Implicit Sensorimotor Adaptation Proceeds in Absence of Movement Execution.

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Implicit sensorimotor adaptation involves adjusting movements based on sensory prediction errors (SPEs).
• Adaptation has been traditionally linked to motor command execution, but motor imagery (MI) also engages predictive mechanisms.
• The sufficiency of MI to drive implicit adaptation remains an open question.

Purpose of the Study:

• To investigate whether motor imagery (MI) is sufficient to induce implicit sensorimotor adaptation.
• To compare the effects of MI versus movement execution on adaptation.
• To explore adaptation mechanisms independent of explicit motor command generation.

Main Methods:

• A within-subject design with 30 human participants assessed implicit adaptation in a center-out reaching task.
• Conditions included: movement execution with visuomotor rotation, motor imagery with rotated visual feedback, and a control with visual feedback only, preventing MI.
• Post-rotation biases (PRBs) were measured to quantify adaptation.

Main Results:

• Both movement execution and motor imagery conditions resulted in significant directional biases.
• The magnitude of adaptation was significantly greater in the movement execution condition compared to motor imagery.
• Significant biases were also observed in the control condition, suggesting adaptation occurred without explicit MI.

Conclusions:

• Implicit sensorimotor adaptation can be partially driven by processes beyond direct motor command generation.
• Movement execution potentiates implicit adaptation, leading to larger effects than motor imagery alone.
• Adaptation may involve sensory prediction error processing that can be influenced by visual feedback even without active motor imagery or execution.