Differential coding of uncertain reward in rat insular and orbitofrontal cortex

Area of Science:

• Neuroscience
• Decision-making research
• Computational psychiatry

Background:

• The anterior insular cortex (AIC) and orbitofrontal cortex (OFC) are crucial for decision-making under risk.
• Previous research has not investigated risk-related neural activity in the AIC.
• The role of the rodent OFC in conveying genuine risk signals remains debated.

Purpose of the Study:

• To investigate AIC and OFC neuronal activity in rats during risk-based decision-making.
• To determine how these brain regions encode reward, value, and risk signals.
• To differentiate the specific contributions of AIC and OFC to risk processing.

Main Methods:

• Electrophysiological recordings of AIC and OFC neuronal activity in rats.
• Rats were trained to respond to auditory cues predicting water rewards of varying probabilities.
• Analysis of neural signals associated with different reward probabilities and outcomes.

Main Results:

• Both AIC and OFC exhibited significant neural signals for reward, value, and risk, often coded together.
• OFC showed stronger and earlier value signals; some OFC neurons specifically responded to certain (100%) reward cues.
• AIC neurons displayed prolonged activity after negative outcomes, correlating with previously expected value.

Conclusions:

• The AIC and OFC differentially encode neural signals related to reward uncertainty.
• The OFC appears critical for encoding subjective value biased towards certainty and modulated by risk.
• The AIC may signal prolonged negative outcomes and disappointment, contributing to adaptive learning.