Ioannides Andreas A
Laboratory for Human Brain Dynamics, RIKEN Brain Science Institute, Saitama, Japan.
Neuroscientist. 2006 Dec;12(6):524-44. doi: 10.1177/1073858406293696.
Magnetoencephalography (MEG) is a noninvasive neuroimaging method for detecting, analyzing, and interpreting the magnetic field generated by the electrical activity in the brain. Modern hardware can capture the MEG signal at hundreds of points around the head in a snapshot lasting only a fraction of a millisecond. The sensitivity of modern hardware is high enough to permit the extraction of a clean signal generated by the brain well above the noise level of the MEG hardware. It is possible to identify signatures of superficial and often deep generators in the raw MEG signal, even in snapshots of data. In a more quantitative way, tomographic images of the electrical current density in the brain can be extracted from each snapshot of MEG signal, providing a direct correlate of coherent collective neuronal activity. A number of recent studies have scrutinized brain function in the new spatiotemporal window that real-time tomographic analysis of MEG signals has opened. The results have allowed the variability in a single area to be seen in the context of activity in other areas and background rhythmic activity. In this view, normal brain function is seen as a cascade of extremely fast events and the unfolding of specialized processes, segregated in space and time and organized into well-defined stages of processing.
脑磁图（MEG）是一种用于检测、分析和解释大脑电活动所产生磁场的非侵入性神经成像方法。现代硬件能够在仅持续几分之一毫秒的瞬间，捕捉头部周围数百个点的脑磁图信号。现代硬件的灵敏度足够高，能够提取出大脑产生的纯净信号，该信号远高于脑磁图硬件的噪声水平。即使在数据快照中，也有可能在原始脑磁图信号中识别出浅表和通常较深层信号源的特征。以一种更定量的方式，可以从脑磁图信号的每个快照中提取大脑电流密度的断层图像，这直接关联了连贯的集体神经元活动。最近的一些研究在脑磁图信号实时断层分析所开启的新时空窗口中仔细研究了脑功能。这些结果使得能够在其他区域的活动和背景节律活动的背景下，观察单个区域的变异性。从这个角度来看，正常脑功能被视为一系列极其快速的事件以及专门过程的展开，这些过程在空间和时间上是分离的，并组织成明确的处理阶段。
