Functional MR imaging in the study of working memory of frontal-parietal lobe in children

Objective:To investigate the relationship between activity of fronto-parietal lobe cortex in working memory task and the fibrous tract anisotropy of white matter in the same region of normal children with blood oxygen leve-dependent functional MRI(BOLD fMRI) and diffusion tensor imaging(DTI) techniques.Methods:Twelve healthy children volunteers(6 males,6 females,mean age 11.4 years) were recruited.Paced visual serial addition test(PVSAT) was used as the mode of stimulation,BOLD fMRI was performed in all 12 children to obtain the activated map;DTI was performed in the same location and thickness to assess the FA map.Regions of interest(ROIs) in white matter of left fronto-parietal lobes were selected and the overlapped images of the two above-mentioned maps and FA values were calculated.FA values in various regions and number of voxels activated in dorso-lateral prefrontal cortex(DLPFC) were calculated and statistically analyzed.Results:The fronto-parietal cortex was the main activated region by working memory task,including bilateral inferior parietal lobe(BA 40 region),bilateral inferior frontal gyrus(BA44 and 45 region).The activated region and the number of voxel were larger and more in dominant hemisphere(left) than that in the contralateral side.Overlapping activated maps of brain upon the FA maps showed that the activated voxels were almost exclusively located in regions of low anisotropy.Correlation was found between FA values of fronto-parietal white matter and activated regions in left DLPFC(r=0.822,P=0.001).Conclusion:BOLD fMRI in combination with DTI are helpful in the study of the relation between functional changes and anatomic structures during the process of working memory task in children.