Glossary
Dorsal striatum
What is the dorsal striatum?
The dorsal striatum is a group of structures beneath the cerebral cortex involved in choosing actions and learning. It contains circuits associated with both goal-directed and habitual behavior.
How it works
Yin and Knowlton distinguish dorsomedial, associative circuits from dorsolateral, sensorimotor circuits. This matters because the dorsal striatum is often described as a single habit system. Its different circuits support different forms of control.
In the rodent experiments reviewed, the dorsomedial striatum supported goal-directed control: actions adjusted when a reward lost value or no longer depended on the action. The dorsolateral striatum supported habitual control: responding could continue despite those changes. Disrupting these regions produced different effects, which is stronger evidence for the distinction than simply observing activity during a familiar movement.
Dopamine input from the substantia nigra pars compacta helps regulate striatal circuits. The review describes dopamine-dependent changes in synaptic strength—the connections through which neurons influence one another—as relevant to learning. The cellular processes differ across striatal regions; dopamine is not a single switch that turns an intention into a habit.
Repetition can favor habitual control under some conditions. These findings come from defined experimental tasks, with much of the causal evidence from rats, so they do not establish which circuit controls a particular person's everyday routine.
Why it matters
Driving your usual route when you meant to go somewhere else is a familiar action slip. To study habitual control experimentally, researchers ask a more specific question: does the action persist when its outcome loses value or its relationship to that outcome changes? A routine, or a fluent performance, does not answer that question by itself.