Le système vestibulaire et le cortex moteur participent au contrôle de la posture, mais la nature de leurs interactions est peu documentée. Afin de caractériser les interactions vestibulo-corticales qui sous-tendent le contrôle de l’équilibre en position debout, l’activité électromyographique (EMG) du soléaire (SOL), du tibial antérieur (TA) et du péronier long (PERL) de la jambe droite a été enregistrée chez 14 sujets sains. La stimulation galvanique vestibulaire (GVS) a été appliquée avec la cathode derrière l’oreille droite ou gauche à différents intervalles inter-stimulus (ISIs) avant ou après la stimulation magnétique transcrânienne induisant des potentiels moteurs évoqués (MEPs) au niveau des muscles enregistrés. Lorsque que la cathode était à droite, une inhibition des MEPs a été observée au niveau du SOL à un ISI de 40 et 130 ms et une facilitation des MEPS a été observée au niveau TA à un ISI de 110 ms. Lorsque la cathode était à gauche, une facilitation des MEPs a été observée au niveau du SOL, du TA et du PERL à un ISI de 50, -10 et 0 ms respectivement. L’emplacement de ces interactions sur l’axe neural a été estimé en fonction des ISIs et en comparant l’effet de la GVS sur les MEPs à son effet sur l’EMG de base et sur le réflexe-H. Selon ces analyses, les modulations observées peuvent avoir lieu au niveau spinal ou au niveau supraspinal. Ces résultats suggèrent que les commandes de la voie corticospinale peuvent être modulées par le système vestibulaire à différents niveaux de l’axe neuronal. / The vestibular system and the motor cortex are involved in the control of posture but the nature of their interactions is poorly documented. To characterize vestibulo-cortical interactions underlying the control of balance during quiet standing, the electromyographic activity (EMG) of the soleus (SOL), tibialis anterior (TA) and peroneus longus (PERL) of the right leg was recorded in 14 healthy subjects. Bipolar galvanic vestibular stimulation (GVS) was applied with the cathode behind the right or left ear at various inter-stimulus intervals (ISI) before and after transcranial magnetic stimulation eliciting motor evoked potentials (MEP) in the muscles recorded. When the cathode was on the right, MEP in the SOL were inhibited at 40 and 130 ms while MEP were facilitated in TA at 110 ms. When the cathode was on the left, MEP were facilitated in the SOL at 50 ms, in TA at -10 ms and in PERL at 0 ms. The localization of these interactions along the neural axis was estimated according to the ISI and by comparing the effect of the GVS on the MEP to its effect on the background EMG and on the SOL H-reflex. Based on these analyses, the observed modulations of MEP observed could have occurred at spinal or supraspinal level. These results suggest that the corticospinal output may be modulated by the vestibular system at different levels of the neural axis.

The aim of the thesis was to find occupational therapy tests, or part thereof which could be used to test various inputs perception function of CNS. In cooperation with child and adult occupational therapists from Motol Hospital were researched occupational therapy various standardized tests designed to test children and adults. Then of them selected those tests (or a portion thereof) that contain the testing of individual sensory modalities of adult patients. Ultimately, these tests were applied to a group of adult population and evaluated. The whole work was compiled in the form of research. It was assumed that in the sets occupational therapy standardized tests, there are tests or parts that are able to focus their testing different modalities of perception function of the CNS within the cortical functions.

A transverse study in term newborns was made to determine the occurrence of motor responses and possible asymmetries during the stimulation of the vestibular system through the head turning after release from the midline and passive rotation. From October to December of 2005, 320 neonates were admitted to the Adjacent Lodgings of the University Hospital of Santa Maria. From those, 89 were selected for assessment of the vestibular function since they have previously had fetal static control through ultrasound. Our results show that right-sided head lateralization was significantly greater than left-sided. The predominancy of the lateralization towards the right side also occurred in the male gender, cephalic presentations and left-sided back, however, not significant. On the passive rotation about the vertical axis, the great majority of the neonates presented eye deviation in the opposite direction of the body movement and about the horizontal axis, the great majority of them either remained with their eyes closed or did not present any deviation at all. Results corroborate with the existing literature and suggest an association between fetal static and vestibular function. It was shown through vestibular stimulation trials that term newborns already possess a functional asymmetry as well as motor responses to this system stimulation / Com o objetivo determinar a ocorrência de respostas motoras e possíveis assimetrias durante a estimulação do sistema vestibular pelas provas de queda da cabeça e rotação passiva, foi realizado um estudo transversal no recém-nascido de termo. No período de outubro a dezembro de 2005, 320 recém-nascidos foram admitidos no Alojamento Conjunto do Hospital Universitário de Santa Maria, e destes 89 foram selecionados para avaliação da função vestibular, por terem feito controle da estática fetal através do ultra-som. Nossos resultados mostram que a lateralização da cabeça para a direita foi significativamente maior do que para esquerda. Este predomínio da lateralização para a direita também ocorreu no gênero masculino, nas apresentações cefálicas e com o dorso para esquerda, no entanto estes não foram significativos. Nas provas de rotação passiva na vertical a grande maioria dos RN apresentou o desvio dos olhos sempre no sentido oposto ao movimento do corpo e no plano horizontal, a grande maioria dos RN permaneceu com os olhos fechados, ou não apresentou desvio algum. Nossos resultados corroboram com a literatura existente, e sugerem uma associação entre a estática fetal e a função vestibular. Através das provas de estimulação vestibular, ficou demonstrado que o RN de termo já possui respostas motoras a estimulação deste sistema, bem como uma assimetria funcional

Les marsupiaux naissent très immatures, mais doivent atteindre une tétine, sans aide de la mère, à laquelle ils s’attachent pour poursuivre leur développement. Des informations sensorielles sont nécessaires pour s’orienter vers la tétine, la trouver, et s’y attacher. Le système vestibulaire, associé au sens de l’équilibre, a été proposé comme pouvant guider les petits marsupiaux vers la tétine en agissant sur les réseaux moteurs spinaux. Diverses études des marsupiaux suggèrent que le développement de ce système pourrait être suffisamment avancé pour influencer les comportements moteurs chez les nouveau-nés, mais son fonctionnement n’a jamais été testé. Pour le faire, nous avons soumis des opossums âgés de P0 (jour de la naissance; postnatal 0) à P21 à des stimulations vestibulaires et traité les tissus de la tête par immunohistochimie pour révéler c-Fos, utilisé comme indicateur d’activité neuronale. Du marquage dans les noyaux vestibulaires a été observé seulement à partir de P15. Pour confirmer ces résultats, nous avons effectué deux types d’expériences de stimulation sur des préparations in vitro d’opossums et enregistré les réponses motrices induites. Ainsi, des élévations de la tête n’ont pas permis de déceler de réponse suite aux stimulations aux âges étudiés (P4-P12). Par contraste, des pressions mécaniques directement appliquées sur le labyrinthe afin de stimuler les organes vestibulaires ont entrainé des réponses à tous les âges testés (P1-P9). Nos résultats suggèrent que la fonction du système vestibulaire est limitée par la maturité de ses organes sensoriels, et qu’il n’influence pas la motricité des nouveau-nés d’opossum en conditions physiologiques avant environ la fin de la 2e semaine de vie, même si les voies nerveuses entre les organes vestibulaires et la moelle épinière semblent déjà établies à la naissance. / Marsupials are born very immature, but must nevertheless find a teat, unaided by the mother, to which they attach to pursue their development. Sensory inputs are necessary to find the teat and attach to it, but the senses involved are still under discussion. The vestibular system, responsible for the sense of balance, was proposed as influencing motor behavior of newborns in various marsupial species by an action on spinal motor networks. Studies in the opossum Monodelphis domestica suggest that the development of the vestibular system could be advanced enough to influence locomotion at birth but its functionality has never been tested. To do that, we subjected intact opossums aged P0 (Postnatal day 0 ; day of birth) to P21 to vestibular stimulations and immunohistochemically processed their brain tissues to reveal c-Fos, used as a marker of neuronal activity. Immunoreactivity of neurons in the vestibular nuclei was observed only from P15 onwards. To confirm those results, we performed two series of experiments on in vitro preparations of newborn opossums, using stimulation of the vestibular apparatus and physiological recording of the induced motor responses Thus, vertical head tilts did not induce motor response at any of the ages studied (P4-P12). In contrast, mechanical pressure applied on the labyrinth to stimulate the vestibular organs induced motor responses at all ages studied (P1-P9). Our results suggest that the vestibular system’s function is limited by the maturity of its sensory organs and that it can’t influence motor activity in physiological condition before the end of the 2nd postnatal week, even if functional pathways from the labyrinth to the spinal cord seem to be already in place at birth.

Adolescent idiopathic scoliosis (AIS) is characterised as a three-dimensional deformity of the spine with unknown etiopathogenesis. There is evidence that scoliosis may be associated with abnormalities of the vestibular system. Examination of postural stability and verticality perception is a way to assess vestibular function. The objective of this work is to compare postural stability and subjective visual vertical (SVV) between adolescents with idiopathic scoliosis and healthy controls. Twelve AIS patients and twelve controls participated in the study. Examination of postural stability was performed through a Kistler force platform and the SVV was tested using a pre-programmed computed equipment Synapsys. An instrument for evaluating the perception patients have of their trunk deformity, Trunk Appearance Perception Scale (TAPS), was also part of the examination. Our results did not show a significant difference between the two groups in postural stability and static SVV-S. Statistically significant difference was found on dynamic SVV-D with clockwise rotation (p  0,01): AIS patients (1,19ř ± 1,03ř), control group (-0,17ř ± 0,82ř). There was also a significant difference on absolute deviation of dynamic SVV-D with clockwise rotation (p  0,05): AIS patients (1,50ř ± 0,77ř), control group (0,81ř ±...

INTRODUCTION: La stimulation vestibulaire galvanique (GVS) est utilisée pour évaluer l’intégrité du système vestibulaire et améliorer notre compréhension des mécanismes de l‘équilibre. Néanmoins les réponses évoquées montrent une grande variabilité interindividuelle ce qui rend la compréhension du rôle du système vestibulaire difficile. OBJECTIF: Développer un protocole d’évaluation d’un seuil vestibulaire objectif spécifique à la personne. MÉTHODES: Dix-huit sujets sains droitiers se tenaient debout sur une plate-forme de force, les yeux fermés, la tête vers l’avant. L’accélération de la tête était enregistrée lorsque la GVS (durée: 200 ms) était appliquée à des intensités de 1 à 4,5mA. Des courbes de recrutement ont été générées afin de déterminer le seuil objectif (T). Puis, les participants ont été stimulés à différentes intensités relatives au seuil (0,5T; 0,75T; 1T et 1,5T). L’aire de l’ellipse de confiance (AE) à 95%, la vitesse de déplacement du centre de pression (CoP) et l’activité électromyographique du soléaire (SOL) ont été mesurées. RÉSULTATS: 1) Un seuil objectif a été déterminé pour chaque sujet basé sur l’accélération de la tête. 2) L’aire de l’ellipse, pendant la stimulation, corrélait avec l’intensité de stimulation (r=0,95; p=0,03). 3) L’amplitude de la 1ère phase du patron triphasique de la vitesse de déplacement du CoP corrélait aussi avec l’intensité de stimulation (r=0,98; 0,04). 4) En plus, l’amplitude de la réponse musculaire à moyenne latence induite par la GVS sur le SOL montrait une corrélation significative avec l’intensité de stimulation (r=0,7; p=0,045). DISCUSSION: Un seuil objectif vestibulaire peut être identifié par un accéléromètre. Les réponses vestibulaires mesurées par l’AE et le CoP sont proportionnelles aux intensités de stimulation relatives au seuil objectif déterminé. / INTRODUCTION: Galvanic vestibular stimulation (GVS) is used to assess the integrity of the vestibular system and to improve our understanding of the mechanisms of balance. However, the GVS-induced responses show great inter-individual variability, which makes it difficult to understand the contribution of the vestibular system in maintaining balance. OBJECTIVE: To develop a protocol identifying an objective vestibular threshold for GVS in order to limit this variability observed on GVS-induced responses. METHODS: Eighteen healthy right-handed subjects stood on a force platform, eyes closed, head forward. The head acceleration was recorded when the GVS (duration: 200 ms) was applied at intensities varying between 1 and 4.5mA. Recruitment curves were reconstructed to determine the objective threshold (T). Then, the participants were stimulated at different intensities relative to threshold (0.5T; 0.75T; 1T and 1.5T). The 95% confidence ellipse area, the velocity of the center of pressure (CoP) displacement and the electromyographic activity of the soleus muscle (SOL) were measured. RESULTS: 1) An objective threshold was determined for each subject based on the acceleration of the head. 2) The area of the ellipse, during stimulation, correlated with the stimulation intensity (r = 0.95; p = 0.03). 3) The amplitude of the 1st peak of the three-phase CoP velocity pattern also correlated with the stimulation intensity (r = 0.98; 0.04). 4) In addition, the amplitude of the medium latency response induced by the GVS on the SOL showed a significant correlation with the stimulation intensity (r = 0.7; p = 0.045). DISCUSSION: An objective vestibular threshold can be identified by an accelerometer. The vestibular responses measured by the ellipse area and the CoP are proportional to the stimulation intensities relative to the determined objective threshold.

Despite our understanding of the impact of noise-induced damage to the auditory system, much less is known about the impact of noise exposure on the vestibular system. In this article, we review the anatomical, physiological, and functional evidence for noise-induced damage to peripheral and central vestibular structures. Morphological studies in several animal models have demonstrated cellular damage throughout the peripheral vestibular system and particularly in the otolith organs; however, there is a paucity of data on the effect of noise exposure on human vestibular end organs. Physiological studies have corroborated morphological studies by demonstrating disruption across vestibular pathways with otolith-mediated pathways impacted more than semicircular canal-mediated pathways. Similar to the temporary threshold shifts observed in the auditory system, physiological studies in animals have suggested a capacity for recovery following noise-induced vestibular damage. Human studies have demonstrated that diminished sacculo-collic responses are related to the severity of noise-induced hearing loss, and dose-dependent vestibular deficits following noise exposure have been corroborated in animal models. Further work is needed to better understand the physiological and functional consequences of noise-induced vestibular impairment in animals and humans.

The ability to perceive the Earth's magnetic field has been demonstrated in a variety of animals, including representatives of all five classes of vertebrates. The physiological mechanisms underlying magnetic field sensation, however, remain largely unknown. Behavioral, physiological, neuroethological studies and studies using early response genes as neuronal activation markers indicated that a major role in the perception and processing of magnetic information play trigeminal, vestibular and visual systems. Subsequently, magnetic information seem to be integrated with multimodal sensory and motor information within the hippocampal-entorhinal system. In the majority of studies, however, birds have been used as model organisms. In this work I analyzed the neural substrate of magnetic compass orientation in the mouse strain C57BL/6J using markers c-Fos and Egr1. I found that all the aforementioned systems contain neurons responsive to the experimental magnetic fields. This finding demonstrates a complex processing of the magnetic information at level of the central nervous system.

Author: Anna Šalbabová Title: Influence of acrobatic sports on dynamic postrual stability Objectives: The aim of this study is to evaluate an influence of acrobatic sports on dynamic postural stability with greater focus on vestibular system and reaction time of the subjects and to compare those qualities with non-acrobatic subjects who have no history of acrobatic training. Methods: Assessments were performed on NeuroCom Smart Equi Test device, which is located in laboratory of kinesiology at the UK FTVS. There were 20 subjects divided into 2 groups 10 subject each. One group made of 10 acrobatic athletes, the second group of 10 non- acrobatic subjects with no history of acrobatic training. The age of all subjects ranges from 20 to 34 years. For the testing of dynamic postural stability were used Sensory Organization Test (SOT), Motor Control Test (MCT), Head Shake - Sensory Organization Test (HS-SOT). For assessment of vestibulo-ocular reflex was used Dynamic Visual Acuity Test (DVAT), which cannot be performed without Perception Time Test (PPT). Results: The results have shown significantly better reaction times of acrobatic group in MCT and better results of acrobatic group in Head Shake - SOT in half of the performed tests. SOT and DVAT have shown no significant data. Conclusion: This study...

Purpose: The purpose of this study was to evaluate the effectiveness of triaging patients with motion-provoked dizziness into a benign paroxysmal positional vertigo (BPPV) clinic. Method: A retrospective chart review was performed of veterans who were tested and treated for BPPV in a triaged BPPV clinic and veterans who were tested and treated for BPPV in a traditional vestibular clinic. Results: The BPPV triage clinic had a hit rate of 39%. On average, the triaged BPPV clinic reduced patient wait times by 23 days relative to the wait times for the traditional vestibular clinic while also reducing patient costs. Conclusion: Triaging patients with BPPV is one method to improve access to evaluation and treatment and a mechanism for the effective use of clinic time and resources.