Interaural self-motion linear velocity thresholds are shifted by roll vection

Area of Science:

• Neuroscience
• Vestibular System
• Perception

Background:

• The otolith organs in the inner ear detect both head tilt (gravity) and linear acceleration.
• The central nervous system (CNS) employs internal physics models to differentiate between tilt and translation.
• Theoretical models predict that significant illusory tilt may induce a perception of linear motion.

Purpose of the Study:

• To investigate the prediction that illusory tilt is accompanied by an illusion of linear motion.
• To measure self-motion direction-detection thresholds under varying sensory conditions.
• To assess the CNS's ability to distinguish tilt from translation under optic flow stimulation.

Main Methods:

• Participants performed interaural direction-detection tasks in darkness and during roll optokinetic stimulation.
• Stimuli involved single cycles of sinusoidal lateral acceleration.
• Generalized linear models were used for statistical analysis of detection thresholds.

Main Results:

• Interaural direction-detection thresholds shifted in opposite directions during clockwise and counterclockwise optokinetic stimulation compared to darkness.
• These shifts were statistically significant (P < 0.005).
• The results indicate a non-zero neural estimate of linear velocity during illusory tilt.

Conclusions:

• The findings support the prediction that illusory tilt can induce a perception of linear motion.
• A supra-threshold neural estimate of linear velocity contributes to translation perception during illusory tilt.
• This highlights the complex interplay between vestibular and visual systems in motion perception.