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Motor affordance for grasping a safety handle
D W McDannald1, M Mansour2, G Rydalch3
1Department of Kinesiology & Health Science, Utah State University, United States.
Neuroscience Letters
|June 2, 2018
Summary
Viewing a safety handle primes hand muscles for grasping, showing how vision automatically prepares the body for balance recovery. This rapid motor facilitation occurs even before a fall is detected.
Area of Science:
- Neuroscience
- Motor Control
- Human Factors
Background:
- Visual observation of objects can activate motor cortical networks, facilitating movement.
- This visual-motor coupling is crucial for reactive balance control, enabling targeted limb adjustments.
- Safety handles are commonly used to regain balance, suggesting a role for visual cues in motor preparation.
Purpose of the Study:
- To investigate if viewing a safety handle activates motor cortical networks.
- To test the hypothesis that visual access to a handle enhances corticospinal excitability in hand muscles.
- To determine the timing and specificity of this motor facilitation.
Main Methods:
- Transcranial magnetic stimulation (TMS) measured corticospinal excitability in hand muscles.
- Participants performed a seated reach-grasp task with vision controlled by liquid crystal lenses.
- TMS pulses were time-locked to visual access of a presented handle or a covered (no handle) condition.
Main Results:
- Rapid motor facilitation was observed in right hand muscles (First Dorsal Interosseus, Opponens Pollicus) 120 ms after viewing a handle.
- This facilitation was absent at earlier (80 ms) and later (160 ms) time points.
- A decrease in Abductor Digiti Minimi activity was noted when viewing the handle, suggesting selective muscle engagement.
Conclusions:
- Vision of a safety handle rapidly primes specific hand muscles for grasping, supporting the concept of affordances.
- This automatic motor preparation based on visual cues has implications for proactive balance recovery strategies.
- The findings highlight the brain's ability to anticipate and prepare motor actions based on environmental visual information.
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