Directional asymmetries and age effects in human self-motion perception

Area of Science:

• Neuroscience
• Human Perception
• Vestibular System

Background:

• Vestibular reflexes exhibit directional asymmetries, aiding in diagnosing vestibular lesions.
• However, asymmetries in human vestibular perception remain poorly understood.

Purpose of the Study:

• To quantify potential directional asymmetries in human vestibular perception.
• To determine if vestibular sensitivities are direction-specific.

Main Methods:

• Measured vestibular perception thresholds in 24 healthy adults (21-68 years) using sinusoidal acceleration stimuli (sway, surge, heave, yaw).
• Employed a forced-choice technique to determine directional thresholds and presented null stimuli to assess response bias.
• Applied multiple models, including direction-specific sensitivity models, to analyze the data.

Main Results:

• Significant directional asymmetry in dynamic response was observed in 92% of subjects across at least one motion type.
• Directional asymmetries were generally consistent within individuals but varied across the population.
• A model incorporating direction-specific sensitivities provided a better fit to the data in 86% of runs.
• Age influenced thresholds for surge and sway, with higher values in individuals over 50.

Conclusions:

• Human vestibular perception demonstrates significant directional asymmetries, suggesting direction-specific sensitivities.
• These asymmetries are generally consistent within individuals and may be influenced by age for certain motion types.
• The findings highlight the complexity of vestibular perception and its potential clinical implications.