Somatosensory loss increases vestibulospinal sensitivity (original) (raw)
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Somatosensory influence on postural response to galvanic vestibular stimulation
We investigated how postural responses to galvanic vestibular stimulation were affected by standing on a translating support surface and by somatosensory loss due to diabetic neuropathy. We tested the hypothesis that an unstable surface and somatosensory loss can result in an increase of vestibulospinal sensitivity. Bipolar galvanic vestibular stimulation was applied to subjects who were standing on a force platform, either on a hard, stationary surface or during a backward platform translation (9 cm, 4.2 cm/s). The intensity of the galvanic stimulus was varied from 0.25 to 1mA. The amplitude of the peak body CoP displacement in response to the galvanic stimulus was plotted as a function of stimulus intensity for each individual. A larger increase in CoP displacement to a given increase in galvanic current was interpreted as an increase of vestibulospinal sensitivity. Subjects with somatosensory loss in the feet due to diabetes showed higher vestibulospinal sensitivity than healthy subjects when tested on a stationary support surface. Control subjects and patients with somatosensory loss standing on translating surface also showed increased galvanic response gains compared to stance on a stationary surface. The severity of the somatosensory loss in the feet correlated with the increased postural sensitivity to galvanic vestibular stimulation. These results showed that postural responses to galvanic vestibular stimulus were modified by somatosensory information from the surface. Somatosensory loss due to diabetic neuropathy and alteration of somatosensory input during stance on translating support surface resulted in increased vestibulospinal sensitivity.
The Journal of physiology, 1997
1. We have studied the effects of changes in posture on the motor response to galvanic vestibular stimulation (GVS). The purpose of the experiments was to investigate whether the function of the GVS-evoked response is to stabilize the body or the head in space. Subjects faced forwards with eyes closed standing with various stance widths and sitting. In all cases the GVS-evoked response consisted of a sway of the body towards the anodal ear. 2. In the first set of experiments the response was measured from changes in (i) electromyographic activity of hip and ankle muscles, (ii) the lateral ground reaction force, and (iii) lateral motion of the body at the level of the neck (C7). For all measurements the response became smaller as the feet were placed further apart. 3. In the second set of experiments we measured the GVS-evoked tilts of the head, torso and pelvis. The basic response consisted of a tilt in space (anodal ear down) of all three segments. The head tilted more than the tru...
Scientific reports, 2016
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 an...
Magnitude effects of galvanic vestibular stimulation on the trajectory of human gait
Neuroscience Letters, 2000
This study examines the contribution of the vestibular system during different magnitudes of galvanic vestibular stimulation (GVS) during human walking. Anodal threshold levels of GVS were determined for right and left sides for each subject. Seven conditions were tested (no stimulation, left and right anode stimulation) at one, two and three times threshold. GVS was delivered to the mastoid processes at ®rst heel contact and continued for the duration of the trial. All subjects responded by deviating towards the anode while walking. In addition, the magnitude of deviation increased as the stimulus intensity increased. Our results demonstrate that the vestibular system is sensitive to GVS intensity changes and responds by altering the magnitude of the response accordingly. These data provide a strong argument in support of a signi®cant role for vestibular information during dynamic tasks. q
Effects of Galvanic vestibular stimulation on cognitive function
Experimental Brain Research, 2012
You might find this additional info useful... 35 articles, 17 of which can be accessed free at: This article cites /content/108/1/300.full.html#ref-list-1 2 other HighWire hosted articles This article has been cited by [PDF] [Full Text] [Abstract] , July 1, 2013; 110 (1): 86-94. cadence Muscle-specific modulation of vestibular reflexes with increased locomotor velocity and [PDF] [Full Text] [Abstract] , November 27, 2013; 33 (48): 18987-18998. J. Neurosci.
Experimental Brain Research, 1993
Application of a small (around 1 mA), constant electric current between the mastoid processes (galvanic stimulation) of a standing subject produces enhanced body sway in the approximate direction of the ear behind which the anode is placed. We examined the electromyographic (EMG) responses evoked by such stimulation in the soleus and in the triceps brachii muscles. For soleus, subjects stood erect, with their eyes closed, leaning slightly forward. The head was turned approximately 90° to the right or left relative to the feet. In averaged records (n=40), current pulses of 25 ms or longer modulated the EMG in a biphasic manner: a small early component (latency 62±2.4 ms, mean ± SEM) was followed by a larger late component (latency 115±5.2ms) of opposite sign, which was appropriate to produce the observed body sway. The early component produced no measurable body movement. Lengthening the duration of the stimulus pulse from 25 to 400 ms prolonged the late component of the response but had little effect on the early component. Short- and long-latency EMG responses were also evoked in the triceps brachii muscle if subjects stood on a transversely pivoted platform and had to use the muscle to maintain their balance in the anteroposterior plane by holding a fixed handle placed by the side of their hip. The latency of the early component was 41±2.6 ms; the latency of the late component was 138±4.3 ms and was again of appropriate sign for producing the observed body sway. Galvanic stimulation evoked no comparable responses in either triceps brachii or soleus muscles if these muscles were not being used posturally. The responses were most prominent if vestibular input provided the dominant source of information about postural stability, and were much smaller if subjects lightly touched a fixed support or opened their eyes. The difference in latency between the onset of the early component of the response in arm and leg muscles suggests that this part of the response uses a descending pathway which conducts impulses down the spinal cord with a velocity comparable with that of the fast conducting component of the corticospinal tract. The late component of the EMG response occurs earlier in the leg than the arm. We suggest that it forms part of a patterned, functional response which is computed independently of the early component.
Diabetic Polyneuropathy May Increase the Handicap Related to Vestibular Disease
2009
Background and Aims. We undertook this study to assess the influence of diabetic peripheral neuropathy on self-reported disability and postural control during quiet stance of patients with peripheral vestibular disease, before and after a standardized program of vestibular rehabilitation (Cawthorne & Cooksey exercises). Methods. Twenty patients with peripheral vestibular disease participated in the study (mean age 56 AE 7.8 years), 10 with and 10 without peripheral neuropathy (age matched). The Dizziness Handicap Inventory and static posturography (eyes open/closed and firm/ soft surface) were evaluated prior to rehabilitation and at week 7 of follow-up. Results. Compared to patients without neuropathy, patients with neuropathy had more time elapsed since the diabetes was diagnosed, higher glycemia and HbAc level and higher composite scores on the Dizziness Handicap Inventory, but similar results on static posturography. After rehabilitation, although scores on the Dizziness Handicap Inventory decreased in the two groups, the difference between them persisted. In patients with neuropathy, static posturography showed improvement of postural control only with the eyes closed and soft surface, whereas in patients without neuropathy the postural control improved during all sensory conditions (eyes open/closed and firm/soft surface). Conclusions. In diabetic patients with peripheral vestibular disease, peripheral neuropathy contributes to self-reported disability and may interfere with complete balance recovery.