Functional MRI Study On Expressive Language Centers

[Objective]Functional MRI were performed on middle and old aged subjects with category-member generation and verb generation tasks to detect brain areas related to expressive language,especially those areas activated in both tasks.The main purpose was to supply normal control for functional MRI study on expressive aphasia.[Subjects and Methods]Twenty-three middle or old aged subjects were recruited in this study,all them received block-designed fMRI with Category-member generation and Verb generation tasks.The subjects were asked to imagine the words which belong to the category word showed to them during the Category-member task, and to generate a verb based on a given noun word during Verb generation task.GE 1.5T Twin speed MR Scanner was used to obtain fMRI data with GRE-EPI sequence (TR/TE,2500/60ms;FOV,24cm;Matrix,64×64;thickness,5mm;interslices gap, 1mm;slices,22).One hundred and forty nine phases and 119 phases were scanned in Category-member generation and Verb generation tasks respectively.SPM2 was used to process fMRI data.Pre-processing include realign,normalization and smooth. Group analysis was performed with single sample t-test.Finally,activated mapping was overlapped onto standard MNI template.Locations,MNI coordinate and activated intensity of the brain areas were recorded.[Results]Twelve subjects were recruited in the Category-member task and eleven in Verb generation task after affected factors(head motion,behavioral performance and machine noise)were ruled out.Activated regions in Category-member task include Broca's area,bilateral insular lobes,bilateral premotor cortex(PMC)with left prominence,bilateral supplemental motor area(SMA),left posterior parietal cortex,bilateral anterior cingulates,bilateral basal ganglions,left thalamus,and right cerebellum.Verb generation task mainly activated Broca's area,bilateral PMC and SMA, bilateral insular lobes,anterior part of the left cingulated gyrus,left posterior parietal cortex,bilateral thalamus and basal ganglions,bilateral cerebellum with right prominence,and bilateral occipital lobes.Brain regions activated in both tasks included Broca's areas,left insular lobes, bilateral PMC with left prominence and SMA,left posterior parietal cortex,left basal ganglion,left anterior cingulated gyrus,left thalamus,and right cerebellum.[Conclusion]Category-member and Verb generation were effective tasks for detecting brain areas related to expressive language with functional MRI.Combination of two tasks could improve the specificity for detecting expressive language areas.Expressive language areas formed a complex neural network which includes Broca's area,SMA,PMC,insular lobe,basal ganglion,thalamus,left cingulated gyrus,and right cerebellum.Lateralization of the expressive language areas presented with left hemisphere and right cerebellum prominence.