Transient inactivation of orbitofrontal cortex blocks reinforcer devaluation in macaques

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Primate Cognition

Background:

• The orbitofrontal cortex (OFC) and basolateral amygdala (BLA) are vital for goal-directed behaviors, particularly adapting to altered reward values.
• Understanding the distinct roles of OFC and BLA in processing reward information is crucial for deciphering decision-making processes.

Purpose of the Study:

• To investigate the specific contribution of the OFC to adaptive behavior using a reinforcer devaluation paradigm in macaques.
• To differentiate the functional roles of the OFC and BLA in conditioned reinforcer devaluation.

Main Methods:

• Employed a reinforcer devaluation paradigm with four macaques, associating objects with primary food reinforcers.
• Utilized transient inactivation of the OFC (area 13) via muscimol infusion during different phases of the devaluation task.
• Monitored behavioral choices of macaques when presented with objects linked to devalued versus non-devalued food rewards.

Main Results:

• Macaques normally exhibited a devaluation effect, shifting choices away from objects associated with devalued rewards.
• Transient inactivation of the OFC significantly blocked this devaluation effect, with monkeys failing to reduce choices for devalued items.
• OFC inactivation was effective when occurring during satiety and choice, or during the choice phase alone, indicating its necessity for guiding post-satiety choices.

Conclusions:

• OFC activity is essential during the post-satiety choice period for guiding object selection based on updated reward values.
• The OFC plays a distinct role compared to the BLA in the conditioned reinforcer devaluation process, with OFC being critical for choice guidance.
• These findings demonstrate that OFC inactivation is sufficient to impair devaluation-guided behavior, clarifying its unique contribution to adaptive decision-making.