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Exploring the role of reduced optic flow in dynamic balance
Nora Pourhashemi1, Taylor W Cleworth1
1School of Kinesiology and Health Sciences, York University, Toronto, ON, Canada; Centre for Vision Research, York University, Toronto, ON, Canada.
Gait & Posture
|February 19, 2025
Summary
Sway increases when optic flow is reduced, but half the normal amount is sufficient for stable balance. This highlights vision's crucial role in dynamic postural control.
Area of Science:
- Human movement science
- Neuroscience
- Vision science
Background:
- Reduced optic flow amplifies postural sway.
- Limited research exists on the minimum optic flow needed for stable balance during dynamic tasks.
Purpose of the Study:
- To investigate the impact of reduced optic flow on postural sway during dynamic stance.
- To determine the threshold of optic flow required to maintain baseline postural sway.
Main Methods:
- Twenty-six healthy adults stood on a force plate and experienced platform translations.
- Virtual reality was used to manipulate optic flow gain relative to head motion.
- Centre of Pressure (COP) and Head Position (HeadPos) data were analyzed for amplitude and mean power.
Main Results:
- Increased COP and HeadPos amplitude were observed when optic flow gain was below 0.5x.
- The Medium frequency band (0.1-0.5 Hz) of mean power also increased with reduced optic flow.
Conclusions:
- Approximately 50% of normal optic flow is sufficient to maintain postural sway comparable to real-world conditions (gain of 1).
- Visual input is critical for dynamic balance, influencing frequencies beyond those typically considered in quiet stance.
