Modulation of neural activity in frontopolar cortex drives reward-based motor learning

Area of Science:

• Neuroscience
• Cognitive Science
• Motor Control

Background:

• The frontopolar cortex (FPC) is involved in evaluating choice outcomes and reliability.
• Its role in motor learning, particularly with continuous reward gradients, is not well understood.

Purpose of the Study:

• To investigate the role of the right frontopolar cortex (FPC) in reward-based motor learning using transcranial direct current stimulation (tDCS).
• To examine how modulating FPC activity affects motor variability, exploration, and exploitation during learning.

Main Methods:

• Nineteen healthy participants learned novel finger movement sequences on a digital piano with auditory reward feedback.
• Anodal transcranial direct current stimulation (tDCS) was applied over the right FPC, left motor cortex (lM1), or sham.
• Bayesian computational modeling analyzed trialwise reward expectation, exploitation, exploration, and reward volatility.

Main Results:

• Right FPC-tDCS significantly accelerated motor learning compared to lM1-tDCS and sham, primarily by regulating motor variability.
• While all stimulation types showed increased exploitation following higher reward expectations, this link was weaker with lM1-tDCS.
• Frontopolar stimulation uniquely increased motor exploration's sensitivity to inferred changes in reward tendency (volatility).

Conclusions:

• Anodal tDCS over the right FPC enhances reward-based motor learning.
• Right FPC stimulation optimizes motor exploration by increasing sensitivity to reward volatility, leading to faster learning.
• These findings differentiate the FPC's role from motor cortex control in reward-guided motor adaptation.