Short-Term Sensorimotor Deprivation Impacts Feedforward and Feedback Processes of Motor Control

Area of Science:

• Neuroscience
• Motor Control
• Biomechanics

Background:

• Sensory loss causes irreversible neural and behavioral changes.
• Short-term limb immobilization models limb use deprivation, impacting proprioception and motor commands.
• Previous studies indicate immobilization causes motor control impairments, but the underlying mechanisms remain unclear.

Purpose of the Study:

• To investigate whether feedforward and/or feedback motor control processes are affected by short-term limb immobilization.
• To analyze kinematic changes during a Fitts' pointing task to understand motor control modifications.

Main Methods:

• Participants performed a Fitts' pointing task over two days.
• One group wore a splint for 24-hour limb immobilization.
• Kinematic analyses assessed movement speed, accuracy, and spatiotemporal structure.

Main Results:

• Immobilization resulted in a global slowdown of pointing movements.
• Both acceleration and deceleration phases were prolonged, indicating impacts on early and late movement phases.
• Altered movement structure suggests impaired feedforward (sensorimotor expectations) and feedback (proprioceptive processing) control.

Conclusions:

• Short-term immobilization alters motor control by affecting both predictive feedforward and corrective feedback mechanisms.
• Reduced efficiency in feedforward control may stem from an updated internal limb model.
• Increased movement time suggests altered proprioceptive feedback processing for online corrections.