Dynamic changes in representations of preceding and upcoming reward in monkey orbitofrontal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Decision Neuroscience

Background:

• The orbitofrontal cortex (OFC) plays a key role in adaptive behavior and decision-making.
• Understanding how neural representations within the OFC change with reward contingencies is essential for elucidating executive functions.

Purpose of the Study:

• To investigate the dynamic changes in orbitofrontal cortex (OFC) neuronal activity during a task with shifting reward schedules.
• To determine how OFC neurons encode reward information in different contexts and over time.

Main Methods:

• Recorded neuronal activity from monkey orbitofrontal cortex during a visually cued, multi-trial reward schedule task.
• Analyzed neuronal responses in relation to preceding reward, upcoming reward, reward delivery, and task schedule state.
• Examined reward representation by neuronal ensembles, considering context and temporal dynamics.

Main Results:

• A significant proportion of OFC neurons were sensitive to task events, with activity modulated by reward history, upcoming rewards, and schedule state.
• Upcoming reward-dependent activity was specific to the valid cue context, while preceding reward-dependent activity was present in both valid and random cue contexts.
• The representation of reward information evolved over time, with preceding reward signals decreasing and upcoming reward signals increasing as trials progressed.

Conclusions:

• Orbitofrontal cortex neuronal activity demonstrates contextual and temporal adaptability, reflecting the changing importance of reward information.
• This adaptable neural coding in the OFC is a fundamental mechanism supporting executive functions and flexible behavior.
• The findings highlight the OFC's critical role in updating reward representations to guide adaptive decision-making.