fMRI及DTI技术在成人工作记忆研究的初步探索

Combined Study of fMRI and DTI for Working Memory of Adults

目的:联合应用脑功能磁共振成像(BOLD-fMRI)和弥散张量成像(DTI)两种磁共振技术,探索工作记忆功能激活部位与叶间白质纤维束的关系。方法:健康志愿者16名,以步进式视觉累加试验作为刺激模式,扫描获得fMRI激活图及各向异性(FA)图。将两者叠加,选取双侧额顶叶白质兴趣区测量其部分FA值。结果:①额顶叶皮质为工作记忆功能最主要的激活区;②脑的激活像素几乎均位于FA程度低的区域(P<0.01);③左额顶间白质FA值较对侧高(P<0.02)。结论:联合应用fMRI和DTI技术提示成人工作记忆功能与额顶叶白质纤维髓鞘化程度密切相关。

Aim： To explore whether there is relation anisotropy of the fronto-parietal white matter in adults by between brain activity of working memory and 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 （P〈0.01）. The FA values in fronto-parietal white matter in left （dominant hemisphere） were higher than those in right （P〈0.02）. 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.