Reward value coding distinct from risk attitude-related uncertainty coding in human reward systems

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Decision Neuroscience

Background:

• Human decision-making relies on evaluating expected value and uncertainty.
• Understanding the neural basis of these evaluations is crucial for explaining choice behavior.

Purpose of the Study:

• To differentiate brain activations associated with expected value (magnitude and probability) from uncertainty (variance) in monetary rewards.
• To investigate how individual risk attitudes modulate these neural responses.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to observe brain activity.
• Participants performed a behavioral task involving stimuli with varying expected values and uncertainty levels.

Main Results:

• Higher expected values correlated with increased striatal activation, independent of magnitude/probability combinations.
• Increased uncertainty (variance) led to greater activation in the lateral orbitofrontal cortex.
• Orbitofrontal cortex and prefrontal cortex activations showed differential covariation with uncertainty based on individual risk preferences.

Conclusions:

• The brain distinctly codes expected value and uncertainty in separate neural structures.
• Specific prefrontal regions are implicated in processing risk aversion and risk-seeking behaviors.
• These findings provide insights into the neural mechanisms underlying economic decision-making under risk.