CORTICAL SPEECH PROCESSING MECHANISMS WHILE VOCALIZING VISUALLY PRESENTED LANGUAGES

TO elucidate cortical processing during vocalization, we used positron emission tomography to measure regional cerebral blood flow during vo calization in six Japanese subjects. During reading Japanese sentences used daily or short syllables aloud, the visual cortices, the left He schl's gyrus, Broca's area, the primary motor area of the articulatory organs, the supplementary motor area and the cerebellum were signific antly activated, compared with resting conditions. The superior tempor al gyri were rarely activated. Significant activation of the cerebellu m was observed by comparing cortical activity during reading sentences used daily with that during reading meaningless short syllables. Thes e results suggest that vocalization of familiar materials is taken ove r by the cerebellum, rather than cortical speech areas, and without en gagement of the superior temporal gyri.