Effect of Eye-Object Distance on Body Sway during Galvanic Vestibular Stimulation

Gazing at objects at a near distance (small eye-object distance) can reduce body sway. However, whether body sway is regulated by movement in the mediolateral or anteroposterior direction remains unclear. Galvanic vestibular stimulation (GVS) can induce body tilting in the mediolateral or anteroposterior direction. This study examined the directionality of the eye-object distance effect, using body-tilting GVS manipulations. Ten healthy subjects (aged 21.1 ± 0.3 years) stood on a force plate covered with a piece of foamed rubber and either closed their eyes or gazed at a marker located 0.5 m, 1.0 m, or 1.5 m in front of them. The GVS polarities were set to evoke rightward, forward, and backward body tilts. To compare the effects of eye-object distance in the mediolateral and anteroposterior directions, the root mean square (RMS) of the center of pressure (COP) without GVS was subtracted from the COP RMS during GVS. For swaying in the mediolateral direction, significant visual condition-related differences were found during rightward and forward GVS (p < 0.05). Thus, reductions in mediolateral body sway are more evident for smaller eye-object distances during rightward GVS. It would be appropriate to use body-tilting GVS to detect the directionality of the eye-object distance effect.

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The Effects of Stochastic Galvanic Vestibular Stimulation on Body Sway and Muscle Activity

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2020.591671 ◽

2020 ◽

Vol 14 ◽

Author(s):

Akiyoshi Matsugi ◽

Kosuke Oku ◽

Nobuhiko Mori

Keyword(s):

Soleus Muscle ◽

Muscle Activity ◽

Center Of Pressure ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

The Body ◽

Lower Limbs ◽

Body Sway ◽

Eyes Open ◽

Significant Increment

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.

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Galvanic vestibular stimulation with low intensity improves dynamic balance

Translational Neuroscience ◽

10.1515/tnsci-2020-0197 ◽

2021 ◽

Vol 12 (1) ◽

pp. 512-521

Author(s):

Hongmei Chen ◽

Zhen Hu ◽

Yujuan Chai ◽

Enxiang Tao ◽

Kai Chen ◽

...

Keyword(s):

Healthy Subjects ◽

Center Of Pressure ◽

Balance Control ◽

Dynamic Balance ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Balance Performance ◽

Improvement Rate ◽

Average Speed ◽

Low Intensity

Abstract Background Dynamic balance is associated with fall risk. The aim of this study is to explore the effects of galvanic vestibular stimulation with very low intensity direct current (dcGVS) on dynamic balance. Methodology We used a rocker force platform for assessing the dynamic balance performance. Center-of-pressure (COP) coordinates were acquired and decomposed to rambling (RA) and trembling (TR). We measured sway parameters, including length, average speed, and average range, affected by dcGVS at 0.01 mA with eyes open (EO) and eyes closed (EC). Results We assessed 33 young healthy subjects and found that all sway parameters were shorter in the EO condition, indicating a better dynamic balance performance. dcGVS significantly improved the dynamic balance performance both in EO and EC conditions. All the sway parameters in COP in EO were significantly shorter than those in EC, indicating a better dynamic balance performance in EO. In EO, RA had greater improvement rates than TR. In EC, only average speed had a greater improvement rate in RA, whereas length and average range had greater improvement rates in TR. These results indicate a different modulation model between EO and EC. Conclusion These findings indicate that very low intensity dcGVS improved the sway parameters of dynamic balance in young healthy subjects. Moreover, our results suggest different dynamic balance control models between having EO and EC. The mechanisms of these phenomena caused by very low intensity dcGVS require further investigation.

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Noisy Galvanic Vestibular Stimulation (Stochastic Resonance) Changes Electroencephalography Activities and Postural Control in Patients with Bilateral Vestibular Hypofunction

Brain Sciences ◽

10.3390/brainsci10100740 ◽

2020 ◽

Vol 10 (10) ◽

pp. 740

Author(s):

Li-Wei Ko ◽

Rupesh Kumar Chikara ◽

Po-Yin Chen ◽

Ying-Chun Jheng ◽

Chien-Chih Wang ◽

...

Keyword(s):

Postural Control ◽

Healthy Subjects ◽

Parietal Lobe ◽

Center Of Pressure ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Precentral Gyrus ◽

Neural Activities ◽

Vestibular Hypofunction ◽

Bilateral Vestibular Hypofunction

Patients with bilateral vestibular hypofunction (BVH) often suffer from imbalance, gait problems, and oscillopsia. Noisy galvanic vestibular stimulation (GVS), a technique that non-invasively stimulates the vestibular afferents, has been shown to enhance postural and walking stability. However, no study has investigated how it affects stability and neural activities while standing and walking with a 2 Hz head yaw turning. Herein, we investigated this issue by comparing differences in neural activities during standing and walking with a 2 Hz head turning, before and after noisy GVS. We applied zero-mean gaussian white noise signal stimulations in the mastoid processes of 10 healthy individuals and seven patients with BVH, and simultaneously recorded electroencephalography (EEG) signals with 32 channels. We analyzed the root mean square (RMS) of the center of pressure (COP) sway during 30 s of standing, utilizing AMTI force plates (Advanced Mechanical Technology Inc., Watertown, MA, USA). Head rotation quality when walking with a 2 Hz head yaw, with and without GVS, was analyzed using a VICON system (Vicon Motion Systems Ltd., Oxford, UK) to evaluate GVS effects on static and dynamic postural control. The RMS of COP sway was significantly reduced during GVS while standing, for both patients and healthy subjects. During walking, 2 Hz head yaw movements was significantly improved by noisy GVS in both groups. Accordingly, the EEG power of theta, alpha, beta, and gamma bands significantly increased in the left parietal lobe after noisy GVS during walking and standing in both groups. GVS post-stimulation effect changed EEG activities in the left and right precentral gyrus, and the right parietal lobe. After stimulation, EEG activity changes were greater in healthy subjects than in patients. Our findings reveal noisy GVS as a non-invasive therapeutic alternative to improve postural stability in patients with BVH. This novel approach provides insight to clinicians and researchers on brain activities during noisy GVS in standing and walking conditions in both healthy and BVH patients.

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The effects of stochastic monopolar galvanic vestibular stimulation on human postural sway

Journal of Vestibular Research ◽

10.3233/ves-2003-122-303 ◽

2003 ◽

Vol 12 (2-3) ◽

pp. 77-85

Author(s):

Anthony P. Scinicariello ◽

J. Timothy Inglis ◽

J.J. Collins

Keyword(s):

Vestibular System ◽

Postural Sway ◽

Center Of Pressure ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Lower Sensitivity ◽

Input Stimulus ◽

Vestibular Perception ◽

Afferent Nerve Endings ◽

Young Subjects

Galvanic vestibular stimulation (GVS) is a technique in which small currents are delivered transcutaneously to the afferent nerve endings of the vestibular system through electrodes placed over the mastoid bones. The applied current alters the firing rates of the peripheral vestibular afferents, causing a shift in a standing subject's vestibular perception and a corresponding postural sway. Previously, we showed that in subjects who are facing forward, stochastic bipolar binaural GVS leads to coherent stochastic mediolateral postural sway. The goal of this pilot study was to extend that work and to test the hypothesis that in subjects who are facing forward, stochastic monopolar binaural GVS leads to coherent stochastic anteroposterior postural sway. Stochastic monopolar binaural GVS was applied to ten healthy young subjects. Twenty-four trials, each containing a different galvanic input stimulus from among eight different frequency ranges, were conducted on each subject. Postural sway was evaluated through analysis of the center-of-pressure (COP) displacements under each subject's feet. Spectral analysis was performed on the galvanic stimuli and the COP displacement time series to calculate the coherence spectra. Significant coherence was found between the galvanic input signal and the anteroposterior COP displacement in some of the trials (i.e., at least one) in nine of the ten subjects. In general, the coherence values were highest for the mid-range frequencies that were tested, and lowest for the low- and high-range frequencies. However, the coherence values we obtained were lower than those we previously reported for stochastic bipolar binaural GVS and mediolateral sway. These differences may be due to fundamental characteristics of the vestibular system such as lower sensitivity to symmetric changes in afferent firing dynamics, and/or differences between the biomechanics of anteroposterior and mediolateral sway.

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Assessing head acceleration to identify a motor threshold to galvanic vestibular stimulation

Journal of Neurophysiology ◽

10.1152/jn.00254.2020 ◽

2021 ◽

Author(s):

Youstina Mikhail ◽

Jonathan Charron ◽

Jean-Marc Mac Thiong ◽

Dorothy Barthélemy

Keyword(s):

Center Of Pressure ◽

Vestibular Function ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Head Acceleration ◽

Motor Threshold ◽

Recruitment Curve ◽

Eyes Closed ◽

Postural Responses ◽

Significant Difference

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.

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Differences in Balance Function Between Cancer Survivors and Healthy Subjects: A Pilot Study

Integrative Cancer Therapies ◽

10.1177/1534735418790387 ◽

2018 ◽

Vol 17 (4) ◽

pp. 1144-1149 ◽

Cited By ~ 6

Author(s):

Shinichiro Morishita ◽

Yuta Mitobe ◽

Atsuhiro Tsubaki ◽

Osamu Aoki ◽

Jack B. Fu ◽

...

Keyword(s):

Muscle Strength ◽

Cancer Survivors ◽

Healthy Subjects ◽

Center Of Pressure ◽

Healthy Adults ◽

Body Sway ◽

Balance Function ◽

Adult Cancer Survivors ◽

Eyes Open ◽

The Mean

Older adults who have survived cancer experience significantly more falls compared with healthy adults. Adult cancer survivors may also have a lower balance function than healthy adults. We examined muscle strength and balance function among 19 cancer survivors and 14 healthy subjects. The mean age of the cancer survivors was 51.5 ± 11.2 years; 6 men and 13 women. Cancer diagnoses included breast cancer, retroperitoneal sarcoma, acute leukemia, lung cancer, colorectal cancer, thyroid cancer, Ewing’s sarcoma, and tongue cancer. The mean age of healthy subjects was 47.4 ± 14 years; 3 men, 11 women. Muscle strength was assessed using hand grip and knee extensor strength tests. Balance function was evaluated using the Timed Up and Go (TUG) test, and body sway was tested using a force platform. No significant differences were found with respect to right and left grip strength or right and left knee extension strength between the 2 groups. A significantly higher TUG time was observed in cancer survivors than in healthy subjects ( P < .05). With eyes open, the area of the center of pressure was significantly larger in cancer survivors than in healthy subjects ( P < .05). Similarly, the length per area was significantly lower both with eyes open and closed for cancer survivors than for healthy subjects ( P < .05). TUG was significantly correlated with muscle strength in both groups ( P < .05). However, no body sway parameters were related to muscle strength in either group. Cancer survivors had lower balance function that might not have been related to muscle strength. Cancer survivors should be evaluated for balance function as there is a potential for impairment. The findings of this study will be relevant for planning the prevention of falls for cancer survivors.

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Noisy galvanic vestibular stimulation effect on center of pressure sway during one-legged standing

Journal of Clinical Neuroscience ◽

10.1016/j.jocn.2020.10.050 ◽

2020 ◽

Vol 82 ◽

pp. 173-178

Author(s):

Yasuto Inukai ◽

Shota Miyaguchi ◽

Natsuki Kobayashi ◽

Naofumi Otsuru ◽

Hideaki Onishi

Keyword(s):

Center Of Pressure ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation

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Head motion predictability explains activity-dependent suppression of vestibular balance control

10.1101/560664 ◽

2019 ◽

Author(s):

H Dietrich ◽

F Heidger ◽

R Schniepp ◽

PR MacNeilage ◽

S Glasauer ◽

...

Keyword(s):

Center Of Pressure ◽

Balance Control ◽

Vestibular Stimulation ◽

Head Movements ◽

Body Sway ◽

Cycle Phase ◽

Feed Forward ◽

Time Frequency ◽

Self Motion ◽

Activity Dependent

AbstractVestibular balance control is dynamically weighted during locomotion. This might result from a selective suppression of vestibular inputs in favor of a feed-forward balance regulation based on locomotor efference copies. The feasibility of such a feed-forward mechanism should however critically depend on the predictability of head movements (PHM) during locomotion. To test this, we studied in healthy subjects the differential impact of a stochastic vestibular stimulation (SVS) on body sway (center-of-pressure, COP) during standing and walking at different speeds using time-frequency analyses and compared it to activity-dependent changes in PHM. SVS-COP coupling decreased from standing to walking and further dropped with faster locomotion. Correspondingly, PHM increased with faster locomotion. Furthermore, SVS-COP coupling depended on the gait-cycle-phase with peaks corresponding to periods of least PHM. These findings support the assumption that during stereotyped human self-motion, locomotor efference copies selectively replace vestibular cues, similar to what was previously observed in animal models.

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The influence of scopolamine on motor control and attentional processes

PeerJ ◽

10.7717/peerj.2008 ◽

2016 ◽

Vol 4 ◽

pp. e2008 ◽

Cited By ~ 3

Author(s):

Emma Bestaven ◽

Charline Kambrun ◽

Dominique Guehl ◽

Jean-René Cazalets ◽

Etienne Guillaud

Keyword(s):

Motor Control ◽

Motion Sickness ◽

Center Of Pressure ◽

Vestibular Nucleus ◽

Parabolic Flight ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

Balance Test ◽

Attentional Processes ◽

Perception Of Verticality

Background:Motion sickness may be caused by a sensory conflict between the visual and the vestibular systems. Scopolamine, known to be the most effective therapy to control the vegetative symptoms of motion sickness, acts on the vestibular nucleus and potentially the vestibulospinal pathway, which may affect balance and motor tasks requiring both attentional process and motor balance. The aim of this study was to explore the effect of scopolamine on motor control and attentional processes.Methods:Seven subjects were evaluated on four different tasks before and after a subcutaneous injection of scopolamine (0.2 mg): a one-minute balance test, a subjective visual vertical test, a pointing task and a galvanic vestibular stimulation with EMG recordings.Results:The results showed that the reaction time and the movement duration were not modified after the injection of scopolamine. However, there was an increase in the center of pressure displacement during the balance test, a decrease in EMG muscle response after galvanic vestibular stimulation and an alteration in the perception of verticality.Discussion:These results confirm that low doses of scopolamine such as those prescribed to avoid motion sickness have no effect on attentional processes, but that it is essential to consider the responsiveness of each subject. However, scopolamine did affect postural control and the perception of verticality. In conclusion, the use of scopolamine to prevent motion sickness must be considered carefully because it could increase imbalances in situations when individuals are already at risk of falling (e.g., sailing, parabolic flight).

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Comparison of verticality perception and postural sway induced by double temple-mastoidal and bipolar binaural 20 Hz sinusoidal galvanic vestibular stimulation

Journal of Vestibular Research ◽

10.3233/ves-210112 ◽

2021 ◽

pp. 1-15

Author(s):

Samar Babaee ◽

Moslem Shaabani ◽

Mohsen Vahedi

Keyword(s):

Postural Sway ◽

Maximum Amplitude ◽

Semicircular Canals ◽

Vestibular Stimulation ◽

Galvanic Vestibular Stimulation ◽

The Body ◽

Body Sway ◽

Mean Values ◽

Amplitude Change ◽

Threshold Levels

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.

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