By using case studies of bilingual patients with cerebral lesions, researchers theorized that language switching relies on the inhibition of the non-target language using the left basal ganglia alongside executive control processes with the anterior cingulate, prefrontal, and front cortices, or bilateral supramarginal gyri and Broca's area. The dorsolateral prefrontal cortex has also been shown as significant in controlling language switching and inhibiting the unused language through observations of uncontrollable language switching in patients with damage to this brain area. Increased activation is seen in dorsolateral prefrontal cortex during language switching, but not regularly.