Modeling postural instability with Galvanic vestibular stimulation

MacDougall, Hamish G.; Moore, Steven T.; Curthoys, Ian S.; Black, F. Owen

doi:10.1007/s00221-005-0329-y

Cited by 67 publications

(76 citation statements)

References 53 publications

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“…SVS-electromyographic (EMG) coupling was observed over the 0 to 20 Hz bandwidth coinciding with previous estimates of the dynamic range of vestibular function (Armand and Minor 2001;Grossman et al 1988;Huterer and Cullen 2002). Whole-body responses to vestibular stimulation, however, appear to follow the vestibular stimulus when frequencies Ͻ5 Hz are provided (Fitzpatrick et al 1996;Latt et al 2003;Lund and Broberg 1983;MacDougall et al 2006;Moore et al 2006;Pavlik et al 1999), with the largest responses elicited when the frequency content of the stochastic vestibular stimulus is Ͻ2 Hz (Fitzpatrick et al 1996;Pavlik et al 1999).…”

Section: Introductionsupporting

confidence: 86%

Frequency-Specific Modulation of Vestibular-Evoked Sway Responses in Humans

Dakin

Luu

Doel³

et al. 2010

Journal of Neurophysiology

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Dakin CJ, Luu BL, van den Doel K, Inglis JT, Blouin J-S. Frequency-specific modulation of vestibular-evoked sway responses in humans. J Neurophysiol 103: 1048 -1056, 2010. First published December 23, 2009 doi:10.1152/jn.00881.2009. Galvanic vestibular stimulation (GVS) results in characteristic muscle and whole-body responses in humans maintaining standing balance. However, the relationship between these two vestibular-evoked responses remains elusive. This study seeks to determine whether mechanical filtering from conversion of lower-limb muscle activity to body sway, during standing balance, can be used to attenuate sway while maintaining biphasic lower-limb muscle responses using frequency-limited stochastic vestibular stimulation (SVS). We hypothesized that SVS deprived of frequencies Ͻ2 Hz would evoke biphasic muscle responses with minimal whole-body sway due to mechanical filtering of the higher-frequency muscle responses. Subjects were exposed to five stimulus bandwidths: two meant to induce sway responses (0 -1 and 0 -2 Hz) and three to dissociate vestibular-evoked muscle responses from whole-body sway (0 -25, 1-25, and 2-25 Hz). Two main results emerged: 1) SVS-related sway was attenuated when frequencies Ͻ2 Hz were excluded, whereas multiphasic muscle and force responses were retained; and 2) the gain of the estimated transfer functions exhibited successive low-pass filtering of vestibular stimuli during conversion to muscle activity, anteroposterior (AP) moment, and sway. This successive low-pass filtering limited the transfer of signal power to frequencies Ͻ20 Hz in muscle activity, Ͻ5 Hz in AP moment, and Ͻ2 Hz in AP trunk sway. Consequently, the present results show that SVS delivered at frequencies Ͼ2 Hz to standing humans do not cause a destabilizing whole-body sway response but are associated with the typical biphasic lower-limb muscle responses.

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Section: Introductionsupporting

confidence: 86%

Frequency-Specific Modulation of Vestibular-Evoked Sway Responses in Humans

Dakin

Luu

Doel³

et al. 2010

Journal of Neurophysiology

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“…Hence, such stimulation protocol is not suitable to distinguish the vestibulo-motor responses from the balance responses in healthy or patient population, nor does it help in understanding how, or if, these two components of the GVS-evoked response are linked. Stochastic vestibular stimulation may be better suited to achieve these objectives, but this remains to be properly examined (6,22).…”

Section: Discussionmentioning

confidence: 99%

Short-duration galvanic vestibular stimulation evokes prolonged balance responses

Son¹,

Blouin²,

Inglis³

2008

Journal of Applied Physiology

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Lee Son GM, Blouin J-S, Inglis JT. Short-duration galvanic vestibular stimulation evokes prolonged balance responses. J Appl Physiol 105: 1210 -1217, 2008. First published July 31, 2008 doi:10.1152/japplphysiol.01398.2006.-The application of galvanic vestibular stimulation (GVS) evokes distinct responses in lower limb muscles involved in the control of balance. The purpose of this study was to investigate the balance and lower limb muscle responses to short-duration GVS and to determine whether these responses are modulated by small changes in center of gravity (CoG) and baseline muscle activity occurring during quiet standing. Twelve subjects stood quietly on a force plate with their feet together and were instructed to look straight ahead. One thousand twenty-four GVS stimuli (4 mA, 20-ms pulses) were delivered bilaterally to the mastoid processes in a bipolar, binaural configuration. Bilateral surface electromyography (EMG) from soleus (Sol) and tibialis anterior (TA) and ground reaction forces were recorded. EMG and force responses were trigger averaged at the onset of the GVS pulse. Short-duration GVS applied during quiet standing with the head facing forward evoked characteristic balance responses and biphasic modulation of all muscles with the same polarity for ipsilateral Sol and TA. The amplitude of the GVS-evoked muscle responses was modulated by both the estimated position of the subject's CoG and the background activation of the recorded muscle. Muscle-dependent modulations of the GVSevoked muscle responses were observed: the Sol responses decreased, while the TA responses increased when the CoG position shifted toward the heels. The well-defined balance responses evoked by short-duration GVS are important to acknowledge when studying the vestibulo-motor responses in healthy subjects and patient populations.vestibulo-motor responses; electromyography; center of pressure THE CONTRIBUTIONS OF VESTIBULAR information in the control of human balance are still being debated. Visual and somatosensory inputs provide the dominant sources of afferent information during stance, while the vestibular system is thought to have a less important role (30). Galvanic vestibular stimulation (GVS), a technique used to probe the vestibular system, has gained attention from researchers studying human balance (5, 6, 8, 9, 14, 15, 26, 29, 36, 37; for review see Ref. 11). GVS alters the firing rates of all vestibular afferents with a preference toward the irregular afferents (12), such that the anode decreases and the cathode increases afferent firing rates (13). In standing humans, binaural, bipolar GVS applied for a long duration (1-2 s) elicits a well-defined biphasic muscle response (4, 9) and a multiphasic center of pressure (CoP) response often identified by lateral sway and tilt toward the side of the anode (8, 21, 28). Short-duration GVS (20 -50 ms) have also been used to evoke vestibulomotor responses in lower and upper limb muscles engaged in balance (4, 40). Such stimuli have been thought to evoke motor respons...

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“…Subjects were also given a detailed questionnaire that inquired about the subjective experiences during GVS (modiWed and extended after Stephan et al 2005;MacDougall et al 2006, see electronic supplementary material). This questionnaire included questions about strength, direction and temporal characteristics of the illusory visual Weld and own body movements as well as the aVected body part(s) in the latter.…”

Section: Questionnairesmentioning

confidence: 99%

Influence of galvanic vestibular stimulation on egocentric and object-based mental transformations

2007

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The vestibular system analyses angular and linear accelerations of the head that are important information for perceiving the location of one's own body in space. Vestibular stimulation and in particular galvanic vestibular stimulation (GVS) that allow a systematic modiWcation of vestibular signals has so far mainly been used to investigate vestibular inXuence on sensori-motor integration in eye movements and postural control. Comparatively, only a few behavioural and imaging studies have investigated how cognition of space and body may depend on vestibular processing. This study was designed to diVerentiate the inXuence of left versus right anodal GVS compared to sham stimulation on object-based versus egocentric mental transformations. While GVS was applied, subjects made leftright judgments about pictures of a plant or a human body presented at diVerent orientations in the roll plane. All subjects reported illusory sensations of body self-motion and/ or visual Weld motion during GVS. Response times in the mental transformation task were increased during right but not left anodal GVS for the more diYcult stimuli and the larger angles of rotation. Post-hoc analyses suggested that the interfering eVect of right anodal GVS was only present in subjects who reported having imagined turning themselves to solve the mental transformation task (egocentric transformation) as compared to those subjects having imagined turning the picture in space (object-based mental transformation). We suggest that this eVect relies on shared functional and cortical mechanisms in the posterior parietal cortex associated with both right anodal GVS and mental imagery.

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Modeling postural instability with Galvanic vestibular stimulation

Cited by 67 publications

References 53 publications

Frequency-Specific Modulation of Vestibular-Evoked Sway Responses in Humans

Frequency-Specific Modulation of Vestibular-Evoked Sway Responses in Humans

Short-duration galvanic vestibular stimulation evokes prolonged balance responses

Influence of galvanic vestibular stimulation on egocentric and object-based mental transformations

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