Different Control Strategies Drive Interlimb Differences in Performance and Adaptation during Reaching Movements in...

Area of Science:

• Motor control
• Human movement science
• Neuroscience

Background:

• Human motor control exhibits lateralization, with distinct arm preferences for movement tasks.
• Computational underpinnings of skilled movement and arm asymmetry remain unclear.
• Previous studies on arm control differences were confounded by group comparisons or inter-limb transfer.

Purpose of the Study:

• To investigate the computational differences in movement control between dominant and nondominant arms.
• To examine arm adaptation strategies in a reach task using a within-subject design.
• To clarify the roles of predictive and impedance control in motor lateralization.

Main Methods:

• Two experiments involving reach adaptation tasks with healthy volunteers.
• Randomized performance of left and right arm movements to minimize inter-limb transfer.
• Analysis of adaptation to force fields and feedback responses, including electromyography (EMG) data.

Main Results:

• Both arms demonstrated similar adaptation capabilities and performance levels.
• The nondominant arm showed initial slight performance deficits, but achieved comparable late-trial performance.
• The nondominant arm employed a robust, model-free control strategy during force field adaptation, distinct from the dominant arm.

Conclusions:

• Both arms can adapt movement control effectively within an optimal control framework.
• The nondominant arm's strategy is likely a compensation for less precise internal movement models.
• Differences in motor skill lateralization are not solely due to predictive or reactive control variations but involve strategic adaptations.