scholarly journals Strategic alterations of posture are delayed in Parkinson’s disease patients during deep brain stimulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mitesh Patel ◽  
Maria H. Nilsson ◽  
Stig Rehncrona ◽  
Fredrik Tjernström ◽  
Måns Magnusson ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
The Body ◽  
Linear Motion ◽  
Quiet Stance ◽  
Vibration Period ◽  
Ankle Strategy ◽  
Eyes Closed ◽  
Eyes Open ◽  
S Period ◽  
Deep Brain

AbstractParkinson’s disease (PD) is characterized by rigidity, akinesia, postural instability and tremor. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces tremor but the effects on postural instability are inconsistent. Another component of postural control is the postural strategy, traditionally referred to as the ankle or hip strategy, which is determined by the coupling between the joint motions of the body. We aimed to determine whether DBS STN and vision (eyes open vs. eyes closed) affect the postural strategy in PD in quiet stance or during balance perturbations. Linear motion was recorded from the knee, hip, shoulder and head in 10 patients with idiopathic PD with DBS STN (after withdrawal of other anti-PD medication), 25 younger adult controls and 17 older adult controls. Correlation analyses were performed on anterior–posterior linear motion data to determine the coupling between the four positions measured. All participants were asked to stand for a 30 s period of quiet stance and a 200 s period of calf vibration. The 200 s vibration period was subdivided into four 50 s periods to study adaptation between the first vibration period (30–80 s) and the last vibration period (180–230 s). Movement was recorded in patients with PD with DBS ON and DBS OFF, and all participants were investigated with eyes closed and eyes open. DBS settings were randomized and double-blindly programmed. Patients with PD had greater coupling of the body compared to old and young controls during balance perturbations (p ≤ 0.046). Controls adopted a strategy with greater flexibility, particularly using the knee as a point of pivot, whereas patients with PD adopted an ankle strategy, i.e., they used the ankle as the point of pivot. There was higher flexibility in patients with PD with DBS ON and eyes open compared to DBS OFF and eyes closed (p ≤ 0.011). During balance perturbations, controls quickly adopted a new strategy that they retained throughout the test, but patients with PD were slower to adapt. Patients with PD further increased the coupling between segmental movement during balance perturbations with DBS ON but retained a high level of coupling with DBS OFF throughout balance perturbations. The ankle strategy during balance perturbations in patients with PD was most evident with DBS OFF and eyes closed. The increased coupling with balance perturbations implies a mechanism to reduce complexity at a cost of exerting more energy. Strategic alterations of posture were altered by DBS in patients with PD and were delayed. Our findings therefore show that DBS does not fully compensate for disease-related effects on posture.

Effectiveness of Deep Brain Stimulation in Reducing Body Mass Index and Weight: A Systematic Review

2021 ◽  
pp. 1-11
Author(s):  
William Omar Contreras López ◽  
Paula Alejandra Navarro ◽  
Santiago Crispín
Keyword(s):  
Systematic Review ◽  
Body Mass Index ◽  
Deep Brain Stimulation ◽  
Body Mass ◽  
Brain Stimulation ◽  
The Body ◽  
Health Concern ◽  
Prader Willi Syndrome ◽  
Falling Asleep ◽  
Deep Brain

<b><i>Background:</i></b> Obesity has become a major public health concern worldwide, with current behavioral, pharmacological, and surgical treatments offering varying rates of success and adverse effects. Neurosurgical approaches to treatment of refractory obesity include deep brain stimulation (DBS) on either specific hypothalamic or reward circuitry nuclei, which might contribute to weight reduction through different mechanisms. We aimed to determine the safety and clinical effect of DBS in medical refractory obesity. <b><i>Summary:</i></b> Adhering to PRISMA guidelines, we performed a systematic review to identify all original studies – observational and experimental – in which DBS was performed to treat refractory obesity. From database inception to April 2021, we conducted our search in PubMed, Scopus, and LILACS databases using the following MeSH terms: “Obesity” OR “Prader-Willi Syndrome” AND “Deep Brain Stimulation.” The main outcomes were safety and weight loss measured with the body mass index (BMI). The Grading of Recommendations Assessment, Development, and Evaluation methods were applied to evaluate the quality of evidence. This study protocol was registered with PROSPERO ID: CRD42019132929. Seven studies involving 12 patients met the inclusion criteria; the DBS target was the nucleus accumbens in four (57.1%), the lateral hypothalamic area in two (29.6%), and the ventral hypothalamus in one (14.3%). Further, 33% of participants had obesity secondary to Prader-Willi syndrome (PWS) and 66.6% had primary obesity. The global BMI average at baseline was 46.7 (SD: 9.6, range: 32.2–59.1), and after DBS, 42.8 (SD: 8.8, range: 25–53.9), with a mean difference of 3.9; however, the delta in PWS patients was −2.3 and 10 in those with primary obesity. The incidence of moderate side effects was 33% and included manic symptoms (<i>N</i> = 2), electrode fracture (<i>N</i> = 1), and seizure (<i>N</i> = 1); mild complications (41.6%) included skin infection (<i>N</i> = 2), difficulties falling asleep (<i>N</i> = 1), nausea (<i>N</i> = 1), and anxiety (<i>N</i> = 1). <b><i>Key Messages:</i></b> Despite available small case series and case reports reporting a benefit in the treatment of refractory obesity with DBS, this study emphasizes the need for prospective studies with longer follow-ups in order to further address the efficacy and indications.

scholarly journals Reconfigurable MRI coil technology can substantially reduce RF heating at the tips of bilateral deep brain stimulation implants

2018 ◽  
Author(s):  
Laleh Golestanirad ◽  
Boris Keil ◽  
Sean Downs ◽  
John Kirsch ◽  
Behzad Elahi ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Temperature Rise ◽  
Substantial Reduction ◽  
The Body ◽  
Rf Heating ◽  
Coil System ◽  
Body Coil ◽  
Magnetic Resonance Imaging Mri ◽  
Deep Brain

AbstractPatients with deep brain stimulation (DBS) implants can significantly benefit from magnetic resonance imaging (MRI) examination, however, access to MRI is restricted in this patients because of safety concerns due to RF heating of the leads. Recently we introduced a patient-adjustable reconfigurable MRI coil system to reduce the SAR at the tip of deep brain stimulation implants during MRI at 1.5T. A simulation study with realistic models of single (unilateral) DBS leads demonstrated a substantial reduction in the local SAR up to 500-fold could be achieved using the coil system compared to quadrature birdcage coils. Many patients however, have bilateral DBS implants and the question arises whether the rotating coil system can be used in for them. This work reports the results of phantom experiments measuring the temperature rise at the tips of bilateral DBS implants with realistic trajectories extracted from postoperative CT images of 10 patients (20 leads in total). A total of 200 measurements were performed to record temperature rise at the tips of the leads during 2 minutes of scanning with the coil rotated to cover all accessible rotation angles. In all patients, we were able to find an optimum coil rotation angle and reduced the heating of both left and right leads to a level below the heating produced by the body coil. An average heat reduction of 65% was achieved for bilateral leads. Reconfigurable coil technology introduces a promising approach for imaging of patients with DBS implants.

scholarly journals The Ability of Gymnastics Motoric Perceptual Based on Local Culture for Early Childhood in Aceh Province

2020 ◽  
Vol 3 (2) ◽  
pp. 749-762
Author(s):  
Muhammad Riski Kurniawan ◽  
Syamsulrizal Syamsulrizal ◽  
Razali Razali ◽  
Israwati Israwati
Keyword(s):  
Early Childhood ◽  
The Body ◽  
Local Culture ◽  
Homogeneity Test ◽  
Tennis Ball ◽  
Eyes Closed ◽  
Aceh Province ◽  
Eyes Open ◽  
Perceptual Ability ◽  
The Impact

Local culture-based gymnastics is a combination of Seudati dance with Saman dances movements as well as cheerful healthy exercises that are already in kindergarten. The purpose of this study was to determine the impact of the implementation of local culture-based exercise on the motorized perceptual ability of early childhood in Banda Aceh Kindergarten. This study uses a quantitative approach to the type of experimental research. Population and a sample of 30 students were selected by purposive sampling. Data collection techniques of motoric perceptual ability using tests: (1) Standing on the beam while touching the limbs as instructed by the teacher with eyes open, (2 ) Standing on the beam while touching the body as instructed by the teacher with eyes closed, (3) Jumping and landing in a line with two feet pressed together as instructed by the teacher with eyes open, (4) Jumping and landing in a line with two feet pressed together as instructed by the teacher with eyes closed , (5) Walking in balance, (6) Throwing a tennis ball into a basket with a distance of 2 meters. Before the data is analyzed, the research data is tested for the analysis requirements, namely the normality and homogeneity test. Then the data is analyzed using the t-test. Based on the results of data analysis obtained t count (18.455)> t table (2.045), thus it can be concluded that there is a significant influence between local culture-based exercise on the motoric perceptual ability of early childhood in Aceh kindergarten.      

scholarly journals Exploring the effects of deep brain stimulation and vision on tremor in Parkinson’s disease - benefits from objective methods

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Per-Anders Fransson ◽  
Maria H. Nilsson ◽  
Diederick C. Niehorster ◽  
Marcus Nyström ◽  
Stig Rehncrona ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Deep Brain Stimulation ◽  
Motion Capture ◽  
Brain Stimulation ◽  
The Body ◽  
Motion Capture System ◽  
3D Motion ◽  
3D Motion Capture ◽  
Deep Brain

Abstract Background Tremor is a cardinal symptom of Parkinson’s disease (PD) that may cause severe disability. As such, objective methods to determine the exact characteristics of the tremor may improve the evaluation of therapy. This methodology study aims to validate the utility of two objective technical methods of recording Parkinsonian tremor and evaluate their ability to determine the effects of Deep Brain Stimulation (DBS) of the subthalamic nucleus and of vision. Methods We studied 10 patients with idiopathic PD, who were responsive to L-Dopa and had more than 1 year use of bilateral subthalamic nucleus stimulation. The patients did not have to display visible tremor to be included in the study. Tremor was recorded with two objective methods, a force platform and a 3 dimensional (3D) motion capture system that tracked movements in four key proximal sections of the body (knee, hip, shoulder and head). They were assessed after an overnight withdrawal of anti-PD medications with DBS ON and OFF and with eyes open and closed during unperturbed and perturbed stance with randomized calf vibration, using a randomized test order design. Results Tremor was detected with the Unified Parkinson’s Disease Rating Scale (UPDRS) in 6 of 10 patients but only distally (hands and feet) with DBS OFF. With the force platform and the 3D motion capture system, tremor was detected in 6 of 10 and 7 of 10 patients respectively, mostly in DBS OFF but also with DBS ON in some patients. The 3D motion capture system revealed that more than one body section was usually affected by tremor and that the tremor amplitude was non-uniform, but the frequency almost identical, across sites. DBS reduced tremor amplitude non-uniformly across the body. Visual input mostly reduced tremor amplitude with DBS ON. Conclusions Technical recording methods offer objective and sensitive detection of tremor that provide detailed characteristics such as peak amplitude, frequency and distribution pattern, and thus, provide information that can guide the optimization of treatments. Both methods detected the effects of DBS and visual input but the 3D motion system was more versatile in that it could detail the presence and properties of tremor at individual body sections.

Stiffness Control of Balance in Quiet Standing

1998 ◽  
Vol 80 (3) ◽  
pp. 1211-1221 ◽  
Author(s):  
David A. Winter ◽  
Aftab E. Patla ◽  
Francois Prince ◽  
Milad Ishac ◽  
Krystyna Gielo-Perczak
Keyword(s):  
The Body ◽  
Quiet Standing ◽  
Error Signal ◽  
Reactive Control ◽  
Eyes Closed ◽  
Stiffness Model ◽  
Significant Difference ◽  
Eyes Open ◽  
Stiffness Control ◽  
Corrective Response

Winter, David A., Aftab E. Patla, Francois Prince, Milad Ishac, and Krystyna Gielo-Perczak. Stiffness control of balance in quiet standing. J. Neurophysiol. 80: 1211–1221, 1998. Our goal was to provide some insights into how the CNS controls and maintains an upright standing posture, which is an integral part of activities of daily living. Although researchers have used simple performance measures of maintenance of this posture quite effectively in clinical decision making, the mechanisms and control principles involved have not been clear. We propose a relatively simple control scheme for regulation of upright posture that provides almost instantaneous corrective response and reduces the operating demands on the CNS. The analytic model is derived and experimentally validated. A stiffness model was developed for quiet standing. The model assumes that muscles act as springs to cause the center-of-pressure (COP) to move in phase with the center-of-mass (COM) as the body sways about some desired position. In the sagittal plane this stiffness control exists at the ankle plantarflexors, in the frontal plane by the hip abductors/adductors. On the basis of observations that the COP-COM error signal continuously oscillates, it is evident that the inverted pendulum model is severely underdamped, approaching the undamped condition. The spectrum of this error signal is seen to match that of a tuned mass, spring, damper system, and a curve fit of this “tuned circuit” yields ωn the undamped natural frequency of the system. The effective stiffness of the system, K e , is then estimated from K e = Iω2 n, and the damping B is estimated from B = BW × I, where BW is the bandwidth of the tuned response (in rad/s), and I is the moment of inertia of the body about the ankle joint. Ten adult subjects were assessed while standing quietly at three stance widths: 50% hip-to-hip distance, 100 and 150%. Subjects stood for 2 min in each position with eyes open; the 100% stance width was repeated with eyes closed. In all trials and in both planes, the COP oscillated virtually in phase (within 6 ms) with COM, which was predicted by a simple 0th order spring model. Sway amplitude decreased as stance width increased, and K e increased with stance width. A stiffness model would predict sway to vary as K −0.5 e . The experimental results were close to this prediction: sway was proportional to K −0.55 e . Reactive control of balance was not evident for several reasons. The visual system does not appear to contribute because no significant difference between eyes open and eyes closed results was found at 100% stance width. Vestibular (otolith) and joint proprioceptive reactive control were discounted because the necessary head accelerations, joint displacements, and velocities were well below reported thresholds. Besides, any reactive control would predict that COP would considerably lag (150–250 ms) behind the COM. Because the average COP was only 4 ms delayed behind the COM, reactive control was not evident; this small delay was accounted for by the damping in the tuned mechanical system.

scholarly journals Postural Balance Ability and the Effect of Visual Restriction on Older Dancers and Non-Dancers

2021 ◽  
Vol 3 ◽  
Author(s):  
Maria-Elissavet Nikolaidou ◽  
Vasilios Karfis ◽  
Maria Koutsouba ◽  
Arno Schroll ◽  
Adamantios Arampatzis
Keyword(s):  
Repeated Measures ◽  
Postural Balance ◽  
Path Length ◽  
Performance Test ◽  
Control Group ◽  
Quiet Stance ◽  
Balance Performance ◽  
Visual Channel ◽  
Eyes Closed ◽  
Eyes Open

Dance has been suggested to be an advantageous exercise modality for improving postural balance performance and reducing the risk of falls in the older population. The main purpose of this study was to investigate whether visual restriction impacts older dancers and non-dancers differently during a quiet stance balance performance test. We hypothesized higher balance performance and greater balance deterioration due to visual restriction in dancers compared with non-dancers, indicating the superior contribution of the visual channel in the expected higher balance performances of dancers. Sixty-nine (38 men, 31 women, 74 ± 6 years) healthy older adults participated and were grouped into a Greek traditional dance group (n = 31, two to three times/week for 1.5 h/session, minimum of 3 years) and a non-dancer control group (n = 38, no systematic exercise history). The participants completed an assessment of one-legged quiet stance trials using both left and right legs and with eyes open while standing barefoot on a force plate (Wii, A/D converter, 1,000 Hz; Biovision) and two-legged trials with both eyes open and closed. The possible differences in the anthropometric and one-legged balance parameters were examined by a univariate ANOVA with group and sex as fixed factors. This ANOVA was performed using the same fixed factors and vision as the repeated measures factor for the two-legged balance parameters. In the one-legged task, the dance group showed significantly lower values in anteroposterior and mediolateral sway amplitudes (p = 0.001 and p = 0.035) and path length measured in both directions (p = 0.001) compared with the non-dancers. In the two-legged stance, we found a significant vision effect on path length (p &lt; 0.001) and anteroposterior amplitude (p &lt; 0.001), whereas mediolateral amplitude did not differ significantly (p = 0.439) between closed and open eyes. The dance group had a significantly lower CoP path length (p = 0.006) and anteroposterior (p = 0.001) and mediolateral sway amplitudes (p = 0.003) both in the eyes-open and eyes-closed trials compared with the control group. The superior balance performance in the two postural tasks found in the dancers is possibly the result of the coordinated, aesthetically oriented intersegmental movements, including alternations between one- and two-legged stance phases, that comes with dance. Visual restriction resulted in a similar deterioration of balance performance in both groups, thus suggesting that the contribution of the visual channel alone cannot explain the superior balance performance of dancers.

scholarly journals Postural control in girls with adolescent idiopathic scoliosis while wearing a Chêneau brace or performing active self-correction: a pilot study

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7513 ◽  
Author(s):  
Elżbieta Piątek ◽  
Michał Kuczyński ◽  
Bożena Ostrowska
Keyword(s):  
Fractal Dimension ◽  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Postural Control ◽  
Reciprocal Relationship ◽  
Quiet Standing ◽  
Quiet Stance ◽  
Therapeutic Modalities ◽  
Eyes Closed ◽  
Eyes Open

Background It is known that adolescent idiopathic scoliosis (AIS) is often accompanied by balance deficits. This reciprocal relationship must be taken into account when prescribing new therapeutic modalities because these may differently affect postural control, interacting with therapy and influencing its results. Objective The purpose was to compare postural control in girls with AIS while wearing the Chêneau brace (BRA) or performing active self-correction (ASC) with their postural control in a quiet comfortable stance. Methods Nine subjects were evaluated on a force plate in three series of two 20-s quiet standing trials with eyes open or closed; three blocks were randomly arranged: normal quiet stance (QST), quiet stance with BRA, and quiet stance with ASC. On the basis of centre-of-pressure (COP) recordings, the spatial and temporal COP parameters were computed. Results and Discussion Performing ASC was associated with a significant backward excursion of the COP mean position with eyes open and closed (ES = 0.56 and 0.65, respectively; p < 0.05). This excursion was accompanied by an increase in the COP fractal dimension (ES = 1.05 and 0.98; p < 0.05) and frequency (ES = 0.78; p = 0.10 and ES = 1.14; p < 0.05) in the mediolateral (ML) plane. Finally, both therapeutic modalities decreased COP sample entropy with eyes closed in the anteroposterior (AP) plane. Wearing BRA resulted in ES = 1.45 (p < 0.05) while performing ASC in ES = 0.76 (p = 0.13). Conclusion The observed changes in the fractal dimension (complexity) and frequency caused by ASC account for better adaptability of patients to environmental demands and for their adequate resources of available postural strategies in the ML plane. These changes in sway structure were accompanied by a significant (around 25 mm) backward excursion of the mean COP position. However, this improvement was achieved at the cost of lower automaticity, i.e. higher attentional involvement in postural control in the AP plane. Wearing BRA may have an undesirable effect on some aspects of body balance.

A Postural Model of Balance-Correcting Movement Strategies

1992 ◽  
Vol 2 (4) ◽  
pp. 323-347
Author(s):  
J.H.J. Allum ◽  
F. Honegger
Keyword(s):  
Normal Subjects ◽  
Opposite Polarity ◽  
The Body ◽  
Joint Torque ◽  
Support Surface ◽  
Joint Torques ◽  
Eyes Closed ◽  
Movement Strategies ◽  
Eyes Open ◽  
Balance Corrections

The patterns of joint torques and movement strategies underlying human balance corrections were examined using a postural model. Two types of support-surface perturbation, dorsiflexion rotation (ROT) and rearward translation (TRANS), were employed. These two perturbations were adjusted to produce similar profiles of ankle dorsiflexion in order to obtain information on the role of lower leg proprioceptive inputs on triggering balance corrections. In addition, the dependence of balance control on head angular and linear accelerations was investigated by comparing the responses of normal and vestibularly deficient subjects under eyes-closed and eyes-open conditions. Differences in ROT and TRANS movement strategies were examined in three ways First, the amplitude and polarity of active joint torques were analysed. These were obtained by altering joint torques applied to a postural model until movements of the model accurately duplicated those of measured responses. Second, the pattern of body-segment angular movements depicted by stick figures moving in response to the computed joint torques was investigated. Third, the peak amplitude and patterns of crosscorrelations between joint torques were measured. Active ankle, knee, and hip joint torques computed for normal subjects rotated the body forward for ROT. In the case of TRANS, computed active torques in normal were of opposite polarity to those of ROT and reversed the forward motion of the body. Subjects with vestibular deficits had lower amplitude torques for ROT and failed to counter the platform rotation. Hip torques for TRANS in vestibular deficient subjects were of opposite polarity to those of normal subjects and resulted in excessive forward trunk rotation. Normally, neck torques acted to stabilize the head in space when trunk angular velocity peaked. Vestibular deficient subjects displayed head movements in response to ROT similar to those generated when neck torques were absent. For TRANS, these same subjects exhibited overcompensatory neck torques. Stick figures of normal responses indicated a stiffening of the body into a leg and a trunk-head link for ROT and a flexible multilink motion for TRANS. Likewise, normal response strategies, defined by using crosscorrelations of joint torques, differed for ROT and TRANS. All joint torque crosscorrelations were significant for TRANS. Neck torques led those of all other joint torques by 40 ms or more, and hip joint led ankle torques by 30 ms. Joint torque correlations for ROT were organised around hip and ankle torques without a major correlation to neck torques. Fundamental changes in all torque crosscorrelations occurred for vestibularly deficient subjects under both eyes-open and eyes-closed conditions. These results support the hypothesis that the modulation of postural responses by vestibular signals occurs at all major joint links of the upright human body and that the strategy underlying balance corrections at the hip and neck is selected independent of local sensory input from the lower leg. Rearward translation and dorsiflexion rotation of a support-surface elicit different movement strategies when ankle angle, changes are matched for such disturbances to human upright balance.

scholarly journals Magnetothermal genetic deep brain stimulation of motor behaviors in awake, freely moving mice

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Rahul Munshi ◽  
Shahnaz M Qadri ◽  
Qian Zhang ◽  
Idoia Castellanos Rubio ◽  
Pablo del Pino ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Motor Behavior ◽  
Freezing Of Gait ◽  
Dorsal Striatum ◽  
Field Application ◽  
The Body ◽  
Superparamagnetic Nanoparticles ◽  
Neuronal Membrane ◽  
Deep Brain

Establishing how neurocircuit activation causes particular behaviors requires modulating the activity of specific neurons. Here, we demonstrate that magnetothermal genetic stimulation provides tetherless deep brain activation sufficient to evoke motor behavior in awake mice. The approach uses alternating magnetic fields to heat superparamagnetic nanoparticles on the neuronal membrane. Neurons, heat-sensitized by expressing TRPV1 are activated with magnetic field application. Magnetothermal genetic stimulation in the motor cortex evoked ambulation, deep brain stimulation in the striatum caused rotation around the body-axis, and stimulation near the ridge between ventral and dorsal striatum caused freezing-of-gait. The duration of the behavior correlated tightly with field application. This approach provides genetically and spatially targetable, repeatable and temporarily precise activation of deep-brain circuits without the need for surgical implantation of any device.

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
Keyword(s):  
Body Movement ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
The Body ◽  
Muscle Vibration ◽  
Quiet Stance ◽  
Foot Pressure ◽  
Galvanic Stimulation ◽  
Eyes Closed ◽  
Leg Muscle

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.

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