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

University of Zurich

Overview

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.

Study Type

INTERVENTIONAL

Allocation

Purpose

BASIC_SCIENCE

Masking

NONE

Conditions

Vestibular Perception

Interventions

perception of vertical after static roll-tilt over 5minOTHER

subjects will indicate perceived direction of vertical after 5min of static whole-body roll-tilt.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: 1. ages 18-65 years 2. informed consent 3. absence of exclusion criteria Exclusion Criteria: 1. peripheral-vestibular deficit 2. disturbed consciousness 3. history of sensory deficits 4. visual field deficits 5. other neurological or systemic disorder which can cause dementia or cognitive dysfunction 6. intake of antidepressants, sedatives, or neuroleptics 7. pregnancy, unless excluded by a negative pregnancy test 8. known neck pain or status post neck trauma

Outcomes

Primary Outcomes

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.

Time frame: measurements will be obtained over periods of 5min in a single session and day

Secondary Outcomes

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.

Time frame: measurements will be obtained over periods of 5min in a single session and day

Data from ClinicalTrials.gov

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