1) Dopamine transmission in the basal ganglia controls motor behavior through two pathways - the direct pathway which stimulates motion, and the indirect pathway which inhibits motion. 2) CK1δ over-expression disrupts this system, possibly through dopamine deficiency caused by downregulation of D1 and D2 receptors. 3) This study found an increase in calretinin-containing neurons in the striatum of CK1δ over-expressing mice, suggesting this imbalance contributes to their ADHD-like behaviors.