Premotor and Motor Cortices Encode Reward.

Area of Science:

• Neuroscience
• Motor Control
• Decision Making

Background:

• Action-associated rewards are crucial for motivation and learning.
• Motor cortices (dorsal premotor cortex [PMd] and primary motor cortex [M1]) are involved in movement planning and execution.
• It remains unclear if motor cortices encode reward signals beyond limb kinematics and dynamics.

Purpose of the Study:

• To investigate the presence and nature of reward signals within the PMd and M1.
• To determine if motor cortex neurons encode reward information independently of movement parameters.

Main Methods:

• Neuronal recordings were performed in non-human primates during a task involving rewarded and unrewarded trials.
• Analysis focused on neuronal firing rates in PMd and M1.
• Statistical methods were used to differentiate reward signals from kinematic and other task-related confounds.

Main Results:

• A categorical reward signal was identified in PMd and M1 neurons.
• This signal manifested as increased firing rates during unrewarded trials, irrespective of reward expectation.
• The reward signal was shown to be independent of error magnitude, reward prediction error, and kinematic differences.

Conclusions:

• The motor cortex contains a distinct reward signal.
• This reward information is encoded independently of movement execution details.
• Findings are critical for understanding reward-based learning and motivational influences on motor actions.