what regions of the brain the movements correlate to. It was found that "increasing movement extent was associated with parallel increases of rCBF in bilateral basal ganglia (BG; putamen and globus pallidus) and ipsilateral cerebellum." This not only shows that the putamen affects movement but it also shows that the putamen integrates with other structures in order to perform tasks. One study was done in order to specifically investigate how the basal ganglia influences the learning of sequential movements. Two monkeys were trained to press a series of buttons in sequence. The methods used were designed to be able to monitor the well-learned tasks versus the new tasks. Muscimol was injected into various parts of the basal ganglia, and it was found that "the learning of new sequences became deficient after injections in the anterior caudate and putamen, but not the middle-posterior putamen". This shows that different areas of the striatum are utilized when performing various aspects of the learning of sequential movements. Role in learning In many studies, it has become apparent that the putamen plays a role in many types of learning. Some examples are listed below: Reinforcement and implicit learning Along with various types of movement, the putamen also affects reinforcement learning and implicit learning. Reinforcement learning is interacting with the environment and catering actions to maximize the outcome. Implicit learning is a passive process where people are exposed to information and acquire knowledge through exposure. Although the exact mechanisms are not known, it is clear that dopamine and tonically active neurons play a key role here. Tonically active neurons are cholinergic interneurons that fire during the entire duration of the stimulus and fire at about 0.5–3 impulses per second. Phasic neurons are the opposite and only fire an action potential when movement occurs. Category learning One particular study used patients with focal lesions on the basal ganglia (specifically the putamen) due to stroke in order to study category learning. The advantage to using these types of patients is that dopaminergic projections to the prefrontal cortex are more likely to be intact. Also, in these patients, it is easier to relate specific brain structures to function because the lesion only occurs in a specific place. The goal of this study was to determine whether or not these lesions affect rule-based and information-integration task learning. Rule-based tasks are learned via hypothesis-testing dependent on working memory. Information-integration tasks are