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Results for “Muscle Tonus”

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At least 73 records · Page 4Linked to original sources
PubMed1987

Variations in nuchal muscle tonus following paradoxical sleep deprivation in the rabbit.

Although tonic inhibition of nuchal or facial musculature is considered an intrinsic component of paradoxical sleep (PS) in mammals, this inhibition is either absent or greatly attenuated in the rabbit. To further explore the characteristics of this phenomenon in this species, variations in quantified nuchal muscle activity were examined before, during and following 24 h of PS deprivation. It was postulated that if the substrate for PS-associated tonic electromyogram (EMG) inhibition is present, this procedure--which is known to affect both tonic and phasic components of PS--might enhance such inhibition. For these investigations chronically implanted rabbits (electroencephalographic, eye movement and nuchal muscle placements) were recorded continuously for 5 consecutive days (two day baseline, one day deprivation, two day recovery). Muscle activity was quantified by resetting integration techniques and comparisons made of activity levels before, during and after PS episodes across conditions. The deprivation procedure significantly reduced the amount of PS relative to baseline values, and a significant PS increase (rebound) occurred during postdeprivation recordings. Across-condition EMG-related effects included the corroboration of previous reports of an absence of nuchal atonia during PS, a significant diurnal variation in EMG activity--with greater activity occurring during the dark portion of the light-dark cycle, and enhanced activity immediately following PS episodes relative to either pre-PS or PS levels. Deprivation-related changes in quantified EMG activity included a pre-PS decrease during both the last 12 h of deprivation and the initial 12 h of recovery sleep, and an enhancement of EMG activity during PS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

[Clinical electromyography and several problems in the neurophysiology of muscle tonus in man].

On the basis of a summarization of long-term studies of the different types of tonic reactions in normals and patients with different forms of dystonia, the author describes 7 types of such reactions. The paper deals as well as with possible physiological and pathophysiological mechanisms of their occurrence and the significance of these data for the theoretical analysis of the regulation of the human muscular tone.

Electromyography↗
PubMedDate not supplied

[Muscle tonus in rigidity and spasticity].

The results of the examination of the muscle tone by passive movement of the extremity at a low and high rate in patients with spasticity are discussed. In parkinsonism high resistance was noted to passive movements of the extremity at a low rate (with a period of oscillatory movement of 100 s and more) as well as in the first cycles of rapid sinusoidal movement (with a period of 1 s) if the extremity had been at rest for a lengthy period of time. In spasticity of other etiology, there was a gradual increase of the amplitude on the mechanomyogram in high rates of passive movements, which was evidently due to growth of stimulation in the stretch-reflex arc from cycle to cycle as the result of sumation with trace stimulation from the preceding cycles. The shape of the spectromechanomyogram, which is marked by a rise in the region of the high rates, is considered to be a sign of spasticity, whereas the size of this rise is accepted as a quantitative index of the spastic component of the muscle tone.

Electromyography↗
PubMed1974

The effects of electrical stimulation of VL and sub-VL on muscle tonus.

VL and sub-VL were electrically stimulated at 1-mm intervals and the influence on three muscles (anterior tibial muscle, gastrocnemius muscle and soleus muscle) of the contralateral limb was studied by the method of RE-EMG. The effect of VL and sub-VL stimulation was examined on ether clonus as an indicator of hyperactive muscle, especially for spasticity. The results are summarized as follows: 1. Clonus was apparently suppressed by electrical stimulation in an area (F, 10.0 mm; L, 4.0 mm; D, from +2 to -2; there was especially marked suppression of clonus by stimulation in sub-VL. 2. On electrical stimulation of the lateral third of VL, hypertonicity of anterior tibial muscle (T), hypotonicity of gastrocnemius muscle (G), and also hypotonicity of soleus muscle (S), was observed on stimulation of the middle third, T, G, S, and of the medial third, no effect was observed. 3. Electrical stimulation of the anterior part of VL showed T, G, S, and electrical stimulation of the posterior part of VL showed T, G, S.

Animals↗
PubMed1983

[Hyperventilatory hypocapnia and muscle tonus].

It has been established that hyperventilation hypocapnia inhibits the postural tone in both the unrespiratory and respiratory muscles. However, muscle excitability increases at the same time. As a result phasic as well as tonic reflexes in response to additional nervous stimuli are facilitated in the presence of hypocapnia.

Animals↗