Increased muscle coactivation is linked with fast feedback control when reaching in unpredictable visual environments

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Humans adapt to unpredictable disturbances by increasing movement velocity, muscle coactivation, and sensory feedback responses.
• Muscle coactivation's role in sensory feedback processing, beyond mere stiffness enhancement, is under investigation.

Purpose of the Study:

• To investigate how healthy participants adjust reaching movements and sensory feedback responses under variable visuomotor rotations.
• To test the hypothesis that muscle coactivation facilitates sensory feedback responses, rather than solely increasing limb stiffness.

Main Methods:

• Participants performed reaching movements under unpredictable visuomotor rotations with varying amplitude and direction.
• Key metrics measured included movement peak velocity, muscle coactivation levels, and responses to visual and proprioceptive feedback.

Main Results:

• Increased variability in visuomotor rotations led to higher movement peak velocity.
• Muscle coactivation levels and responses to sensory feedback (visual and proprioceptive) were significantly enhanced.
• The study observed a heightened neural responsiveness to sensory feedback.

Conclusions:

• Muscle coactivation appears to prime the nervous system for rapid sensory feedback processing.
• These adaptations help accommodate the demands of unpredictable visual environments during motor tasks.
• Findings suggest a more dynamic role for muscle coactivation in sensorimotor control.