Distinct Regions of the Striatum Underlying Effort, Movement Initiation, and Effort Discounting

The ventral striatum is believed to encode the subjective value of cost/benefit options; however, this effect has notably been absent during choices that involve physical effort. Prior work in freely-moving animals has revealed opposing striatal signals, with greater response to increasing effort demands and reduced responses to rewards requiring effort. Yet, the relationship between these conflicting signals remains unknown. Using fMRI with a naturalistic maze-navigation paradigm, we identified functionally-segregated regions within ventral striatum that separately encoded effort activation, movement initiation, and effort discounting of rewards. Additionally, activity in regions associated with effort activation and discounting oppositely predicted striatal encoding of effort during effort-based decision-making. Our results suggest that the dorsomedial region hitherto associated with action may instead represent the cost of effort, and raises fundamental questions regarding the interpretation of striatal “reward” signals in the context of effort demands. This has implications for uncovering the neural architecture underlying motivated behavior.