Objective: To investigate the right hemispheric speech perception capabilities of an adult right-handed patient with seizures.
Methods: Consecutive, unilateral, intracarotid sodium amobarbital injections and left hemispheric electrical interference mapping were used to determine lateralization and localization of speech perception, measured as syllable discrimination.
Results: Syllable discrimination remained intact after left and right intracarotid sodium amobarbital injections. Language otherwise strongly lateralized to the left hemisphere. Despite evidence of bilateral speech perception capabilities, electrical interference testing in the left posterior temporal lobe impaired syllable discrimination.
Conclusions: The results suggest a functionally symmetric, parallel system in the adult brain with preferential use of left hemispheric pathways for speech perception.