Reorganization of Cortical Language Areas in Patients with Aphasia: A Functional MRI Study

The purpose of this study is to delineate the pattern of reorganization of cortical language areas using functional magnetic resonance imaging (fMRI) after rehabilitation therapy in patients with aphasia. Six right-handed aphasic patients were investigated. Causes of aphasia were intracerebral hemorrhages of the left basal ganglia in 3 patients, cerebral infarction of the left MCA in 2, and surgical resection of the frontotemporal lobes to control intractable epilepsy in 1. An auditory sentence completion task was used to activate brain language areas during the fMRI. Three patients with left frontal lesions showed activation in the right inferior frontal lobes while performing language tasks, whereas the other 3, whose lesions located at subcortical areas, showed activation in the bilateral frontal and temporal lobes. Our results demonstrated the differences in interhemispheric reorganization of the language network depending on the location of the lesion in aphasic patients. While the patients with subcortical lesion showed tendency of bilateral frontal activation, those with cortical lesion showed activation of the right frontal lobe.

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

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.

A Functional MRI Study of Brain Language Network in Korean Adult

OBJECTIVES: To report the results of functional magnetic resonance imaging (fMRI) experiment to delineate brain network for auditory language tasks in normal Korean adults. METHOD: Five normal right-handed Korean males, aged 20~33 years, were investigated using fMRI technique. Language tasks consisted of auditory listening and verb generation tasks. In fMRI, twenty slices were obtained for each functional volume using single shot echoplanar image sequences. Eighty-four volumes were obtained for each functional run. Data were motion corrected, coregistered, normalized, and statistically analyzed using SPM-96 software (Wellcom Department of Cognitive Neurology, Oxford, UK). RESULTS: Functional activation were detected in superior temporal region (coordinates: x= 64, y= 42, z=2) in the left side and superior to middle temporal lobe (coordinates: x=50, y= 20, z=2) in the right side for auditory listening task. Auditory verb generation task activated inferior frontal gyrus (coordinates: x= 56, y=16, z=14), superior temporal region, and medial frontal region in the left side. Right temporal lobe was also activated in the superior to middle temporal areas. Activation was more extensive in the left side for both language tasks. CONCLUSION: Our results can remarkably delineate cortical and subcortical regions subserved for auditory language processing. These results can be contributing to understand the underlying mechanism of language disorders in brain-injured patients and to investigate the pattern of reorganization of language network after rehabilitation.