Disruption of automatic speech following a right basal ganglia lesion.

Following a right basal ganglia lesion, a right-handed man, age 75, was unable to recite familiar verses. Serial automatic speech, singing, recitation of rhymes, and swearing were impaired, and only idioms and social greetings were preserved. Speech no longer contained overused phrases and he could comprehend automatic speech. In contrast, propositional speech was preserved in both French and Hebrew. Right basal ganglia lesions may impair production but not comprehension of automatic speech.