Functional Mapping of Frontal Language Area by Electrical Stimulation

Abstract

    Electrical stimulation mapping studies in 2 patients with brain tumor showed the following functional localization in the frontal language area ; 1) Stimulation of the inferior part of the left precentral gyrus produced the same articulatory disturbance as anarthria (phonetic disintegration) developed by Broca's aphasics due to cerbro-vascular accidents. At some electrodes where anarthria occurred, we also demonstrated mild writing impairment consisting of literal paragraphia in Kana (phonogram) and difficulty in retrieving Kanji (ideogram) characters. 2 ) Stimulation of Broca's arera did not elicit anarthria but word finding difficulty with some phonemic cue effects or verbal paraphasias. At some electrodes in Broca's area, paragraphia in Kanji was also observed. 3 ) Stimulation of the foot of the second frontal gyrus, so called Exner's writing center, did not produce writing disturbance but word finding difficulty or verbal praraphasias.