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 the investigators knowledge of how the brain combines the information of multiple sensory systems coding for spatial oriention 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). This effect could either be related to adaptation to the roll-tilted position (shifting the null position) or it could be related to changes in torsional eye position due to prolonged static roll-tilt (ocular counter-roll). While in the first case a post-tilt bias is predicted independently of the experimental paradigm used, the second hypothesis predicts a post-tilt bias only if retinal cues are integrated. In order to evaluate these hypotheses, the investigators will assess perceived vertical using both vision-dependent and vision-independent paradigms.

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

Conditions
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Adaptation Reaction

Intervention / Treatment
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* Behavioral: presentation of visual and vestibular stimuli


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: intervention arm<br>In each participant the investigators will assess verticality perception in whole-body upright position by use of the SVV, the SPV and the SHV after static roll-tilt at ±90deg over 5min. Measurements will be obtained on a motor-driven turntable and two different roll-tilt positions will be applied (±90°). A visual line (SVV), a rod (SHV) or the turntable itself will be adjusted to indicate perceived direction of vertical. A total of three measuring sessions, each lasting about 60 minutes are scheduled. | Behavioral: presentation of visual and vestibular stimuli<br>* In each participant the investigators will assess verticality perception in whole-body upright position by use of the SVV, the SPV and the SHV after static roll-tilt at ±90deg over 5min. Measurements will be obtained on a motor-driven turntable and two different roll-tilt positions will be applied (±90°). A visual line (SVV), a rod (SHV) or the turntable itself will be adjusted to indicate perceived direction of vertical. A total of three measuring sessions, each lasting about 60 minutes are scheduled.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| adjustment errors of the subjective visual/haptic/postural vertical in upright position after prolonged whole-body roll-tilt positions. | the accuracy and precision of visual vertical adjustments after prolonged roll tilt are quantified. | 10 minutes (i.e. short-term adaptation) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| changes in adjustment errors of the subjective visual vertical when providing an additional optokinetic stimulus | This is the same as in outcome 1, but an additional visual (optokinetic) stimulus is added | 10 minutes (i.e. short-term adaptation) | 
| changes in adjustment errors of the subjective haptic vertical when providing an additional optokinetic stimulus | This is the same as in outcome 1, but an additional visual (optokinetic) stimulus is added | 10 minutes (i.e. short-term adaptation) | 
| changes in adjustment errors of the subjective postural vertical when providing an additional optokinetic stimulus | This is the same as in outcome 1, but an additional visual (optokinetic) stimulus is added | 10 minutes (i.e. short-term adaptation) |