Singh Krish D, Barnes Gareth R, Hillebrand Arjan, Forde Emer M E, Williams Adrian L
The Wellcome Trust Laboratory for MEG Studies, Neurosciences Research Institute, Aston University, Birmingham, United Kingdom.
Neuroimage. 2002 May;16(1):103-14. doi: 10.1006/nimg.2001.1050.
Using group functional Magnetic Resonance Imaging (fMRI) and group Magnetoencephalography (MEG) we studied two cognitive paradigms: A language task involving covert letter fluency and a visual task involving biological motion direction discrimination. The MEG data were analyzed using an adaptive beam-former technique known as Synthetic Aperture Magnetometry (SAM), which provides continuous 3-D images of cortical power changes. These images were spatially normalized and averaged across subjects to provide a group SAM image in the same template space as the group fMRI data. The results show that frequency-specific, task-related changes in cortical synchronization, detected using MEG, match those areas of the brain showing an evoked cortical hemodynamic response with fMRI. The majority of these changes were event-related desynchronizations (ERDs) in the 5-10 Hz and 15-25 Hz frequency ranges. Our study demonstrates how SAM, spatial normalization, and intersubject averaging enable group MEG studies to be performed. SAM analysis also allows the MEG experiment to have exactly the same task design as the corresponding fMRI experiment. This new analysis framework represents an important advance in the use of MEG as a cognitive neuroimaging technique and also allows mutual cross-validation with fMRI.
我们使用群组功能磁共振成像（fMRI）和群组脑磁图（MEG）研究了两种认知范式：一种是涉及隐蔽字母流畅性的语言任务，另一种是涉及生物运动方向辨别的视觉任务。MEG数据使用一种称为合成孔径磁测量法（SAM）的自适应波束形成技术进行分析，该技术可提供皮质功率变化的连续三维图像。这些图像在空间上进行归一化处理，并在受试者之间进行平均，以在与群组fMRI数据相同的模板空间中提供群组SAM图像。结果表明，使用MEG检测到的特定频率、与任务相关的皮质同步变化与fMRI显示诱发皮质血流动力学反应的脑区相匹配。这些变化中的大多数是5-10Hz和15-25Hz频率范围内的事件相关去同步化（ERD）。我们的研究展示了SAM、空间归一化和受试者间平均如何使群组MEG研究得以进行。SAM分析还允许MEG实验与相应的fMRI实验具有完全相同的任务设计。这种新的分析框架代表了将MEG用作认知神经成像技术的一项重要进展，并且还允许与fMRI进行相互交叉验证。
