Inter-hemispheric desynchronization of the human MT+ during visually induced motion sickness

Area of Science:

• Neuroscience
• Visual Perception
• Human Motion Sensitivity

Background:

• Visually induced motion sickness (VIMS) arises from viewing moving scenes while stationary.
• VIMS is often preceded by vection (illusion of self-motion) and abnormal optokinetic nystagmus (OKN).
• Increased activity in the motion-sensitive middle temporal area (MT+) is implicated in VIMS, with prior studies suggesting right-hemispheric dominance.

Purpose of the Study:

• To investigate the role of inter-hemispheric synchronization in the human middle temporal area (MT+) during VIMS.
• To determine if VIMS is associated with desynchronized activity between the left and right MT+ cortices.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Participants viewed both VIMS-free and VIMS-inducing movies in a controlled order.
• Temporal correlations between corresponding left and right visual cortices, including MT+, were analyzed.

Main Results:

• A significant reduction in inter-hemispheric correlation within MT+ was observed during VIMS-inducing movies in susceptible individuals.
• This reduction in synchronization was specific to MT+ and not found in other visual areas (V1, V2, V3, V3A, V7).
• Insusceptible individuals did not show significant inter-hemispheric differences in MT+ activity.

Conclusions:

• This study provides the first evidence linking asynchronous bilateral MT+ activation to VIMS.
• Desynchronization between left and right MT+ may underlie VIMS by reflecting hemispheric imbalances in networks controlling eye movements, vection, and posture.