RIGHT-HEMISPHERE SPEECH-PERCEPTION REVEALED BY AMOBARBITAL INJECTION AND ELECTRICAL INTERFERENCE

Objective: To investigate the right hemispheric speech perception capa bilities of an adult right-handed patient with seizures. Methods: Cons ecutive, unilateral, intracarotid sodium amobarbital injections and le ft hemispheric electrical interference mapping were used to determine lateralization and localization of speech perception, measured as syll able discrimination. Results: Syllable discrimination remained intact after lek and right intracarotid sodium amobarbital injections. Langua ge otherwise strongly lateralized to the left hemisphere. Despite evid ence of bilateral speech perception capabilities, electrical interfere nce testing in the left, posterior temporal lobe impaired syllable dis crimination. Conclusions: The results suggest a functionally symmetric , parallel system in the adult brain with preferential use of left hem ispheric pathways for speech perception.