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Results for “REFLEX, PROPRIOCEPTIVE”

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At least 433 records · Page 24Linked to original sources
PubMed1996

Interaction between the vestibular, optical, and proprioceptive sensory systems during realization of rotary nystagmus.

Questions related to the rotary nystagmus generation in the different variants of interactions between the vestibular, optical, and proprioceptive sensory systems are considered. A physiological concept of the opto-vestibulo-cervical system is given. The biological expediency of nystagmus is considered. It is proved that nystagmus is the organism's position-finding (orientation) reaction directed to a search for the objects in space aiding human orientation. Certain ideas about the vestibulology and physiology of space perception are discussed in detail from the viewpoint of the integral system approach.

Adolescent↗
PubMed2001

Concept of spastic hypertonia.

This introductory article highlights the definition of spastic hypertonia, and briefly introduces the reader to the incidence and most frequent causes of spastic hypertonia. The article also discusses the functional losses caused by spastic hypertonia that will be reviewed more thoroughly in the following articles. Also discussed is the neural physiology and the locations of the structural lesions within the central nervous system that are involved in spastic hypertonia, with an emphasis on the different clinical presentations depending on the location of the lesion.

Humans↗
PubMed2002

[Stabilimetry and cranio-cervico-mandibular disorders].

BACKGROUND: Cranio-cervico-mandibular disorders can cause disturbances in posture. Stabilimetry measures spatio-temporal variations in the center of body pressure and evaluates the mechanisms of maintenance of balance. The study used a stabilimetric platform to evaluate posture changes in patients with cranio-cervico-mandibular disorders before and after treatment for malocclusion. METHODS: Between February 1998 and December 2000, 60 patients with cranio-cervico-mandibular disorders were recruited from the Dentistry Clinic of the University of Sassari. Each patient underwent two stabilimetric examinations (closed mouth with cotton wads inserted between the dental arches). The tests were conducted on a stabilimetric platform. Measurement of body posture load and sway were analyzed with a specific software program that correlated the vestibular, somatosensory and visual systems, and determined the role of each in postural control. RESULTS: The stabilimetric analysis showed that the adoption of the plaque allowed rebalance of the postural system, without affecting the visual system. After treatment, 64% of patients experienced remission of pain symptoms with orthotic therapy. CONCLUSIONS: The relationship between malocclusion and posture should be seen from a holistic standpoint in other to gain a global therapeutic outcome.

Adolescent↗
PubMed1993

Human space experiments in SL-J: preparation and conducted.

This experiment investigated how human beings achieve visual stability during body movements, including fine motion on the ground. When humans are exposed to an environment with different gravity vectors, the programmed behavior on the ground must be changed, that is, it is reprogrammed. This is called habituation or familiarization. This experiment focuses on visual, vestibular and somatosensory perception coordination and how it changes in microgravity as compared to a 1-G environment. We examined these issues under microgravity during the mission Spacelab Japan [correction of Japane] (SL-J) mission with the cooperation of the Japanese Payload Specialist (PS), Dr. Mohri. In this paper we describe how the first human life science experiments were conducted and how the data processed is being.

Adaptation, Physiological↗
PubMed2003

Spinal cats on the treadmill: changes in load pathways.

Treadmill training and clonidine, an alpha-2 noradrenergic agonist, have been shown to improve locomotion after spinal cord injury. We speculate that transmission in load pathways, which are involved in body support during stance, is specifically modified by training. This was evaluated by comparing two groups of spinal cats; one group (n = 11) was trained to walk until full-weight-bearing (3-4 weeks), and the other (shams; n = 7) was not. During an acute experiment, changes in group I pathways, monosynaptic excitation, disynaptic inhibition, and polysynaptic excitation were investigated by measuring the response amplitude in extensor motoneurons before and after clonidine injection. Monosynaptic excitation was not modified by clonidine but was decreased significantly by training. Disynaptic inhibition was significantly decreased by clonidine in both groups, but more significantly in trained cats, and significantly reduced by training after clonidine. Also, clonidine could reverse group IB inhibition into polysynaptic excitation in both groups but more frequently in trained cats. We also investigated whether fictive stepping revealed additional changes. In trained cats, the phase-dependent modulation of all three responses was similar to patterns reported previously, but in shams, modulation of monosynaptic and polysynaptic responses was not. Overall, training appears to decrease monosynaptic excitation and enhance the effects of clonidine in the reduction of disynaptic inhibition and reversal to polysynaptic excitation. Because it is believed that polysynaptic excitatory group I pathways transmit locomotor drive to extensor motoneurons, we suggest that the latter changes would facilitate the recruitment of extensor muscles for recovering weight-bearing during stepping.

Adrenergic alpha-Agonists↗
PubMed2005

Human ocular torsion and perceived roll responses to linear acceleration.

We investigated if human ocular torsion (OT) and perceived roll (PR) are elicited in response to either dynamic interaural linear acceleration or dynamic roll tilt of the gravito-inertial force (GIF). We expanded a previous study [26] that measured only OT across a limited frequency-range (from 0.35 Hz to 1 Hz) by simultaneously measuring OT and PR at three very low (0.01, 0.02 and 0.05 Hz) and one high (1 Hz) frequencies. Three experimental conditions were investigated: (1) Y-Upright with acceleration along the interaural (Y) axis while upright, (2) Y-Supine with acceleration along the Y-axis while supine, and (3) Z-RED with acceleration along the rostro-caudal Z) axis with right-ear-down (RED). OT was measured by video-oculography, while PR was measured by use of a somatosensory bar. OT and PR were qualitatively different. Large OT responses were measured for Y-Upright and Y-Supine, while large perceived roll responses were observed for Y-Upright and Z-RED. OT for Z-RED was small, and PR for Y-Supine was absent. In conclusion, OT and PR appear governed by qualitatively different neural mechanisms. OT appears mostly influenced by central low-pass filtering of interaural graviceptor cues, while PR appears mostly influenced by roll tilt of the GIF.

Acceleration↗
PubMed1990

[Experimental studies on the influences of physical properties of foods on the appearance of silent period in discharge of masticatory muscles].

UNLABELLED: It is considered that the appearance of Silent Period (SP) during food crushing may relieve tissue injury caused by sudden change of maxillo-mandibular impactive force. In connection with this phenomenon, the relation between changes in vertical velocity of mandibular movement and the appearance of SP during food crushing was investigated. In addition, efforts were made to clarify the influences of lack of periodontal pressoreceptive information on the appearance of SP. Subjects were ten males (aged 24 to 31) with natural dentition and no masticatory dysfunction. Electromyograms were recorded on 4 lead locations: the central parts of each masseter and the anterior bundles of each temporal muscle. A Mandibular Kinesiograph and electromyograph were used to record simultaneously mandibular movement and myoelectric discharge during food crushing for the sake of comparing changes in mandibular position, vertical velocity of mandibular movement and muscular activity. Eight kinds of foods of various textures were selected for use in the examinations: dry macaroni, rice cracker, raw carrot, pickled thistle root, pickled radish, raisin, synthetic rubber block and softened chewing gum. The food was positioned on the occlusal table of the lower first molar on the habitual masticatory side of each subject. Then the subject was required to close his mouth rapidly to crush the food at a single masticatory stroke. Two experimental conditions were established in order to clarify the significance of periodontal pressoreceptive information on the appearance of SP: (1) normalcy and (2) infiltration anesthesia of the periodontal tissues of the upper and lower first-molar region on the habitual masticatory side. Results 1. SP appeared during a single masticatory stroke in response to sudden decreases or increases of vertical velocity of mandibular movement. 2. The frequency of the appearance of SP depends on the crushing characteristics of the food which is tested. For softened chewing gum and the synthetic rubber block, only one SP occurred; two SPs occurred in the cases of pickled radish and raisin; three SPs in the cases of raw carrot and pickled thistle root; and more than four SPs in the cases of dry macaroni and rice cracker. 3. Lack of periodontal pressoreceptive information resulting from anesthesia had no effect on the appearance of SP. CONCLUSIONS: 1. Sudden changes in vertical velocity of mandibular movement may depend on the crushing characteristics of the food which is crushed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMedDate not supplied

[The role of vestibular and proprioceptive afferent pathways in the reaction to pushing (author's transl)].

The reaction to pushing was studied in 6 normal subjects and 3 patients with bilateral peripheral vestibular lesions. The reaction to pushing was tested on the anterior tibial and soleus, by modifying the proprioceptive afferent impulses. The respective parts of the vestibular, proprioceptive, visual components, and of a sudden, start are analyzed; the afferent impulses obtain information from the initial posture and modulate the relative importance of these different factors at a supra-segmentary level.

Afferent Pathways↗
PubMed1986

[Status of muscle tone in rheumatoid arthritis patients].

Muscle tonus in patients with rheumatoid arthritis (RA) was collated with the activity of the pathological process and functional articular insufficiency (FAI) in different variants of polyneuropathy (P). Hetero- or unidirectional hypotension of muscles was the most characteristic sign in RA. In cases of the sensory variant of P, patients with an early period of the disease and 1-0 degree FAI showed severe damage to the central motor neuron, linked with a dissociated type of muscular dystonia (predominantly hypotension of the flexory group of legs) and a peculiar dystonic phenomenon (a vestibular-cerebellar positioning of the wrist). This kind of wrist positioning was directly correlated with the side of the predominant damage to the central motor neuron. In cases of sensory-motor forms of P, patients with degree II-III FAI, in whom lesions to the peripheral motor neuron were predominant, developed unidirectional muscle hypotension. EMG findings served as an adequate reflection of the nature of changes in the muscle tonus.

Adult↗
PubMed1986

[Relation between parameters of efferent activity and limb position during fictive scratching in the decerebrate cat].

The influence of tonic afferent inflow conditioned by ipsilateral hindlimb position on the spinal generator of scratching efferent activity parameters was investigated in immobilized decerebrated cats. When the afferent inflow was absent (after the hindlimb deafferentation) strong correlation between the motor activity parameters of successive "scratch" cycles was observed. In case of the intact afferentation this correlation was somewhat weaker and decreased with shifting the hindlimb from the aimed position to overaimed or deflecting backward. The discovered statistically significant correlations between the parameters of different motor activity phases and their dependence on the hindlimb position are organized in such a way that they can provide stability of the aimed position of the hindlimb carrying out oscillatory movements. According to the parameters of the efferent activity and their correlation type, the hindlimb deafferentation is most similar to the aimed position of the hindlimb.

Animals↗