scholarly journals The influence of scopolamine on motor control and attentional processes

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2008 ◽  
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).

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

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.

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

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.

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

2018 ◽  
Vol 8 (11) ◽  
pp. 191 ◽  
Author(s):  
Osamu Aoki ◽  
Yoshitaka Otani ◽  
Shinichiro Morishita
Keyword(s):  
Healthy Subjects ◽  
Center Of Pressure ◽  
Force Plate ◽  
Distance Effect ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Body Sway ◽  
Mean Square ◽  
Visual Condition ◽  
Object Distance

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.

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

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

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

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.

Galvanic vestibular stimulation counteracts hypergravity-induced plastic alteration of vestibulo-cardiovascular reflex in rats

2009 ◽  
Vol 107 (4) ◽  
pp. 1089-1094 ◽  
Author(s):  
Chikara Abe ◽  
Kunihiko Tanaka ◽  
Chihiro Awazu ◽  
Hironobu Morita
Keyword(s):  
Vestibular System ◽  
Vestibular Nucleus ◽  
Pressor Response ◽  
Linear Acceleration ◽  
Vestibular Stimulation ◽  
Vertical Movement ◽  
Galvanic Vestibular Stimulation ◽  
Medial Vestibular Nucleus ◽  
Vertical Movements ◽  
Cardiovascular Reflex

Recent data from our laboratory demonstrated that, when rats are raised in a hypergravity environment, the sensitivity of the vestibulo-cardiovascular reflex decreases. In a hypergravity environment, static input to the vestibular system is increased; however, because of decreased daily activity, phasic input to the vestibular system may decrease. This decrease may induce use-dependent plasticity of the vestibulo-cardiovascular reflex. Accordingly, we hypothesized that galvanic vestibular stimulation (GVS) may compensate the decrease in phasic input to the vestibular system, thereby preserving the vestibulo-cardiovascular reflex. To examine this hypothesis, we measured horizontal and vertical movements of rats under 1-G or 3-G environments as an index of the phasic input to the vestibular system. We then raised rats in a 3-G environment with or without GVS for 6 days and measured the pressor response to linear acceleration to examine the sensitivity of the vestibulo-cardiovascular reflex. The horizontal and vertical movement of 3-G rats was significantly less than that of 1-G rats. The pressor response to forward acceleration was also significantly lower in 3-G rats (23 ± 1 mmHg in 1-G rats vs. 12 ± 1 mmHg in 3-G rats). The pressor response was preserved in 3-G rats with GVS (20 ± 1 mmHg). GVS stimulated Fos expression in the medial vestibular nucleus. These results suggest that GVS stimulated vestibular primary neurons and prevent hypergravity-induced decrease in sensitivity of the vestibulo-cardiovascular reflex.

Effect of noisy galvanic vestibular stimulation on center of pressure sway of static standing posture

2018 ◽  
Vol 11 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Yasuto Inukai ◽  
Naofumi Otsuru ◽  
Mitsuhiro Masaki ◽  
Kei Saito ◽  
Shota Miyaguchi ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Standing Posture

scholarly journals Galvanic vestibular stimulation with low intensity improves dynamic balance

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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