图片命名任务脑激活的时空特征

The spatiotemporal characteristics of brain activation during picture naming tasks

目的:探讨区组循环范式下图片命名任务中全脑在时间、空间维度内的变化,以及不同语义相关程度对脑区激活的影响。方法:选取健康成年右利手志愿者10例。采用区组循环范式,包括相同类别图片命名任务和不同类别图片命名任务。应用脑磁图(magnetoencephalography,MEG)检测图片命名任务中全脑在不同时间窗内的激活强度。结果:在视觉相关时间窗内,相同类别图片命名任务的左侧额极(1.421±0.468)、右侧额极(1.431±0.435)、左侧眶额回(1.601±0.620)、右侧眶额回(1.567±0.556)、左侧额上回(1.899±0.062)、右侧顶上回(5.218±0.678)和左侧舌回(5.016±0.088)激活高于不同类别图片命名任务(1.038±0.217,1.131±0.235,1.312±0.316,1.253±0.340,1.710±0.151,4.538±0.478,4.275±0.251),差异有统计学意义(P<0.05);在语义相关时间窗内,不同类别图片命名任务的左侧中央旁小叶(3.176±0.392)、右侧楔叶(4.190±0.330)、左侧扣带回后部(2.430±0.196)和右侧扣带回后部(2.405±0.236)激活高于相同类别图片命名任务(2.594±0.254,3.626±0.560,2.038±0.115,1.990±0.094),差异有统计学意义(P<0.05);在语音相关时间窗内,不同类别图片命名任务的左侧颞上沟(3.709±0.274)、左侧颞上回(3.901±0.380)、左侧颞中回(3.340±0.380)、左侧颞横回(4.449±0.265)、左侧缘上回(3.205±0.308)、左侧岛叶(3.140±0.204)、左侧扣带回前部(2.217±0.194)和右侧扣带回前部(2.341±0.167)激活高于相同类别图片命名任务(2.662±0.300,2.503±0.342,2.614±0.324,2.633±0.281,2.663±0.278,2.248±0.284,1.818±0.315,2.005±0.437),差异有统计学意义(P<0.05)。结论:不同时间窗、语义相关程度导致脑区激活差异。在视觉相关时间窗内,相同类别图片命名任务时前额叶优势激活,可能与持续注意和类别判断有关;在语义加工和语音编码时间窗内,不同类别图片命名任务时左侧颞叶、左侧岛叶及双侧边缘系统为主的优势激活,与语义处理和语音自省有关。

Objective:To explore the temporal and spatial changes of the whole brain during the picture naming tasks and the influence of different semantic similarity in the blocked-cyclic paradigm.Methods:Ten healthy right-handed adults were selected.The blocked-cyclic paradigm is divided into two naming tasks consist of related and unrelated pictures.The brain activation of the whole brain in different time windows was recorded by magnetoencephalography(MEG)during the picture naming tasks.Results:In the visual-related time windows,the dominant regions appeared in the related picture naming task,located in left frontal pole(1.421±0.468),right frontal pole(1.431±0.435),left orbitofrontal gyrus(1.601±0.620),right orbitofrontal gyrus(1.567±0.556),left superior frontal gyrus(1.899±0.062),right superior parietal gyrus(5.218±0.678)and left lingual gyrus(5.016±0.088)compared with the unrelated picture naming task(1.038±0.217,1.131±0.235,1.312±0.316,1.253±0.340,1.710±0.151,4.538±0.478,4.275±0.251),the differences were statistically significant(P<0.05).In the semantic-related time windows,the dominant regions appeared in the unrelated picture naming task,located in left paracentral lobule(3.176±0.392),right cuneus(4.190±0.330),left posterior cingulate(2.430±0.196)and right posterior cingulate(2.405±0.236)compared with the related picture naming task(2.594±0.254,3.626±0.560,2.038±0.115,1.990±0.094),and the differences were statistically significant(P<0.05).In the phonological-related time windows,the dominant regions appeared in the unrelated picture naming task,located in left superior temporal sulcus(3.709±0.274),left superior temporal gyrus(3.901±0.380),left middle temporal gyrus(3.340±0.380),left transverse temporal gyrus(4.449±0.265),left supramarginal gyrus(3.205±0.308),left insula(3.140±0.204),left anterior cingulate(2.217±0.194)and right anterior cingulate(2.341±0.167)compared with the related picture naming task(2.662±0.300,2.503±0.342,2.614±0.324,2.633±0.281,2.663±0.278,2.248±0.284,1.818±0.315,2.005±0.437),and the differences were statistically significant(P<0.05).Conclusion:In different time windows,semantic similarities can lead to differences in brain activation.The related picture naming task can cause the dominant activation of bilateral prefrontal lobe in the visual processing stage,which may be related to sustained attention and category judgment while the unrelated picture naming task can cause dominant activation of the left temporal gyrus,left insula and bilateral limbic system during speech processing,which corresponds to semantic coding and phonology introspection.