Combined Study of fMRI and DTI for Working Memory of Adults

Aim:To explore whether there is relation between brain activity of working memory and anisotropy of the fronto-parietal white matter in adults by combining fMRI and DTI.Methods:16 healthy adults aged 21～24 years were investigated.Brain activity of working memory was measured by using the blood oxygen level-dependent(BOLD)contrasted with functional magnetic resonance imaging(fMRI)during performance of paced visual serial addition test(PVSAT).The group studies were analyzed by using SPM2. White matter was investigated by using diffusion tensor imaging(DTI)and fractional anisotropy(FA)was calculated with the software of DTV-Ⅱ.The activity map was overlaid upon FA maps.The relations between BOLD response and FA values in fronto-parietal lobe were statistically analyzed.Results:The fronto-parietal cortex was mainly region activated by a working memory task,including bilateral inferior parietal lobe and the inferior frontal gyrus,the left superior frontal gyrus,the left medial frontal gyrus and the anterior part of the cingulated gyrus.Overlay of fMRI map upon FA map revealed that activated voxels were almost exclusively in regions of low anisotropy(P0.01).The FA values in fronto-parietal white matter in left(dominant hemisphere)were higher than those in right(P0.02).Conclusion:The combination of both techniques demonstrated that the working memory function was correlated with the maturation of white matter in the fronto-parietal lobes.