Continuous contributions of the dorsolateral striatum to movement initiation and execution

Spikes in the dorsolateral striatum (DLS) of the basal ganglia correlate with forelimb and whole-body movements, but the extent to which they contribute to movement remains unclear. Using behavior-timed optogenetic inhibition in rats performing a lever-release task, we found that DLS inhibition delayed the initiation of forelimb reaching and conditioned lever release and, when delivered during reaching, interrupted execution. Inhibition during reward retrieval impaired locomotion, especially turning, reducing movement speed and resulting in less efficient trajectories. By contrast, inhibition before the nose poke that triggered reward delivery had little effect, despite substantial DLS activity at the nose poke. These effects were accompanied by bidirectional changes in firing rates in the substantia nigra pars reticulata, a basal ganglia output nucleus, and were much weaker when the dorsomedial striatum was perturbed. Together, these findings suggest that expression of many, but not all, learned movement patterns depends continuously on DLS activity.