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Orienting the finger opposition space during prehension movements
G E Stelmach1, U Castiello, M Jeannerod
1Vision et Motricité, Institut National de la Santé et de la Recherche Médicale, U94, 16 Avenue Doyen Lépine 69500 Bron, France.
Journal of Motor Behavior
|June 1, 1994
Summary
Grasping objects involves wrist rotation (pronation) planning. Pronation is integrated into motor plans for natural prehension without altering movement speed or smoothness.
Area of Science:
- Biomechanics
- Motor Control
- Human Factors Engineering
Background:
- Prehension, the act of grasping, is a fundamental human motor skill.
- Object orientation significantly influences grasp strategies and motor planning.
Purpose of the Study:
- To investigate the role of wrist pronation in prehension across different object orientations.
- To examine the kinematic effects of incorporating pronation into planned versus perturbed grasps.
Main Methods:
- Experiment 1: Determined thumb and index finger pad opposition preferences for objects at various orientations.
- Experiment 2: Analyzed wrist and elbow kinematics during prehension movements, comparing planned vs. perturbed pronation.
Main Results:
- Wrist pronation was used for object orientations of 110 degrees or greater.
- No kinematic differences were found in planned pronation grasps.
- Perturbed grasps requiring unexpected pronation increased movement time and deceleration duration.
Conclusions:
- Wrist pronation is pre-planned in natural prehension without kinematic cost.
- Motor execution is affected when pronation is unexpectedly required due to task perturbations.