Temporal Dynamics Underlying Prelimbic Prefrontal Cortical Regulation of Action Selection and Outcome Evaluation...

Area of Science:

• Neuroscience
• Decision Science
• Behavioral Economics

Background:

• Risk/reward decision-making involves deliberation, action selection, and outcome evaluation.
• The prelimbic (PL) cortex is crucial for updating decision biases based on changing reward probabilities.
• The precise role of phasic PL signals during specific decision phases remains unclear.

Purpose of the Study:

• To investigate how temporally specific optogenetic inhibition of PL cortex activity influences choice behavior during different phases of risk/reward decision-making.
• To examine the impact of disrupting PL signals during action selection and outcome evaluation on choice biases and outcome integration.

Main Methods:

• Utilized optogenetic inhibition (eArchT) in male rats trained on a probabilistic discounting task.
• Temporally controlled light pulses selectively suppressed PL excitatory neuron activity before choice or after specific reward outcomes (large/small reward receipt, risky losses).
• Assessed changes in choice bias towards certain vs. risky rewards and the influence of recent outcomes on subsequent choices.

Main Results:

• Prechoice PL inhibition reduced bias towards preferred options and disrupted outcome-based choice updating.
• Inhibition during risky losses modulated the impact of reward omissions, depending on the risky option's profitability.
• Inhibition during reward receipt decreased risky choice when the risky option was more profitable, suggesting a value comparison role.

Conclusions:

• The PL cortex exhibits multifaceted contributions to decision-making, including implementing choice policies and integrating action-outcome feedback.
• PL signals dynamically assign context to the decision space, influencing both action selection and the evaluation of reward outcomes.
• These findings offer novel insights into the neural mechanisms underlying decision-making under reward uncertainty.