Verticality Perception - Effects of Prolonged Roll-tilt in Healthy Human Subjects

Study Overview
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Brief Summary
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The long-term goal of this research is to advance our knowledge of how the brain combines the information of multiple sensory systems coding for spatial orientation and how adaptation to vestibular imbalance influences spatial orientation. In healthy human subjects verticality perception is accurate while upright. After prolonged roll-tilt, humans show a systematic bias in perceived direction towards the previous roll-tilted position (so-called post-tilt bias). Here we evaluate different potential explanations for this bias using both vision-dependent and vision-independent paradigms of verticality perception.

Official Title
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Verticality Perception - Effects of Prolonged Roll-tilt in Healthy Human Subjects

Conditions
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Vestibular, Perception

Intervention / Treatment
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* Other: perception of vertical after static roll-tilt over 5min


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ages 18-65 years informed consent absence of exclusion criteria Exclusion Criteria: peripheral-vestibular deficit disturbed consciousness history of sensory deficits visual field deficits other neurological or systemic disorder which can cause dementia or cognitive dysfunction intake of antidepressants, sedatives, or neuroleptics pregnancy, unless excluded by a negative pregnancy test known neck pain or status post neck trauma

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Single intervention arm<br>This is the only arm in this study, measuring verticality perception after prolonged roll-tilt over 5min. | Other: perception of vertical after static roll-tilt over 5min<br>* subjects will indicate perceived direction of vertical after 5min of static whole-body roll-tilt.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Adjustment errors and trial-to-trial variability as assessed by line adjustments (subjective visual vertical (SVV)), adjustments of a rod (subjective haptic vertical (SHV)) or self-adjustments (subjective postural vertical (SPV)) after prolonged roll | In all three paradigms (SVV, SHV and SPV) the percept of direction of gravity will be assessed. Parameters will be adjustment errors (accuracy) and trial-to-trial variability (precision) based on repetitive adjustments of a luminous line (SVV) or a rod (SHV) after returning to upright position after a period of 5min in static roll-tilt at 90° left-ear down or right-ear down. During the roll-tilt period subjects remain either in the dark or observe a rotating optokinetic (random dot) pattern. Individual mean values and standard deviation (SD) will be calculated for all conditions. Adjustments with the joystick (SPV) will start from 90° ear-down positions after 5min of static roll. | measurements will be obtained over periods of 5min in a single session and day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Impact of a rotating optokinetic stimulus (velocity 60°/s) on adjustment errors as assessed by the SVV, the SHV or the SPV after 5min of static roll-tilt at +/- 90° roll. | During the 5min period with static roll at +/- 90deg ear-down positions subjects will be presented a rotating optokinetic stimulus (random dot pattern, clockwise or counter-clockwise rotation) in some conditions. Adjustment errors and trial-to-trial variability of conditions with the optokinetic stimulus will be compared to those without the optokinetic stimulus. | measurements will be obtained over periods of 5min in a single session and day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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verticality perception