Opioid Modulation of Value-Based Decision-Making in Healthy Humans

Area of Science:

• Neuroscience
• Decision-making research
• Pharmacology

Background:

• The μ-opioid receptor (MOR) system is known to regulate motivation and reward preference in rodents.
• The specific role of human MORs in value-based decision-making remains largely uncharacterized.
• Understanding MOR involvement is crucial for comprehending adaptive behaviors and reward processing.

Purpose of the Study:

• To investigate the contribution of the human MOR system to value-based decision-making.
• To determine if MOR agonists and antagonists have opposing effects on decision processes.
• To elucidate how MORs modulate the bias towards high-reward options.

Main Methods:

• A double-blind, placebo-controlled, cross-over study involving 30 healthy men.
• Administration of morphine (10 mg), naltrexone (50 mg), and placebo.
• Participants completed a two-alternative forced-choice task measuring decision bias.
• Drift-diffusion model (DDM) analysis of accuracy and reaction time data.

Main Results:

• Morphine (MOR agonist) increased preference for high-reward probability stimuli (starting point shift).
• Morphine increased, and naltrexone (MOR antagonist) decreased, the efficiency of evidence accumulation.
• No significant effects were observed on motor coordination, speed-accuracy trade-off, or subjective state.

Conclusions:

• The human MOR system plays a significant role in value-based choice.
• MOR modulation influences decision-making by adjusting effort and tuning choices towards high-value rewards.
• These findings provide insights into the neural mechanisms underlying adaptive decision-making.