scholarly journals Velocity of body lean evoked by leg muscle vibration potentiate the effects of vestibular stimulation on posture

2007 ◽  
pp. 829-832
Author(s):  
O Dzurková ◽  
F Hlavačka

To investigate the vestibular and somatosensory interaction in human postural control, a galvanic vestibular stimulation of cosine bell shape resulting in a small forward or backward body lean was paired with three vibrations of both soleus muscles. The induced body lean was registered by the position of the center of foot pressure (CoP). During a quiet stance with eyes closed the vibration of both soleus muscles with frequency (of) 40 Hz, 60 Hz and 80 Hz resulted in the body lean backward with velocities related to the vibration frequencies. The vestibular galvanic stimulation with the head turned to the right caused forward or backward modification of CoP backward response to the soleus muscles vibration and peaked at 1.5-2 s following the onset of the vibration. The effect of the paired stimulation was larger than the summation of the vestibular stimulation during the quiet stance and a leg muscle vibration alone. The enhancement of the galvanic stimulation was related to the velocity of body lean induced by the leg muscle vibration. The galvanic vestibular stimulation during a faster body movement had larger effects than during a slow body lean or the quiet stance. The results suggest that velocity of a body postural movement or incoming proprioceptive signal from postural muscles potentiate the effects of simultaneous vestibular stimulations on posture.

2007 ◽  
Vol 17 (1) ◽  
pp. 47-62
Author(s):  
Per-Anders Fransson ◽  
Magnus Hjerpe ◽  
Rolf Johansson

Control of orthograde posture and use of adaptive adjustments constitutes essential topics of human movement control, both in maintenance of static posture and in ensuring body stability during locomotion. The objective was to investigate, in twelve normal subjects, how head, shoulder, hip and knee movements and torques induced towards the support surface were affected by vibratory proprioceptive and galvanic vestibular stimulation, and to investigate whether movement pattern, body posture and movement coordination were changed over time. Our findings suggest that the adaptive process to enhance stability involves both alteration of the multi-segmented movement pattern and alteration of body posture. The magnitude of the vibratory stimulation intensity had a prominent influence on the evoked multi-segmented movement pattern. The trial conditions also influenced whether the posture were altered and if these posture adjustments were done directly at stimulation onset or gradually over a longer period. Moreover, the correlation values showed that the subjects, primarily during trials with vibratory stimulation alone, significantly increased the body movement coordination at stimulation onset and maintained this movement pattern throughout the stimulation period. Furthermore, when exposed to balance perturbations the test subjects synchronized significantly the head and torso movements in anteroposterior direction during all trial conditions.


Author(s):  
Youstina Mikhail ◽  
Jonathan Charron ◽  
Jean-Marc Mac Thiong ◽  
Dorothy Barthélemy

Galvanic vestibular stimulation (GVS) is used to assess vestibular function, but vestibular responses can exhibit variability depending on protocols or intensities used. We measured head acceleration in healthy subjects to identify an objective motor threshold on which to base GVS intensity when assessing postural responses. Thirteen healthy right-handed subjects stood on a force platform, eyes closed, head facing forward. An accelerometer was placed on the vertex to detect head acceleration, and electromyography activity of the right soleus was recorded. GVS (200 ms; current steps 0.5;1-4mA) was applied in a binaural and bipolar configuration. 1) GVS induced a biphasic accelerometer response at a latency of 15 ms. Based on response amplitude, we constructed a recruitment curve for all participants and determined the motor threshold. In parallel, the method of limits was used to devise a more rapid approach to determine motor threshold. 2) We observed significant differences between motor threshold based on therecruitment curve and perceptual thresholds (sensation/perception of movement). No significant difference was observed between the motor threshold based on the method of limits and perceptual thresholds . 3) Using orthogonal polynomial contrasts, we observed a linear progression between multiples of the objective motor threshold (0.5, 0.75, 1, 1.5x motor threshold) and the 95% confidence ellipse area, the first peak of center of pressure velocity, and the short and medium latency responses in the soleus. Hence, an objective motor threshold and a recruitment curve for GVS were determined based on head acceleration, which could increase understanding of the vestibular system.


2017 ◽  
Vol 118 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Johannes Keyser ◽  
W. Pieter Medendorp ◽  
Luc P. J. Selen

When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is unknown whether vestibular feedback is specifically processed dependent on the behavioral goal. Here, we studied whether vestibular signals evoke fixed responses with the aim to preserve the hand trajectory in space or are processed more flexibly, correcting trajectories only in task-relevant spatial dimensions. We used galvanic vestibular stimulation to perturb reaching movements toward a narrow or a wide target. Results show that the same vestibular stimulation led to smaller trajectory corrections to the wide than the narrow target. We interpret this reduced compensation as a task-dependent modulation of vestibular feedback responses, tuned to minimally intervene with the task-irrelevant dimension of the reach. These task-dependent vestibular feedback corrections are in accordance with a central prediction of optimal feedback control theory and mirror the sophistication seen in feedback responses to mechanical and visual perturbations of the upper limb. NEW & NOTEWORTHY Correcting limb movements for external perturbations is a hallmark of flexible sensorimotor behavior. While visual and mechanical perturbations are corrected in a task-dependent manner, it is unclear whether a vestibular perturbation, naturally arising when the body moves, is selectively processed in reach control. We show, using galvanic vestibular stimulation, that reach corrections to vestibular perturbations are task dependent, consistent with a prediction of optimal feedback control theory.


2020 ◽  
Vol 14 ◽  
Author(s):  
Akiyoshi Matsugi ◽  
Kosuke Oku ◽  
Nobuhiko Mori

Objective: This study aimed to investigate whether galvanic vestibular stimulation with stochastic noise (nGVS) modulates the body sway and muscle activity of the lower limbs, depending on visual and somatosensory information from the foot using rubber-foam.Methods: Seventeen healthy young adults participated in the study. Each subject maintained an upright standing position on a force plate with/without rubber-foam, with their eyes open/closed, to measure the position of their foot center of pressure. Thirty minutes after baseline measurements under four possible conditions (eyes open/closed with/without rubber-foam) performed without nGVS (intensity: 1 mA, duration: 40 s), the stimulation trials (sham-nGVS/real-nGVS) were conducted under the same conditions in random order, which were then repeated a week or more later. The total center of pressure (COP) path length movement (COP-TL) and COP movement velocity in the mediolateral (Vel-ML) and anteroposterior (Vel-AP) directions were recorded for 30 s during nGVS. Furthermore, electromyography activity of the right tibial anterior muscle and soleus muscle was recorded for the same time and analyzed.Results: Three-way analysis of variance and post-hoc multiple comparison revealed a significant increment in COP-related parameters by nGVS, and a significant increment in soleus muscle activity on rubber. There was no significant effect of eye condition on any parameter.Conclusions: During nGVS (1 mA), body sway and muscle activity in the lower limb may be increased depending not on the visual condition, but on the foot somatosensory condition.


2021 ◽  
pp. 1-15
Author(s):  
Samar Babaee ◽  
Moslem Shaabani ◽  
Mohsen Vahedi

BACKGROUND: Galvanic vestibular stimulation (GVS) is believed to be one of the most valuable tools for studying the vestibular system. In our opinion, its combined effect on posture and perception needs to be examined more. OBJECTIVE: The present study was conducted to investigate the effect of a 20 Hz sinusoidal Galvanic Vestibular Stimulation (sGVS) on the body sway and subjective visual vertical (SVV) deviation through two sets of electrode montages (bipolar binaural and double temple-mastoidal stimulation) during a three-stage experiment (baseline, threshold, and supra-threshold levels). METHODS: While the individuals (32 normal individuals, 10 males, the mean age of 25.37±3.00 years) were standing on a posturography device and SVV goggles were put on, the parameters of the body sway and SVV deviation were measured simultaneously. Following the baseline stage (measuring without stimulation), the parameters were investigated during the threshold and supra-threshold stages (1 mA above the threshold) for 20 seconds. This was done separately for each electrode montage. Then, the results were compared between the three experimental stages and the two electrode montages. RESULTS: In both electrode montages, “the maximum amplitude” of the mediolateral (ML) and anteroposterior (AP) body sway decreased and increased in the threshold and supra-threshold stages, respectively, compared to the baseline stage. Comparison of the amount of  “amplitude change” caused by each electrode montages showed that the double temple-mastoidal stimulation induced a significantly greater amplitude change in body sway during both threshold and supra-threshold stages (relative to the baseline stage). The absolute mean values of the SVV deviation were significantly different between the baseline and supra-threshold levels in both electrode montages. The SVV deviation in double temple-mastoidal stimulation was a bit greater than that in the bipolar binaural stimulation. CONCLUSION: Double temple-mastoidal stimulation has induced greater amount of change in the body sway and SVV deviation. This may be due to the more effective stimulation of the otoliths than semicircular canals.


1995 ◽  
Vol 73 (2) ◽  
pp. 896-901 ◽  
Author(s):  
J. T. Inglis ◽  
C. L. Shupert ◽  
F. Hlavacka ◽  
F. B. Horak

1. We investigated the role of the vestibular system in postural control by combining galvanic vestibular stimulation (0.2-0.5 mA) with platform translations in standing subjects. Vestibular stimulation delivered 500 ms before and continuously during the platform translation produced little change in the earliest center of pressure (COP) and center of mass (COM) movements in response to platform translations, but resulted in large changes during the execution of the postural movement and in the final equilibrium position. 2. Vestibular stimulation produced anterior or posterior shifts in the position of COP and COM, depending on the polarity of the galvanic current. These shifts were larger during platform translations than during quiet stance. The peak of these shifts in COP and COM occurred at 1.5-2.5 s after the onset of platform translation, and increased in magnitude with increasing platform velocity. The final equilibrium positions of COP and COM were also shifted, but these shifts were smaller and not dependent on platform velocity. 3. These results imply that a tonic step of galvanic current to the vestibular system can change the final equilibrium position for an automatic postural response. Furthermore, these results indicate that the vestibular system may play a larger role in interpreting sensory reafference during postural movements, and especially during fast postural movements, than in controlling quiet stance. Finally, these results indicate that the vestibular system does not play a critical role in triggering the earliest postural responses, but it may be critical in establishing an internal reference for verticality.


2021 ◽  
Author(s):  
Taro Fujimaki ◽  
Masanori Wako ◽  
Kensuke Koyama ◽  
Naoto Furuya ◽  
Ryoji Shinohara ◽  
...  

AbstractFloating toe (FT) is a frequently seen condition in which a toe is inadequately in contact with the ground. Although toes play an important role in stabilizing standing posture and walking, many aspects of the effects of FT on the body remain unclear. To our knowledge, there have been no reports about the relationship between FT and postural stability, especially in children. This study aimed to clarify the prevalence of FT and its relationship with static postural stability in children. Of the 400 children aged 8 years who participated in our cohort study, 396, who were examined for static postural stability, were included in this study. Postural stability and FT were assessed using a foot pressure plate. The sway path length of the center of pressure and the area of the ellipse defined as the size of the area marked by the center of pressure were measured as an evaluation of static postural stability. We calculated the “floating toe score (FT score: small FT score indicates insufficient ground contact of the toes)” using the image of the plantar footprint obtained at the postural stability measurement. The FT rate was very high at more than 90%, and the FT score in the eyes-closed condition was significantly higher than that in the eyes-open condition in both sexes. The FT score significantly correlated with the center of pressure path and area. Our results suggest that ground contact of the toes is not directly related to static postural stability in children, but it may function to stabilize the body when the condition becomes unstable, such as when the eyes are closed.


2020 ◽  
Vol 123 (5) ◽  
pp. 2010-2023 ◽  
Author(s):  
Etienne Guillaud ◽  
Céline Faure ◽  
Emilie Doat ◽  
Laurent J. Bouyer ◽  
Dominique Guehl ◽  
...  

This study addresses the extent of conservation of trunk muscle control in humans. Results show that galvanic vestibular stimulation-evoked vestibular responses in trunk muscles remain strong in conditions where leg muscle responses are downmodulated (walking, standing, microgravity). This suggests a phylogenetically conserved blueprint of sensorimotor organization, with strongly hardwired vestibulospinal inputs to axial motoneurons and a higher degree of flexibility in the later emerging limb control system.


1998 ◽  
Vol 80 (5) ◽  
pp. 2699-2709 ◽  
Author(s):  
Elie Lobel ◽  
Justus F. Kleine ◽  
Denis Le Bihan ◽  
Anne Leroy-Willig ◽  
Alain Berthoz

Lobel, Elie, Justus F. Kleine, Denis Le Bihan, Anne Leroy-Willig A, and Alain Berthoz. Functional MRI of galvanic vestibular stimulation. J. Neurophysiol. 80: 2699–2709, 1998. The cortical processing of vestibular information is not hierarchically organized as the processing of signals in the visual and auditory modalities. Anatomic and electrophysiological studies in the monkey revealed the existence of multiple interconnected areas in which vestibular signals converge with visual and/or somatosensory inputs. Although recent functional imaging studies using caloric vestibular stimulation (CVS) suggest that vestibular signals in the human cerebral cortex may be similarly distributed, some areas that apparently form essential constituents of the monkey cortical vestibular system have not yet been identified in humans. Galvanic vestibular stimulation (GVS) has been used for almost 200 years for the exploration of the vestibular system. By contrast with CVS, which mediates its effects mainly via the semicircular canals (SCC), GVS has been shown to act equally on SCC and otolith afferents. Because galvanic stimuli can be controlled precisely, GVS is suited ideally for the investigation of the vestibular cortex by means of functional imaging techniques. We studied the brain areas activated by sinusoidal GVS using functional magnetic resonance imaging (fMRI). An adapted set-up including LC filters tuned for resonance at the Larmor frequency protected the volunteers against burns through radio-frequency pickup by the stimulation electrodes. Control experiments ensured that potentially harmful effects or degradation of the functional images did not occur. Six male, right-handed volunteers participated in the study. In all of them, GVS induced clear perceptions of body movement and moderate cutaneous sensations at the electrode sites. Comparison with anatomic data on the primate cortical vestibular system and with imaging studies using somatosensory stimulation indicated that most activation foci could be related to the vestibular component of the stimulus. Activation appeared in the region of the temporo-parietal junction, the central sulcus, and the intraparietal sulcus. These areas may be analogous to areas PIVC, 3aV, and 2v, respectively, which form in the monkey brain, the “inner vestibular circle”. Activation also occurred in premotor regions of the frontal lobe. Although undetected in previous imaging-studies using CVS, involvement of these areas could be predicted from anatomic data showing projections from the anterior ventral part of area 6 to the inner vestibular circle and the vestibular nuclei. Using a simple paradigm, we showed that GVS can be implemented safely in the fMRI environment. Manipulating stimulus waveforms and thus the GVS-induced subjective vestibular sensations in future imaging studies may yield further insights into the cortical processing of vestibular signals.


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