FUNCTIONAL LATERALIZATION OF SPEECH PRODUCTION AT PRIMARY MOTOR CORTEX - A FMRI STUDY

TO evaluate lateralization of speech production at the level of the Ro landic cortex, functional magnetic resonance imaging (1.5 Tesla, 27 pa rallel axial slices, EPI-technique) was performed during a speech task (continuous silent recitation of the names of the months of the year) . As control conditions, non-speech tongue movements and silent singin g of a well-known melody with the syllable 'la' as its carrier were co nsidered. Tongue movements produced symmetrical activation at the lowe r primary motor cortex. During automatic speech a strong functional la teralization to the left hemisphere emerged within the same area. In c ontrast, singing yielded a predominant right-sided activation of the R olandic region. Functional lateralization of speech production therefo re seems to include the precentral gyrus as well as Broca's area.