Subthreshold Vestibular Stimulation as a Strategy for Rehabilitation
Creighton University
Summary
The nervous system responds to changes in external or internal conditions by altering the behavior of neurons through multiple forms of neural plasticity. A specific form of plasticity, "homeostatic plasticity", stabilizes neural activity by driving the excitability of neurons toward a "set-point" level of activity. Over the last six years, new data have come to light showing that the vestibular system also possess a robust capacity to modulate sensitivity to self-motion cues in response to prolonged periods of motion. Collectively, these studies have demonstrated a capacity to use motion perturbations (i.e., low, or high levels of vestibular stimulation) to dynamically adjust the sensitivity of the vestibular system on both the single neuron and behavioral levels. The ability to use subthreshold motion stimuli to drive plasticity in the vestibular system motivates this study. The investigators aim to determine the impact of subthreshold motion on (a) balance performance and (b) balance training in individuals with peripheral vestibular hypofunction.
Description
The investigators aim to test (1) if sub threshold motion improves motion perception, (2) if sub threshold motion improves balance performance, and (3) if sub threshold motion prior to balance training leads to improved balance performance. Twenty-four subjects with peripheral vestibular hypofunction (12 with bilateral and 12 with unilateral hypofunction) and twenty-four healthy control participants will complete the study. Each participant will complete four visits to the laboratory. Day 1 will measure the capacity to modify balance and self-motion perception after a single block of subthresh…
Eligibility
- Age range
- 19–89 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria for Bilateral Vestibular Hypofunction: 1\. Bilateral lateral canal VOR gain of \< 0.8 on video head impulse testing OR bilateral positive bedside head impulse test Inclusion Criteria for Unilateral Vestibular Hypofunction: 1\. Unilateral yaw aVOR gain of \< 0.8 on video head impulse testing OR unilateral positive bedside head impulse test Inclusion Criteria for all Participants: 1. Must be able to stand for 5 minutes unassisted 2. No leg or foot amputations 3. No lower limb braces 4. Not currently pregnant by self-report 5. Weight \<= 300 pounds (due to limitations of t…
Interventions
- BehavioralSubthreshold Vestibular Conditioning
Subthreshold vestibular conditioning will be performed while seated on a motion platform and blindfolded. The stimulus will consist of a pseudorandom sum-of-sinusoids roll tilt motion (\~0.08 to 1 Hz) delivered at a peak velocity equal to 57.4% of the measured baseline roll tilt perceptual threshold (e.g., 0.574°/s for a 1 °/s threshold). The participant will be informed that while the chair may vibrate or move slightly, the motion will not occur in any particular direction.
- BehavioralBalance Training
Balance training will consist of progressive exposure to continuous one-dimensional roll pseudorandom platform perturbations delivered using a 6DoF motion platform. Participants will stand on a MOOG hexapod motion platform and will be secured using a safety harness tethered to the ceiling and a full enclosure of safety rails. Roll tilt perturbations will be progressed by gradually increasing the displacement/velocity/acceleration of the platform motion.
- OtherBalance Training Plus Subthreshold Conditioning
Subthreshold vestibular conditioning will be performed while seated on a motion platform and blindfolded prior to each bout of balance training. Subthreshold conditioning will consist of a pseudorandom sum-of-sinusoids roll tilt motion (\~0.08 to 1 Hz) delivered at a peak velocity equal to 57.4% of the measured baseline roll tilt perceptual threshold (e.g., 0.574°/s for a 1 °/s threshold). The participant will be informed that while the chair may vibrate or move slightly, the motion will not occur in any particular direction. Balance training will consist of progressive exposure to continuous two-dimensional (2D) pseudorandom platform perturbations delivered using a 6DoF motion platform. 2D perturbations (roll and pitch tilt) will be progressed by gradually increasing the displacement/velocity/acceleration of the motion stimulus.
Location
- Creighton UniversityOmaha, Nebraska