 ◽

Vol 5 (7) ◽

pp. 591-597

Author(s):

H. Lätter

Keyword(s):

Optimal Design ◽

Normal Population ◽

Multivariate Normal ◽

Usual Estimator ◽

Multivariate Normal Population ◽

The Mean

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Myoelectric Activity Differences in Three Learning Sessions

Journal of Psychophysiology ◽

10.1027//0269-8803.16.2.92 ◽

2002 ◽

Vol 16 (2) ◽

pp. 92-96

Author(s):

Tiina Ritvanen ◽

Reijo Koskelo ◽

Osmo H„nninen

Keyword(s):

High School Students ◽

Muscle Activity ◽

Muscle Tension ◽

Emg Activity ◽

Traditional Learning ◽

Myoelectric Activity ◽

School Students ◽

Language Laboratory ◽

Upper Trapezius ◽

Muscle Groups

Abstract This study follows muscle activity in three different learning sessions (computer, language laboratory, and normal classroom) while students were studying foreign languages. Myoelectric activity was measured in 21 high school students (10 girls, 11 boys, age range 17-20 years) by surface electromyography (sEMG) from the upper trapezius and frontalis muscles during three 45-min sessions. Root mean square (RMS) average from both investigated muscles was calculated. The EMG activity was highest in both muscle groups in the computer-aided session and lowest in the language laboratory. The girls had higher EMG activity in both investigated muscle groups in all three learning situations. The measured blood pressure was highest at the beginning of the sessions, decreased within 10 min, but increased again toward the end of the sessions. Our results indicate that the use of a computer as a teaching-aid evokes more constant muscle activity than the traditional learning situations. Since muscle tension can have adverse health consequences, more research is needed to determine optimal classroom conditions, especially when technical aids are used in teaching.

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Personality of Clown Doctors

Journal of Individual Differences ◽

10.1027/1614-0001/a000187 ◽

2016 ◽

Vol 37 (1) ◽

pp. 49-55 ◽

Cited By ~ 5

Author(s):

Alberto Dionigi

Keyword(s):

General Population ◽

Personality Traits ◽

Big Five ◽

Normal Population ◽

Big Five Personality Traits ◽

Published Data ◽

Big Five Personality

Abstract. In recent years, both professional and volunteer clowns have become familiar in health settings. The clown represents a peculiar humorist’s character, strictly associated with the performer’s own personality. In this study, the Big Five personality traits (BFI) of 155 Italian clown doctors (130 volunteers and 25 professionals) were compared to published data for the normal population. This study highlighted specific differences between clown doctors and the general population: Clown doctors showed higher agreeableness, conscientiousness, openness, and extraversion, as well as lower neuroticism compared to other people. Moreover, specific differences emerged comparing volunteers and professionals: Professional clowns showed significantly lower in agreeableness compared to their unpaid colleagues. The results are also discussed with reference to previous studies conducted on groups of humorists. Clowns’ personalities showed some peculiarities that can help to explain the facility for their performances in the health setting and that are different than those of other groups of humorists.

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