Activity in the dorsomedial striatum decreases with improvement in motor coordination

It is widely thought that during early stages of motor learning, the dorsomedial striatum facilitates the learning of goal-directed actions, and at later stages, the learned actions are transferred to the dorsolateral striatum, which enables motor actions to become a skill or habit. It is however unknown if these striatal regions are simultaneously active as expertise is acquired during practice. To address this question, we developed a treadmill task to track changes in mouse locomotor coordination during practice running at a range of speeds. We analyzed body position and paw movement to evaluate changes in motor coordination over practice using DeepLabCut and custom-built code. By simultaneous evaluation of motor coordination improvements and fiber photometry recordings of neuronal calcium activity during training, we found that direct pathway dorsomedial striatum neurons exhibited reduced activity as the mouse became proficient at running on the treadmill. In contrast, direct pathway activity in dorsolateral striatum was similar throughout training and did not correlate with increased skill proficiency. These results provide new tools to measure changes in fine motor skills during simultaneous recordings of brain activity, revealing fundamental features of the neural substrates of motor learning. ### Competing Interest Statement The authors have declared no competing interest.