The motor functions of the basal ganglia.

The past 25 years have seen a resurgence of interest in the basal ganglia. In the 1980s, a series of studies yielded the now classic descriptions of basal ganglia connectivity and information flow that now dominates textbook descriptions. This was followed by the appearance of reward-based learning theories of corticostriatal function in which dopamine played a critical role in modulating corticostriatal connectivity. These advances have contributed enormously to our understanding of the basic principles of some of the circuits within these structures, and have dominated novel approaches to treatment of basal ganglia diseases. Yet even so, many of the common symptoms of Parkinson's disease or dystonia are incompletely understood, suggesting that these "dark basements of the brain" still harbor hidden secrets.