Effects of left basal ganglia lesions on language production.

Three patients with lesions mainly confined to the left basal ganglia were studied with a series of neuropsychological and neurolinguistic tests. Two patients were nonfluent, whereas one presented with fluent spontaneous speech. All of them produced agrammatic sentences and lexical and semantic mistakes. Perserverations and echolalias were two further characteristic disorders of their speech production. The linguistic symptoms observed in these three patients suggest that the left basal ganglia play an important role (a) in regulating arousal and speech initiation, (b) in monitoring the semantic and lexical aspects of language, and (c) in switching from one linguistic element to the following during language production.