Fatigue modulates dopamine availability and promotes flexible choice reversals during decision making

Area of Science:

• Neuroscience
• Behavioral Economics
• Animal Cognition

Background:

• Animals balance reward goals with effort expenditure during decision-making.
• The impact of physical exercise and fatigue on effort-based choices and neurochemistry is not fully understood.
• It remains unclear if fatigue affects flexible decision strategies or only action execution.

Purpose of the Study:

• To investigate how fatigue influences effort-based decision-making strategies in mice.
• To determine if fatigue impacts cost-benefit computations or post-decision processes.
• To explore the neurochemical correlates of fatigue-induced changes in choice behavior.

Main Methods:

• Mice were trained on a T-maze task with high-cost/high-reward and low-cost/low-reward options.
• Parametric fatigue was induced using treadmill exercise at varying workloads (e.g., 80% peak workload).
• Choice behavior and subcortical dopamine levels were monitored.

Main Results:

• Mice exhibited a sharp, temporary reversal in choice from high-reward to low-reward arms at 80% peak workload.
• This choice reversal demonstrated flexibility, as mice reverted to high-reward choices at lower workloads or with different task structures.
• Fatigued mice showed increased subcortical dopamine levels.

Conclusions:

• Fatigue can be flexibly incorporated into cost-benefit computations, enhancing foraging efficiency.
• The observed choice reversals indicate adaptive decision-making strategies in response to fatigue.
• Increased dopamine levels in fatigued mice may reflect a bias towards model-based control, similar to humans.