Early versus optimal motor learning changes striatal DAT levels. DAT-regulated activation of the D1 pathway in the dorsolateral striatum, during early-stage of incremental motor learning, cooperates with D1 pathway activation to prevent premature shifting to habit learning. Overexpression of α-syn impairs motor learning by altering DAT expression, before leading to DA neuronal loss and bradykinesia. The gene discussed is SLC6A3; the disease is Bradykinesia.