Effect of Extrinsic Reward on Motor Plasticity during Skill Learning.

Area of Science:

• Neuroscience
• Motor Control
• Human Motor Learning

Background:

• Performance feedback enhances human motor skill acquisition.
• Extrinsic rewards, like money, can further improve skill learning, but the underlying neurophysiology is not well understood.

Purpose of the Study:

• To investigate the neurophysiological mechanisms by which monetary reward influences motor plasticity during skill learning.
• To assess the impact of reward on corticospinal excitability, inhibition, and use-dependent plasticity.

Main Methods:

• Sixty-five healthy participants performed a pinch-grip task under three conditions: sensory feedback only, sensory and reinforcement feedback, or feedback with monetary reward.
• Transcranial magnetic stimulation (TMS) was used to probe motor plasticity in the primary motor cortex at rest before, early during, and after training.
• Motor-evoked potentials were measured to assess corticospinal output amplitude and variability, GABAergic short-intracortical inhibition, and use-dependent plasticity.

Main Results:

• Monetary reward significantly accelerated motor skill learning compared to feedback alone.
• In the reward group, corticospinal output variability decreased early in training, an effect more pronounced in reward-sensitive individuals.
• Other measures of motor excitability and inhibition did not differ significantly across groups.

Conclusions:

• Monetary reward enhances motor skill learning by modulating resting-state corticospinal variability early in the learning process.
• Reward sensitivity plays a role in the neurophysiological benefits of extrinsic rewards on motor skill acquisition.
• Fine-tuning of corticospinal output variability is a key mechanism linking reward to improved motor learning.