Measurement and analysis of language functions in the frontal regions using magnetoencephalography and functional magnetic resonance imaging

在本研究中，我们使用磁成像技术测量和分析了额区的语言功能。本研究由四个部分组成：(1)脑磁图测量与分析技术的改进；(2)时频分析方法的建立；(3)诱发额区fMRI激活的语言任务的构建；(4)脑磁图对额区语言功能的测量与分析。本报告主要介绍第(4)节的结果，因为第(1)-(3)节是第(4)节的基础研究。在脑磁图测量中，受试者被指示执行一项词分类任务，该任务在fMRI研究中诱发皮层活动。用偶极子源分析、频率分析和时频分析对脑磁图的响应进行分析。在偶极子源分析中，几乎所有偶极子都分布在时间区域，只有少数偶极子分布在额区。然而，在频率和调频分析中，在颞区和额区观察到了磁响应。α带幅度在颞区显着，而增量带幅度在额区明显。这一结果表明，语言任务激活了颞叶和额叶区域的神经元。观察到其中一名受试者的脑磁图阿尔法频段的去同步化。结果表明，语言任务所诱发的神经活动存在于额叶区域，这些活动与脑磁图的增量带有关。因此，语言任务中的神经活动可能很难与额叶区域的任务集同步。

In this research, we measured and analyzed the language function in the frontal regions using magnetic imaging techniques. This research was composed of four sections : (1)improvement in measurement and analysis techniques of MEG, (2)establishment of the time-frequency analysis method, (3)construction of language tasks that induce fMRI activation in the frontal regions, (4)measurement and analysis of the language function in the frontal regions using MEG. This report mainly presents the results of section (4)since sections (1)-(3) are fundamental researches for section (4).In an MEG measurement, subjects were instructed to perform a word categorization task that evoked cortical activities in an fMRI study. The MEG responses were analyzed using dipole source analysis, frequency analysis, and time-frequency analysis. In the dipole source analysis, almost all the dipoles were localized in the temporal regions, while only a few dipoles were localized in, the frontal regions. However, in the frequency and tune-frequency analysis, magnetic responses were observed in the temporal and frontal regions. The alpha band amplitude was remarkable in the temporal regions while the delta band amplitude was distinctive in the frontal regions. This result showed that neurons in the temporal and frontal regions were activated by the language task. Desynchronization of the alpha band MEG in the temporal regions was observed for one of the subjects. This does not indicate the correlation of neural activities with a magnitude of the alpha band.The results suggested that neural activities evoked by language tasks were found in the frontal regions, and these activities were related to the delta band MEG. Therefore, neural activities during language tasks may hardly synchronize with task onsets in the frontal regions.