Brain Language Network and Lateralization Using for Spoken and Written Korean Words in Normal Adults: A Functional MRI Study

ABSTRACT

OBJECTIVE: This study involves an experiment using functional magnetic resonance imaging (fMRI) to delineate neural network and laterality of language related brain activation for spoken and written Korean words in normal adults. METHOD: Eight normal right-handed Korean males, aged 20~33 years, were investigated. Language tasks consisted of auditory and visual verb generation tasks. In fMRI, twenty slices were obtained for each functional volume using single shot echoplanar image sequences. Data were motion corrected, coregistered, normalized, and statistically analyzed using SPM-96 software. The number of activated voxels were counted in each hemisphere to calculate the laterality index according to each language task. RESULTS: In auditory verb generation task, inferior frontal gyrus and superior temporal region were activated in the left side. Right temporal lobe was also activated in the superior and middle temporal areas. Other activated area included medial frontal lobe. Lateralization index of auditory verb generation task was +78.6 +/-30.7. In visual verb generation task, inferior frontal gyrus was activated in the left side. Medial frontal lobe, both lateral occipital lobe, and left parietal lobe were also activated. The laterality index was +87.6 +/- 10.1. CONCLUSION: We could delineate cortical regions subserved for spoken and written Korean language and laterality of language related brain activation using fMRI. These results can contribute to understand underlying mechanism of language disorders in brain injury patients and to investigate the pattern of reorganization of language network after rehabilitation.