The role of basal ganglia in language production: evidence from Parkinson's disease.

According to the dominant view in the literature, basal ganglia do not play a direct role in language but are involved in cognitive control required by linguistic and non-linguistic processing. In Parkinson's disease, basal ganglia impairment leads to motor symptoms and language deficits; those affecting the production of verbs have been frequently explored. According to a controversial theory, basal ganglia play a specific role in the conjugation of regular verbs as compared to irregular verbs. We report the results of 15 patients with Parkinson's disease in experimental conjugation tasks. They performed below healthy controls but their performance did not differ for regular and irregular verbs. These results confirm that basal ganglia are involved in language processing but do not play a specific role in verb production.