Reward Maximization Assessed Using a Sequential Patch Depletion Task in a Large Sample of Heterogeneous Stock Rats

Area of Science:

• Behavioral neuroscience
• Animal behavior
• Decision-making

Background:

• Impulsive choice is typically assessed using delay discounting (DD), involving choices between immediate smaller or delayed larger rewards.
• This study explored reward maximization using a patch depletion model in a large cohort of Heterogeneous Stock (HS) rats.

Approach:

• A Sequential Patch Depletion procedure presented rats with concurrent choices between two water patches.
• Rats chose to 'stay' in a patch (decreasing rewards) or 'leave' for a delayed reset to maximum reward.
• Visit duration in a patch was analyzed as a potential analogue to the indifference point in DD tasks.

Key Points:

• While traditional delay discounting showed minimal sex differences, females exhibited distinct reward maximization behaviors.
• Females made fewer patch changes and spent longer in patches, resulting in a lower overall rate of reinforcement compared to males.
• Females showed a greater deviation from optimal choices, potentially leading to reduced reward intake.

Conclusions:

• Reward maximization measures, particularly via the patch depletion model, are more sensitive to sex differences in choice behavior than traditional delay discounting in HS rats.
• These findings suggest that reward maximization and delay discounting may involve distinct underlying neural or cognitive processes.
• The patch depletion model offers a valuable alternative for detecting subtle sex-based variations in decision-making strategies.