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

Abstract

Humans and other animals adjust when and how fast they execute goal-directed actions according to expected costs and benefits. Yet, the behavioral principles and brain regions underlying adaptive vigor control remain poorly understood. Here, we developed a self-paced foraging task in which rats must run across a motorized treadmill to collect rewards, allowing separate manipulation of benefit (reward delivery probability) and cost (effort). Throughout the foraging sessions, run timing and speed jointly reflected the rats idiosyncratic urgency to obtain rewards. In contrast, when the cost of crossing the treadmill increased, rats ran faster to maintain a high reward rate while run timing remained stable. Consistent with distinct mechanisms for adapting to costs or benefits, dorsal striatum lesions primarily limited running speed under effortful conditions, whereas ventral striatum lesions reduced rewardseeking urgency at session onset. Together, these findings suggest that vigor is modulated by costs and benefits through distinct striatal circuits.