Effect of Vestibular Perceptual Learning on Vestibular Thresholds and Balance

Ohio State University30 enrolled

Overview

The intervention being studied is a minimal risk perceptual learning protocol delivered in an academic laboratory setting; the goal of the intervention is to improve the perception of passive whole-body tilts and/or translations, as well as balance, by providing feedback following passive tilts or translations of the body. The protocol lasts a total of \~45 days: Day 1 includes a pre-test assessment of perception and balance, as well as 100 repetitions of training, Days 2-7 each include 400 repetitions of training, and Day 6 includes only post-test assessments of perception and balance.

Three training paradigms will be evaluated in 3 cohorts of older 10 adults (N=30; Ages 65 to 89). Motion for all three training paradigms will be provided by a 12" Moog 6DoF motion platform. The first training protocol will be a roll tilt training protocol previously shown to reduce roll tilt thresholds. The second training protocols will be an inter-aural translation training protocol. The third training protocol will include half roll tilt training and half inter-aural translation training. As such, each cohort will perform perceptual training using a combination of the following training parameters: 1. Tilt Training: Training stimuli will be either a roll tilt to the left or right. 2. Translation Training: Training stimuli will be either a translation to the left or right. 3. Both Tilt Training and Translation Training will include half roll tilt training and half inter-aural translation training. 4. Older adults will train using a (A) 2-Down/1-Up (i.e., the size of the tilt stimulus decreases after 2 consecutive correct responses and increases after each incorrect response), 5. Feedback Method: During training, the accuracy of perceptual judgement (e.g., recognizing a left vs. right tilt motion) will be provided to the subject using a combination of auditory feedback and visual feedback. Auditory feedback will inform the subject whether they were correct or incorrect; visual feedback will be provided by the return motion with eyes open and lights on. The targeted dates for each assessment and intervention period are shown, however, to permit greater adherence to the study protocol, tests of retention will be accepted if they occur within 7 to 10 days after the post-test (for the one-week follow-up) or 30 to 40 days after the post-test (for the one-month follow-up). 1. Intervention-First arm: 1. Day 1: Pre-test assessment 2. Days 2-7: Active perceptual learning intervention 3. Day 8: Post-test assessment 4. Day 15: One-week retention assessment 5. Day 38: One-month retention assessment 6. Days 39-44: Control intervention 7. Day 45: Post-test assessment 2. Control-First arm: 1. Day 1: Pre-test assessment 2. Days 2-7: Control intervention 3. Day 8: Post-test / Pre-Test assessment 4. Days 9 to 14: Active perceptual learning intervention 5. Day 15: Post-test assessment 6. Day 22: One-week retention assessment 7. Day 45: One-month retention assessment

Interventions

Roll Tilt TrainingBEHAVIORAL

The participants will be tilted and asked to indicate their perceived direction of self-motion (e.g., left or right). Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject response, and thus vestibular (i.e., self-motion) perception is required to judge the direction of the tilt stimulus. After each trial, a three second period of rest will be given. Each day of training will include four blocks of one-hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.

Translation TrainingBEHAVIORAL

The participants will be translated and asked to indicate their perceived direction of self-motion (e.g., left or right). Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds, and thus vestibular (i.e., self-motion) perception is required to judge the direction of the translation stimulus. After each trial, a three second period of rest will be given. Each day of training will include four blocks of one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.

Both Tilt and Translation TrainingBEHAVIORAL

The participants will be equally tilted and translated and asked to indicate their perceived direction of self-motion (e.g., left or right) . Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds. After each trial, a three second period of rest will be given. Each day of training will include four blocks; 2 blocks of roll tilt and 2 blocks of translation - one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.

Placebo ControlBEHAVIORAL

Participants will complete home-based exercises that are not associated with improving vestibular perception or balance (e.g. saccades, smooth pursuit). Participants will sit in a comfortable chair facing out into a living space. They will then find a stationary object to the right and to the left of themselves as well as above and below their line of sight. Without moving their heads, they will look back and forth and up and down between the objects. Participants will complete a total of 400 eye motions per day for six days.

Eligibility

Sex: ALLMin age: 65 YearsMax age: 89 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Must be able to stand * No leg or foot amputations * No lower limb braces * Not currently feeling dizzy/lightheaded * Not currently pregnant by self-report * Weight \<= 275 pounds Exclusion Criteria: * Severe head trauma or traumatic brain injury * Any vestibular disorder (e.g., Meniere's Disease, Vestibular Migraine, Unresolved benign paroxysmal positional vertigo (BPPV), Vestibular hypofunction, except that due to aging, PPPD) as assessed by a Vestibular OtoNeurologist and Neurotologist using clinical diagnostic tests described in proposal plus any additional clinical evaluations they identify * History of seizures * Neurologic illness or condition determined by an Otoneurologist known to impact vestibular or balance function(e.g., stroke, neurodegenerative disorders, demyelinating illness) * Major psychiatric (e.g., panic disorder, psychosis, etc.) disorder * Any of the following eye diseases or conditions: amblyopia (or "lazy eye") or history of amblyopia, diagnosis of age-related macular degeneration, retina dystrophy, glaucoma, cataracts, or any other eye condition that limits vision to worse than 20/40 * Recent (\<6 months) orthopedic injuries of the lower extremities (e.g., plantar fasciitis, ankle, knee or hip injury, back strain/herniated disc, …). * Upper extremity injuries requiring current sling immobilization * Recent surgery * Any other severe health problem (heart disease, pulmonary disease, cancer, etc.). * Vision in both eyes must be better than 20/40 with best correction * Due to the potential for nausea with some of the motion stimuli, and to protect fetus and mother, pregnant women will also be excluded from this study * Since every possible exclusionary factor cannot be predicted, additional exclusion criteria may be required

Outcomes

Primary Outcomes

Change in Vestibular Roll Tilt Perceptual Thresholds

Vestibular perceptual thresholds will be measured using forced-choice methodologies; such methods have been used extensively. Passive, whole body tilts will be delivered using a Moog motion platform. Subjects will be tilted in one of two directions (e.g., towards the left or right) in complete darkness and asked to report their perceived direction of motion. All subjects will be seated in a chair with a 5-point harness. The head will be restrained by a standard motorcycle helmet. Insert earbuds will be worn, reducing external noise by about 20 decibels (dB). To mask potential auditory directionality cues, auditory "noise" - uncorrelated with motion (amplitude, direction, or type) - will be applied at 65 dB sound pressure level (SPL). Motion stimuli will consist of single cycles of sinusoidal acceleration using published methods.