Contrasting Roles for Orbitofrontal Cortex and Amygdala in Credit Assignment and Learning in Macaques

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Decision Neuroscience

Background:

• The roles of the orbitofrontal cortex (OFC) and amygdala in flexible reward-guided behavior are debated.
• Previous research has not fully elucidated their distinct contributions to adaptive decision-making and credit assignment.

Purpose of the Study:

• To investigate the specific contributions of the lateral OFC (lOFC) and amygdala to flexible behavior and reward credit assignment.
• To examine the neural mechanisms underlying adaptive win-stay/lose-shift strategies.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to record brain activity in macaques performing an object discrimination reversal task.
• A probabilistic learning task was employed in a second experiment to confirm findings.
• Analysis focused on activity patterns and functional coupling between the lOFC and amygdala.

Main Results:

• A specific region in the lateral OFC (lOFC) showed activity predicting win-stay/lose-shift behavior.
• Amygdala and lOFC activity coupling increased during lose-shift trials.
• Coupling strength was modulated by reward information relevance, suggesting a role in credit assignment.
• Day-to-day performance fluctuations correlated with neural signal and coupling variations.

Conclusions:

• The OFC and amygdala make unique, complementary contributions to flexible behavior.
• The lOFC is involved in adaptive behavioral adjustments, while the amygdala processes reward information, including irrelevant cues.
• These findings refine our understanding of the neural basis of decision-making and credit assignment.