Reward-Dependent Selection of Feedback Gains Impacts Rapid Motor Decisions

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Sensorimotor control theories propose movement planning involves selecting goal-directed strategies.
• Understanding how reward influences these strategies, particularly feedback control, is crucial for advancing motor control research.

Purpose of the Study:

• To investigate the influence of target reward on feedback control mechanisms during human reaching movements.
• To explore how reward magnitude and differences across multiple goals affect rapid motor decisions and movement flexibility.

Main Methods:

• Three human reaching experiments were conducted.
• Explicit target rewards were manipulated to observe effects on feedback gains, movement vigor, and muscle activity.
• Perturbations were introduced to assess rapid motor decisions and goal switching strategies under varying reward conditions.

Main Results:

• Higher target rewards led to increased feedback gains, evidenced by greater velocities, enhanced responses to external loads, and elevated background muscle activity.
• Movement vigor, influenced by reward, affected goal switching; more vigorous movements were less likely to switch goals after perturbations.
• Biasing feedback gains via background load demonstrated a causal link, influencing target switch proportions and highlighting the interplay between muscle activity and decision-making.

Conclusions:

• Target reward significantly impacts feedback control, modulating movement vigor and influencing motor planning strategies.
• A competition exists between movement vigor, driven by reward, and behavioral flexibility, particularly in rapid motor decision-making.
• These findings provide insights into the neural mechanisms underlying reward-based adaptation in sensorimotor control.