Running, Fast and Slow: The Dorsal Striatum Sets the Cost of Movement During Foraging

During reward-oriented behaviors, animals -including humans- spontaneously adjust the speeds of their decisions and movements based on dynamically changing costs and benefits. The mechanisms constraining these adaptive modulations remain unclear, especially in freely moving animals. Here, we developed a naturalistic foraging task in which rats decided when and how fast to run across a motorized treadmill to collect rewards. Model-based analyses explained why decision and movement speeds were coupled or decoupled as rats adapted to changes in reward value or motor cost, respectively. Moreover, lesions of the dorsal striatum increased the animals sensitivity to motor cost, limiting their running speed in the most effortful conditions while sparing reward-related behavioral modulations. Altogether, our study describes how neuroeconomic constraints influence decision and movement speeds in foraging rats, and paves the way for a refined understanding of the role of the basal ganglia in motor control and decision-making.