ROLE OF MOUSE DORSOMEDIAL FRONTAL CORTEX IN MODULATING VIGOR AND MAINTENANCE OF GOAL-DIRECTED LOCOMOTION

Goal-directed behavior often imposes dual requirements: the internal drive to initiate action, and the reactive control to adjust the ongoing action based on sensory feedback and reward information. While the dorsomedial frontal cortex (dmFC) supports motor planning, it remains unclear how the region represents these contrasting demands within the same task structure. We trained mice on a head-fixed task requiring a self-initiated run of variable duration (1–2s) followed by an auditory cue requiring speed-threshold maintenance for reward. To decompose performance, we derived two metrics: initiation vigor (IV), based on pre-cue peak speed, and cue maintenance (CM), based on time spent above trial failure threshold during the cue period. Behavioral analysis showed that while IV determined the magnitude of locomotion, trial success depended on CM. Expert mice performed trials with high IV and sufficient CM to obtain rewards consistently. Pharmacological inactivation with muscimol reduced the number of self-initiated trials and lowered both metrics, confirming dmFC’s role in both the initial decision to act and the speed regulation required after the cue. Using tetrode recordings in M2 and ACC, we analyzed population-level dynamics via time-resolved Euclidean distance. This revealed a clear temporal dissociation: neural trajectories exhibited significant separation based on IV during the self-timed preparatory phase, whereas separation related to CM and trial outcome peaked only after the sensory cue. These results indicate that the dmFC supports goal-directed behavior by engaging distinct populations to promote the control of voluntary initiation and maintenance of goal-directed locomotion.