The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Marianne Dieterich - One of the best experts on this subject based on the ideXlab platform.
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functional mri of galvanic Vestibular Stimulation with alternating currents at different frequencies
NeuroImage, 2005Co-Authors: Thomas Stephan, Thomas Brandt, Erich Schneider, Marianne Dieterich, Angela Deutschlander, Annina Nolte, Martin WiesmannAbstract:Abstract Functional MRI was performed in 28 healthy volunteers to study the effects of galvanic Vestibular Stimulation with alternating currents (AC-GVS) of different frequencies on brain activation patterns. The aims of this study were (1) to identify specific areas within the Vestibular cortical network that are involved in the processing of frequency-specific aspects by correlation analyses, (2) to determine the optimal frequency for Stimulation of the Vestibular system with respect to perception, and (3) to analyze whether different frequencies of AC-GVS are mediated in different cortical areas or different sites within the Vestibular cortex. AC-GVS was performed using sinusoidal Stimulation currents with an amplitude of ±2.5 mA, and frequencies of 0.1 Hz, 0.3 Hz, 0.8 Hz, 1.0 Hz, 2.0 Hz, and 5.0 Hz were applied. Regardless of the applied Stimulation frequency, AC-GVS elicited activations within a network of multisensory areas similar to those described in earlier studies using direct currents. No mapping of different Stimulation frequencies to different cortical locations was observed. Additional activations of somatosensory cortex areas were observed during Stimulation with 5 Hz only. The strongest Vestibular sensations were reported during Stimulation with 1 Hz and 2 Hz. Correlation analyses between blood oxygenation level dependent (BOLD) signal changes and Stimulation frequency revealed a positive dependency in areas of the supramarginal gyrus, posterolateral thalamus, cerebellar vermis, posterior insula, and in the hippocampal region/uncus. These regions represent areas involved in the processing of Vestibular information for head and body orientation in space.
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comparison of human ocular torsion patterns during natural and galvanic Vestibular Stimulation
Journal of Neurophysiology, 2002Co-Authors: Erich Schneider, Stefan Glasauer, Marianne DieterichAbstract:Galvanic Vestibular Stimulation (GVS) is reported to induce interindividually variable tonic ocular torsion (OT) and superimposed torsional nystagmus. It has been proposed that the tonic component results from the activation of otolith afferents. We tested our hypothesis that both the tonic and the phasic OT are mainly due to semicircular canal (SCC) Stimulation by examining whether the OT patterns elicited by GVS can be reproduced by pure SCC Stimulations. Using videooculography we measured the OT of six healthy subjects while two different stimuli with a duration of 20 s were applied: 1 ) transmastoidal GVS steps of 2 mA with the head in a pitched nose-down position and 2 ) angular head rotations around a combined roll-yaw axis parallel to the gravity vector with the head in the same position. The Stimulation profile was individually scaled to match the nystagmus properties from GVS and consisted of a sustained velocity step of 4–12°/s on which a velocity ramp of 0.67–2°/s2 was superimposed. Since blinks were reported to induce transient torsional eye movements, the subjects were also asked to blink once 10 s after stimulus onset. Analysis of torsional eye movements under both conditions revealed no significant differences. Thus we conclude that both the tonic and the phasic OT responses to GVS can be reproduced by pure rotational Stimulations and that the OT-related effects of GVS on SCC afferents are similar to natural Stimulations at small amplitudes.
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comparison of human ocular torsion patterns during natural and galvanic Vestibular Stimulation
Journal of Neurophysiology, 2002Co-Authors: Erich Schneider, Stefan Glasauer, Marianne DieterichAbstract:Galvanic Vestibular Stimulation (GVS) is reported to induce interindividually variable tonic ocular torsion (OT) and superimposed torsional nystagmus. It has been proposed that the tonic component ...
Yoshiharu Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Noisy Vestibular Stimulation increases gait speed in normals and in bilateral vestibulopathy
Brain stimulation, 2018Co-Authors: Shin-ichi Iwasaki, Chisato Fujimoto, Naoya Egami, Makoto Kinoshita, Fumiharu Togo, Yoshiharu Yamamoto, Tatsuya YamasobaAbstract:Abstract Background Galvanic Vestibular Stimulation delivered as zero-mean current noise (noisy GVS) has been shown to improve static and dynamic postural stability probably by enhancing Vestibular information. Objective /Hypothesis: To examine the effect of an imperceptible level of noisy GVS on dynamic locomotion in normal subjects as well as in patients with bilateral vestibulopathy. Methods Walking performance of 19 healthy subjects and 12 patients with bilateral vestibulopathy at their preferred speed was examined during application of noisy GVS with an amplitude ranging from 0 to 1000 μA. The gait velocity, stride length and stride time were analyzed. Results Noisy GVS had significant effects on gait velocity, stride length and stride time in healthy subjects as well as in patients with bilateral vestibulopathy (p 0.4). Conclusion Noisy GVS is effective in improving gait performance in healthy subjects as well as in patients with bilateral vestibulopathy.
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Noisy Galvanic Vestibular Stimulation Sustainably Improves Posture in Bilateral Vestibulopathy
Frontiers Media S.A., 2018Co-Authors: Chisato Fujimoto, Naoya Egami, Tatsuya Yamasoba, Yoshiharu Yamamoto, Takuya Kawahara, Yukari Uemura, Shin-ichi IwasakiAbstract:Patients with bilateral vestibulopathy (BV) suffer from persistent postural imbalance, leading to a marked decrease in quality of life and a higher risk of falls. However, so far, the effective treatments for BV are very limited. We examined whether long-term noisy galvanic Vestibular Stimulation (nGVS) keeps improving body balance after the cessation of the stimulus in BV patients. Thirteen BV patients received nGVS for 30 min with a lower intensity than the intensity at which they feel any cutaneous sensations, and their postural movement was monitored for 6 h after the stimuli. The same session was repeated at 14-day intervals. Stance tasks on two legs were performed with eyes closed. The velocity of the center of pressure (COP) movement, the area enclosed by the COP movement, and the root mean square of the displacement of the COP were measured. The power spectrum of the COP movement was assessed. Subjective improvement of body balance was graded as worsened (−2), slightly worsened (−1), unchanged (0), slightly improved (+1) and improved (+2) in comparison with that without nGVS. In each session, the velocity of the COP movement was significantly improved for 6 h after the stimulus had ceased (P < 0.01). Concomitantly, the mean frequency of the COP power spectrum was significantly reduced in the anterior-posterior axis (P < 0.05). Subjective symptoms of imbalance were improved during the post-Stimulation effect (P < 0.05). nGVS leads to an improvement in body balance that lasts for several hours after the end of the stimulus in BV patients with a reduction in the high-frequency components of their postural movement. This trial was registered with the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMINCTR: UMIN000028054)
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Data_Sheet_1_Noisy Galvanic Vestibular Stimulation Sustainably Improves Posture in Bilateral Vestibulopathy.docx
2018Co-Authors: Chisato Fujimoto, Naoya Egami, Tatsuya Yamasoba, Yoshiharu Yamamoto, Takuya Kawahara, Yukari Uemura, Shin-ichi IwasakiAbstract:Patients with bilateral vestibulopathy (BV) suffer from persistent postural imbalance, leading to a marked decrease in quality of life and a higher risk of falls. However, so far, the effective treatments for BV are very limited. We examined whether long-term noisy galvanic Vestibular Stimulation (nGVS) keeps improving body balance after the cessation of the stimulus in BV patients. Thirteen BV patients received nGVS for 30 min with a lower intensity than the intensity at which they feel any cutaneous sensations, and their postural movement was monitored for 6 h after the stimuli. The same session was repeated at 14-day intervals. Stance tasks on two legs were performed with eyes closed. The velocity of the center of pressure (COP) movement, the area enclosed by the COP movement, and the root mean square of the displacement of the COP were measured. The power spectrum of the COP movement was assessed. Subjective improvement of body balance was graded as worsened (−2), slightly worsened (−1), unchanged (0), slightly improved (+1) and improved (+2) in comparison with that without nGVS. In each session, the velocity of the COP movement was significantly improved for 6 h after the stimulus had ceased (P < 0.01). Concomitantly, the mean frequency of the COP power spectrum was significantly reduced in the anterior-posterior axis (P < 0.05). Subjective symptoms of imbalance were improved during the post-Stimulation effect (P < 0.05). nGVS leads to an improvement in body balance that lasts for several hours after the end of the stimulus in BV patients with a reduction in the high-frequency components of their postural movement. This trial was registered with the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMINCTR: UMIN000028054).
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noisy galvanic Vestibular Stimulation induces a sustained improvement in body balance in elderly adults
Scientific Reports, 2016Co-Authors: Chisato Fujimoto, Naoya Egami, Makoto Kinoshita, Tatsuya Yamasoba, Fumiharu Togo, Yoshiharu Yamamoto, Yukari Uemura, Teru Kamogashira, Shin-ichi IwasakiAbstract:Vestibular dysfunction causes postural instability, which is prevalent in the elderly. We previously showed that an imperceptible level of noisy galvanic Vestibular Stimulation (nGVS) can improve postural stability in patients with bilateral vestibulopathy during the stimulus, presumably by enhancing Vestibular information processing. In this study, we investigated the after-effects of an imperceptible long-duration nGVS on body balance in elderly adults. Thirty elderly participants underwent two nGVS sessions in a randomised order. In Session 1, participants received nGVS for 30 min twice with a 4-h interval. In Session 2, participants received nGVS for 3 h. Two-legged stance tasks were performed with eyes closed while participants stood on a foam rubber surface, with and without nGVS, and parameters related to postural stability were measured using posturography. In both sessions, the postural stability was markedly improved for more than 2 h after the cessation of the stimulus and tended to decrease thereafter. The second Stimulation in Session 1 caused a moderate additional improvement in body balance and promoted the sustainability of the improvement. These results suggest that nGVS can lead to a postural stability improvement in elderly adults that lasts for several hours after the cessation of the stimulus, probably via Vestibular neuroplasticity.
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noisy Vestibular Stimulation improves body balance in bilateral vestibulopathy
Neurology, 2014Co-Authors: Shin-ichi Iwasaki, Chisato Fujimoto, Makoto Kinoshita, Fumiharu Togo, Yoshiharu Yamamoto, Yukako Yoshifuji, Tatsuya YamasobaAbstract:Objective: To examine the effect of an imperceptible level of galvanic Vestibular Stimulation (GVS), delivered as zero-mean current noise (noisy GVS), on postural performance in healthy subjects as well as in patients with bilateral peripheral Vestibular dysfunction. Methods: White noise GVS with an amplitude ranging from 0 to 1,000 μA was applied in 21 healthy subjects and 11 patients with bilateral Vestibular dysfunction. Two-legged stance tasks were performed with the eyes closed during a 60-second period, which consisted of a baseline period without Stimulation and a Stimulation period with GVS. We examined 3 parameters: the velocity, the envelopment area, and the root mean square (RMS) of the center of pressure. Results: White noise GVS improved all 3 parameters in 76% of healthy subjects. The amplitude of the optimal stimulus was 281 ± 40 μA, and it improved the velocity, area, and RMS by 18.4% ± 2%, 37.9% ± 3.5%, and 20.4% ± 2.2%, respectively ( p p Conclusions: Noisy GVS is effective in improving postural stability in healthy subjects as well as in patients with bilateral Vestibular dysfunction. Classification of evidence: This study provides Class IV evidence that in patients with bilateral Vestibular dysfunction, an imperceptible level of noisy GVS may improve postural stability.
Hansotto Karnath - One of the best experts on this subject based on the ideXlab platform.
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visual perception of one s own body under Vestibular Stimulation using biometric self avatars in virtual reality
PLOS ONE, 2019Co-Authors: Hansotto Karnath, Simone Claire Molbert, Anna Katharina Klaner, Joachim Tesch, Katrin E Giel, Hong Yu Wong, Betty J MohlerAbstract:Background and purpose Vestibular input is projected to "multisensory (Vestibular) cortex" where it converges with input from other sensory modalities. It has been assumed that this multisensory integration enables a continuous perception of state and presence of one’s own body. The present study thus asked whether or not Vestibular Stimulation may impact this perception. Methods We used an immersive virtual reality setup to realistically manipulate the length of extremities of first person biometric avatars. Twenty-two healthy participants had to adjust arms and legs to their correct length from various start lengths before, during, and after Vestibular Stimulation. Results Neither unilateral caloric nor galvanic Vestibular Stimulation had a modulating effect on the perceived size of own extremities. Conclusion Our results suggest that Vestibular Stimulation does not directly influence the explicit somatosensory representation of our body. It is possible that in non-brain-damaged, healthy subjects, changes in whole body size perception are principally not mediated by Vestibular information. Alternatively, visual feedback and/or memory may dominate multisensory integration and thereby override possibly existing modulations of body perception by Vestibular Stimulation. The present observations suggest that multisensory integration and not the processing of a single sensory input is the crucial mechanism in generating our body representation in relation to the external world.
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cerebral representations for egocentric space functional anatomical evidence from caloric Vestibular Stimulation and neck vibration
NeuroImage, 2001Co-Authors: G Bottini, Hansotto Karnath, Giuseppe Vallar, R Sterzi, C D Frith, Richard S J Frackowiak, E PaulesuAbstract:The internal representation of space involves the integration of different sensory inputs-visual, somatosensory/proprioceptive, Vestibular-yielding reference frames which are not based on individual peripheral sensory codes, being organized instead in ego-centred (e.g. head, trunk, arm) and object- or environment-centred coordinates. Lateralized or direction-specific Stimulation of peripheral sensory systems, such as caloric Vestibular Stimulation (CVS), posterior neck muscle mechanical vibration (NV) and optokinetic Stimulation, can induce a distortion of egocentric coordinates, causing, for example, a deviation of the subjective straight ahead in pointing tasks. Appropriate forms of this Stimulation can also temporarily improve a variety of pathological manifestations of unilateral neglect. We used PET measurements of regional cerebral blood flow changes in normal volunteers to measure the brain responses shared by CVS and NV. We show that somatosensory areas of the perisylvian cortex including the insula and retroinsular cortex, the temporoparietal junction and somatosensory area II receive signals from both sensory channels. We propose that these anatomical sites contribute to egocentric representation of space.
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subjective body orientation in neglect and the interactive contribution of neck muscle proprioception and Vestibular Stimulation
Brain, 1994Co-Authors: Hansotto KarnathAbstract:Three patients with a right, predominantly parietal lesion and marked left-sided neglect without visual field defects were asked to direct a laser point to the position which they felt to lie exactly ‘straight ahead’ of their bodies' orientation. Whereas in both light and darkness, the subjective body orientation was close to the objective body position in the control groups, the three neglect patients localized the body’s sagittal midplane-15° to the right of the objective orientation. No relevant differences of ‘straight ahead’ were found between the neglect patients and controls in the vertical plane. The neglect patients' horizontal displacement of sagittal midplane to the right could be compensated for either by neck muscle vibration or by caloric Vestibular Stimulation on the left side. When Vestibular Stimulation was combined with neck muscle vibration, the horizontal deviation linearly combined by adding or neutralizing the effects observed when both types of Stimulation were applied exclusively in the control groups as well as in the neglect patients. Moreover, data analysis revealed that the neglect patients' ipsilesionally displaced subjective body orientation does not result from a disturbed primary perception or disturbed transmission of the Vestibular or proprioceptive input from the periphery. The present results support the hypothesis that the essential aspect leading to neglect in brain-damaged patients is a disturbance of those cortical structures that are crucial for transforming the sensory input coordinates from the peripheral sensory organs—here the retina, neck muscle spindles and cupulae—into an egocentric, body-centred coordinate frame of reference. In neglect patients the coordinate transformation seems to work with a systematic error and deviation of the spatial reference frame to the ipsilesional side leading to a corresponding displacement of subjective localization of body orientation. It can be concluded further that neck muscle proprioception and Vestibular Stimulation directly interact in contributing to the subject's mental representation of space. The data suggest that the afferent information from these different input channels is used simultanenously for computing egocentric, body-centred coordinates that allow us to determine our body position in space.
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subjective body orientation in neglect and the interactive contribution of neck muscle proprioception and Vestibular Stimulation
Brain, 1994Co-Authors: Hansotto KarnathAbstract:Three patients with a right, predominantly parietal lesion and marked left-sided neglect without visual field defects were asked to direct a laser point to the position which they felt to lie exactly 'straight ahead' of their bodies' orientation. Whereas in both light and darkness, the subjective body orientation was close to the objective body position in the control groups, the three neglect patients localized the body's sagittal midplane approximately 15 degrees to the right of the objective orientation. No relevant differences of 'straight ahead' were found between the neglect patients and controls in the vertical plane. The neglect patients' horizontal displacement of sagittal midplane to the right could be compensated for either by neck muscle vibration or by caloric Vestibular Stimulation on the left side. When Vestibular Stimulation was combined with neck muscle vibration, the horizontal deviation linearly combined by adding or neutralizing the effects observed when both types of Stimulation were applied exclusively in the control groups as well as in the neglect patients. Moreover, data analysis revealed that the neglect patients' ipsilesionally displaced subjective body orientation does not result from a disturbed primary perception or disturbed transmission of the Vestibular or proprioceptive input from the periphery. The present results support the hypothesis that the essential aspect leading to neglect in brain-damaged patients is a disturbance of those cortical structures that are crucial for transforming the sensory input coordinates from the peripheral sensory organs--here the retina, neck muscle spindles and cupulae--into an egocentric, body-centred coordinate frame of reference. In neglect patients the coordinate transformation seems to work with a systematic error and deviation of the spatial reference frame to the ipsilesional side leading to a corresponding displacement of subjective localization of body orientation. It can be concluded further that neck muscle proprioception and Vestibular Stimulation directly interact in contributing to the subject's mental representation of space. The data suggest that the afferent information from these different input channels is used simultaneously for computing egocentric, body-centred coordinates that allow us to determine our body position in space.
Hamish G Macdougall - One of the best experts on this subject based on the ideXlab platform.
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pre adaptation to noisy galvanic Vestibular Stimulation is associated with enhanced sensorimotor performance in novel Vestibular environments
Frontiers in Systems Neuroscience, 2015Co-Authors: Steven T Moore, Valentina Dilda, Tiffany R Morris, Don A Yungher, Hamish G Macdougall, Hamish G Macdougall, Steven T Moore, Valentina DildaAbstract:Performance on a visuomotor task in the presence of novel Vestibular Stimulation was assessed in nine healthy subjects. Four subjects had previously been adapted to 120 min exposure to noisy Galvanic Vestibular Stimulation (GVS) over 12 weekly sessions of 10 min; the remaining five subjects had never experienced GVS. Subjects were seated in a flight simulator and asked to null the roll motion of a visual bar presented on a screen using a joystick. Both the visual bar and the simulator cabin were moving in roll with a pseudorandom (sum of sines) waveform that were uncorrelated. The cross correlation coefficient, which ranges from 1 (identical waveforms) to 0 (unrelated waveforms), was calculated for the ideal (perfect nulling of bar motion) and actual joystick input waveform for each subject. The cross correlation coefficient for the GVS-adapted group (0.90 [SD 0.04]) was significantly higher (t[8] = 3.162; p = 0.013) than the control group (0.82 [SD 0.04]), suggesting that prior adaptation to GVS was associated with an enhanced ability to perform the visuomotor task in the presence of novel Vestibular noise.
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central adaptation to repeated galvanic Vestibular Stimulation implications for pre flight astronaut training
PLOS ONE, 2014Co-Authors: Valentina Dilda, Tiffany R Morris, Don A Yungher, Hamish G Macdougall, Steven T MooreAbstract:Healthy subjects (N=10) were exposed to 10-min cumulative pseudorandom bilateral bipolar Galvanic Vestibular Stimulation (GVS) on a weekly basis for 12 weeks (120 min total exposure). During each trial subjects performed computerized dynamic posturography and eye movements were measured using digital video-oculography. Follow up tests were conducted 6 weeks and 6 months after the 12-week adaptation period. Postural performance was significantly impaired during GVS at first exposure, but recovered to baseline over a period of 7–8 weeks (70–80 min GVS exposure). This postural recovery was maintained 6 months after adaptation. In contrast, the roll vestibulo-ocular reflex response to GVS was not attenuated by repeated exposure. This suggests that GVS adaptation did not occur at the Vestibular end-organs or involve changes in low-level (brainstem-mediated) vestibulo-ocular or vestibulo-spinal reflexes. Faced with unreliable Vestibular input, the cerebellum reweighted sensory input to emphasize veridical extra-Vestibular information, such as somatosensation, vision and visceral stretch receptors, to regain postural function. After a period of recovery subjects exhibited dual adaption and the ability to rapidly switch between the perturbed (GVS) and natural Vestibular state for up to 6 months.
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what galvanic Vestibular Stimulation actually activates
Frontiers in Neurology, 2012Co-Authors: Ian S Curthoys, Hamish G MacdougallAbstract:In a recent paper in Frontiers Cohen et al. (2012) asked “What does galvanic Vestibular Stimulation actually activate?” and concluded that galvanic Vestibular Stimulation (GVS) causes predominantly otolithic behavioural responses. In this Perspective paper we show that such a conclusion does not follow from the evidence. The evidence from neurophysiology is very clear: galvanic Stimulation activates primary otolithic neurons as well as primary semicircular canal neurons (Kim and Curthoys, 2004). Irregular neurons are activated at lower currents. The answer to what behaviour is activated depends on what is measured and how it is measured, including not just technical details, such as the frame rate of video, but the exact experimental context in which the measurement took place (visual fixation vs total darkness). Both canal and otolith dependent responses are activated by GVS.
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effects of galvanic Vestibular Stimulation on cognitive function
Experimental Brain Research, 2012Co-Authors: Valentina Dilda, Ian S Curthoys, Hamish G Macdougall, Steven T MooreAbstract:Although imaging studies suggest activation of cortical areas by Vestibular input, there is little evidence of an adverse effect of non-veridical Vestibular input on cognitive function. To test the hypothesis that degraded Vestibular afferent input adversely affects cognition, we compared performance on a cognitive test battery in a group undergoing suprathreshold bilateral bipolar Galvanic Vestibular Stimulation (GVS) with a control group receiving no GVS or subthreshold Stimulation. The battery consisted of six cognitive tests as follows: reaction time, dual tasking, Stroop, mental rotation, perspective-taking and matching-to-sample, as well as a simple visuomotor (manual tracking) task. Subjects performed the test battery before, during and after suprathreshold GVS exposure or subthreshold Stimulation. Suprathreshold GVS significantly increased error rate for the match-to-sample and perspective-taking tasks relative to the subthreshold group, demonstrating a negative effect of non-veridical Vestibular input in these specific cognitive tasks. Reaction time, dual tasking, mental rotation and manual tracking were unaffected by GVS exposure. The adverse effect of suprathreshold GVS on perspective taking but not mental rotation is consistent with imaging studies, which have demonstrated that egocentric mental transformations (perspective taking) occur primarily in cortical areas that receive Vestibular input (the parietal–temporal junction and superior parietal lobule), whereas object-based transformations (mental rotation) occur in the frontoparietal region. The increased error rate during the match-to-sample task is likely due to interference with hippocampal processing related to spatial memory, as suggested by imaging studies on Vestibular patients.
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galvanic Vestibular Stimulation as an analogue of spatial disorientation after spaceflight
Aviation Space and Environmental Medicine, 2011Co-Authors: Steven T Moore, Valentina Dilda, Hamish G MacdougallAbstract:BACKGROUND: Exposure to microgravity adversely affects performance of astronaut pilots; a review of the first 100 Shuttle missions found that touchdown speed was above specified limits in 20% of landings, in contrast to near ideal performance in preflight high-fidelity Shuttle simulations. Ground-based simulators emphasize spacecraft handling abilities, but do not recreate the effects of extended weightlessness on sensorimotor function. The aim of this study was to validate an analogue of the sensorimotor effects of microgravity using pseudorandom bilateral bipolar galvanic Vestibular Stimulation (GVS) during Shuttle landing simulations. METHODS: Pilot performance was assessed during simulated Shuttle landings in the Vertical Motion Simulator at NASA Ames Research Center, Moffett Field, CA (used for astronaut pilot training). Subjects (N = 11) flew eight pairs of identical landing profiles (final approach and touchdown), with and without GVS, presented in a pseudorandom order. RESULTS: Touchdown speed was on target (204 kn) without GVS [203.8 kn], but increased significantly during GVS exposure 1208.5 kn] and was at the upper limit (209 kn) of the target range. The adverse effects of GVS on pilot performance were obvious. Unsuccessful (crash) landings increased from 2.3% (2/88) without GVS to 9% (7/88) with GVS. Hard landings, with touchdown speed in the 'red' (unacceptable) range (> 214 kn), almost doubled from 14 (15.9%) without GVS to 27 (30.7%) with GVS. CONCLUSION: GVS was an effective analogue of decrements in postflight Shuttle pilot performance.
Vaughan G Macefield - One of the best experts on this subject based on the ideXlab platform.
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Vestibular modulation of muscle sympathetic nerve activity assessed over a 100 fold frequency range of sinusoidal galvanic Vestibular Stimulation
Journal of Neurophysiology, 2019Co-Authors: Natasha Singh, Elie Hammam, Vaughan G MacefieldAbstract:Vestibulosympathetic reflexes have been documented in experimental animals and humans. Here we show that sinusoidal galvanic Vestibular Stimulation, a means of selectively exciting Vestibular affer...
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modulation of muscle sympathetic bursts by sinusoidal galvanic Vestibular Stimulation in human subjects
Experimental Brain Research, 2006Co-Authors: Leah R Bent, Philip S Bolton, Vaughan G MacefieldAbstract:There is controversy as to whether the vestibulosympathetic reflexes demonstrated in experimental animals actually exist in human subjects. While head-down neck flexion and off-vertical axis rotation can increase muscle sympathetic nerve activity (MSNA) in awake subjects, we recently showed that bipolar galvanic Vestibular Stimulation (GVS) does not. However, it is possible that our stimuli (2 mA, 1 s)-although capable of causing strong postural and occulomotor responses-were too brief. To address this issue we activated Vestibular afferents using continuous sinusoidal (0.5-0.8 Hz, 60-100 cycles, +/-2 mA) bipolar binaural GVS in 11 seated subjects. Sinusoidal GVS evoked robust Vestibular illusions of "rocking in a boat" or "swinging from side to side." Cross-correlation analysis revealed a cyclic modulation of MSNA ranging from 31 to 86% across subjects (mean +/- SE 58 +/- 5%), with total MSNA increasing by 156 +/- 19% (P = 0.001). Furthermore, we documented de novo synthesis of sympathetic bursts that were coupled to the sinusoidal input, such that two bursts-rather than the obligatory single burst-could be generated within a cardiac interval. This demonstrates that the human Vestibular apparatus exerts a potent facilitatory influence on MSNA that potentially operates independently of the baroreceptor system.
