Interlimb differences in coordination of unsupported reaching movements.

Area of Science:

• Neuroscience
• Motor Control
• Biomechanics

Background:

• Handedness is associated with interlimb coordination differences, potentially due to hemispheric specialization.
• Previous research, primarily on 2D tasks, proposed dominant hemisphere control of limb dynamics and non-dominant hemisphere control of limb impedance.

Purpose of the Study:

• To investigate interlimb differences in the control of unsupported 3D reaching movements.
• To examine how redundant degrees of freedom influence reaching control in dominant and non-dominant arms.

Main Methods:

• Participants performed unsupported 3D reaching movements in the horizontal plane with redundant vertical axis motion.
• Analysis focused on initial direction accuracy, final position accuracy, and movement along redundant axes.

Main Results:

• The dominant arm demonstrated superior accuracy and greater excursion along a redundant axis perpendicular to the task plane.
• The non-dominant arm showed better impedance control, impeding motion out of the task plane, but exhibited greater error variability.
• Non-dominant arm errors were significantly influenced by shoulder rotation, unlike dominant arm errors.

Conclusions:

• Findings support specialized control: dominant hemisphere for intersegmental coordination and non-dominant for impedance control.
• The dominant arm effectively utilized redundant degrees of freedom, while the non-dominant arm's control was constrained.
• Results contrast with planar task findings, suggesting task dimensionality impacts observed interlimb control strategies.