COMPREHENSION DEFICITS ELICITED BY ELECTRICAL-STIMULATION OF BROCA AREA

We report on three patients with intractable focal seizures arising fr om the language-dominant left hemisphere. In the work-up prior to surg ical treatment, arrays of subdural electrodes were placed over the lef t temporal lobe and adjacent supra-Sylvian region. Electrical stimulat ion of the inferior frontal cortex language region ('Broca's area') pr oduced marked interference with language output functions including sp eech arrest, slowing of oral reading, paraphasia and anomia. At some c ortical language sites in this region cortical stimulation also produc ed language comprehension deficits, particularly in response to more c omplex auditory verbal instructions and visual semantic material. The severe impairment of comprehension verbal information was in clear con trast with ability to process non-verbal material, which was not affec ted.