语义记忆脑功能区偏侧化的功能磁共振成像研究

A study on functional lateralization of semantic memory in human brain by functional magnetic resonance imaging technique

目的通过功能磁共振成像(fMRI)技术检测健康人脑语义记忆功能区的分布特点。方法14名右利手健康志愿者进行配对词语联想学习记忆任务时行fMRI扫描,该任务可有代表性地反映受试者的语义记忆。实验采用组块设计并选用SPM99软件行数据分析和脑功能区定位,记录各激活脑区的像素值并计算偏侧化指数LI值。结果经单样本t检验,阈值设为P<0.005时,记忆编码时主要激活脑区为左枕叶和左额上中回,提取时主要激活左顶叶、左枕叶和左额中下回;而右半球在两阶段均较少激活。编码和提取激活脑区像素值LI值分别为0.81和0.73。结论语义记忆的脑功能区有显著的左半球优势;记忆编码和提取阶段所激活的脑区有所差别,但均主要分布于左外侧裂语言区的周围。

Objective To investigate the characteristic distribution of semantic memory functional areas in human brain by functional magnetic resonance imaging （fMRI） technique. Methods Fourteen right-handed normal volunteers participated in a test of paired-word associative learning and memory, which was a representative semantic memory task and the fMRI data were recorded simultaneously. Control tasks were performed for the block-design. SPM 99 was used to analyze the data and to obtain the activated brain regions. Numbers of activated voxels were used to calculate lateralization index （LI）. Results When the threshold was set as P 〈 0. 005, using a one-sample t-test, the superior and middle gyms of the left frontal lobe and the left occipital lobe were activated remarkably during the encoding process of the memory task. During the retrieval process, the prominently activated brain regions were the left parietal lobe, The left occipital lobe, the inferior and middle frontal gyms were also obviously activated during this phase. However, the right brain regions were less activated during the both phases. LI of the numbers of activated voxels during the encoding and the retrieval process were 0. 81 and 0. 73, respectively. Conclusions The results of this study reveal that the functional areas of semantic memory in human brain are localized with the functional lateralization in the left hemisphere. The activated areas of the encoding process and the retrieval process are different. But the mainly activated areas during the semantic memory in the cerebral cortex form an arcuate area surrounding the classic perisylvian language zone.