Orbitofrontal cortical neurons encode expectation-driven initiation of reward-seeking

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Decision Making

Background:

• Adaptive behavior relies on frontal cortical areas for execution and inhibition.
• Medial prefrontal cortex is studied for context-dependent behavior, but orbitofrontal cortex (OFC) roles in response execution/inhibition, especially during extinction learning, are unclear.
• OFC is crucial for reward-guided behavior, yet its neuronal activity during response initiation and inhibition remains poorly understood.

Purpose of the Study:

• To characterize orbitofrontal cortex (OFC) neuronal activity during reward-seeking behavior and extinction learning.
• To investigate the relationship between OFC neural activity and the initiation versus inhibition of responses.
• To determine if OFC activity tracks reward-predicting cues or context-guided response inhibition.

Main Methods:

• Recorded neuronal activity from the orbitofrontal cortex (OFC) in rats.
• Rats performed a discriminative-stimulus (DS)-driven sucrose-seeking task.
• Subsequent extinction phases involved withholding sucrose despite the DS.

Main Results:

• OFC neuronal activity peaked during the initiation of reward-seeking actions, specifically lever pressing and approaching the reward well.
• Activity was strongest when reward-predicting stimuli (RS) reliably predicted sucrose, and weak during nonrewarded stimuli (NS) or extinction.
• OFC neurons shifted selectivity to track rewarded behaviors when cue-outcome contingencies were reversed, but did not show strong signals for response inhibition or extinction.

Conclusions:

• Orbitofrontal cortex (OFC) activity is primarily associated with the initiation of reward-seeking components, driven by predictive cues.
• OFC neuronal activity does not appear to signal extinction learning or response inhibition directly.
• The findings highlight OFC's role in driving motivated actions rather than suppressing them based on context.