Reinforcement and error feedback differentially impact motor exploration during locomotion.

Area of Science:

• Human motor control
• Biomechanics
• Neuroplasticity

Background:

• Reinforcement and error feedback are established drivers of motor learning and exploration in upper limb movements.
• Previous research indicates that unrewarded movements promote greater exploration, enabling the nervous system to refine actions based on movement variability.
• This study extends these findings to locomotion, examining feedback effects on walking and balance.

Purpose of the Study:

• To investigate the influence of reinforcement and error feedback on motor exploration during walking.
• To determine the impact of different feedback types on upright balance control.
• To compare motor exploration in walking to previously observed patterns in reaching tasks.

Main Methods:

• Twenty-four healthy young adults walked on an instrumented treadmill with virtual reality feedback on step length or width.
• Visual feedback indicated step parameters relative to a target zone; reinforcement feedback provided a reward for accuracy.
• Lag-1 autocorrelation and linear models of ankle roll and step placement were used to quantify exploration and balance strategies.

Main Results:

• Motor exploration increased with reinforcement feedback compared to error feedback for step length, but not step width.
• Error feedback promoted corrective behavior, leading to more precise step placement.
• Step width feedback altered balance control, making center of mass less predictive of ankle roll compared to baseline.

Conclusions:

• Step length regulation during walking responds to feedback similarly to upper limb reaching tasks.
• Maintaining upright balance during step width tasks necessitates reduced motor exploration.
• Feedback influences balance control mechanisms, highlighting a trade-off between exploration and stability.