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How dependent are grip force and arm actions during holding an object?
1UMR 6559 Mouvement et Perception, Faculté des Sciences du Sport, Université de la Méditerranée, CNRS, 163 avenue de Luminy, 13288, Marseille, France. danion@laps.univ-mrs.fr
Experimental Brain Research
|March 12, 2004
Summary
The central nervous system tightly couples arm actions and grip force. This neural coupling, investigated through three tasks, can lead to unintended grip force adjustments during arm movements.
Area of Science:
- Neuroscience
- Biomechanics
- Motor Control
Background:
- Arm actions and precision grip force are typically coupled by the central nervous system during object manipulation.
- Understanding the extent and nature of this neural coupling is crucial for explaining motor control strategies.
Purpose of the Study:
- To investigate the neural coupling between arm actions and precision grip force.
- To determine if this coupling is unidirectional and task-dependent.
Main Methods:
- Eleven subjects performed three tasks designed to either promote or dissociate grip force and arm actions.
- Tasks involved manipulating a grasping device with varying load conditions and explicit grip force modulation instructions.
Main Results:
- Grip force adjustments closely followed arm actions in Task 1, suggesting a feedforward mechanism.
- In Task 2, grip force modulated even with constant load, mimicking Task 1 responses.
- Voluntary grip force changes did not affect arm actions in Task 3.
Conclusions:
- The neural coupling between arm actions and grip force can lead to suboptimal motor responses.
- This coupling is influenced by the primary task focus and appears to be unidirectional.