Scherg M
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York.
Brain Topogr. 1992 Winter;5(2):103-11. doi: 10.1007/BF01129037.
Functional imaging of electric brain activity requires specific models to transform the signals recorded at the surface of the human head into an image. Two categories of model are available: single-time-point and spatio-temporal methods. The instantaneous methods rely only on the few voltage differences measured at one sampling point. To create a spatial image from this limited information, they require strict assumptions that rarely conform with the underlying physiology. Spatio-temporal models create two kinds of images: first, a spatial image of discrete equivalent multiple dipoles or regional sources, and second, an image of source current waveforms that reflect the temporal dynamics of the brain activity in circumscribed areas. The accuracy of the spatial image is model dependent and limited, but it can be validated from the spatio-temporal data by the "regional source imaging" technique, introduced here. The source waveforms are linear combinations of the scalp waveforms, and thus, specific derivations which image local brain activities at a macroscopic level. Brain source imaging of somatosensory evoked potentials revealed temporally overlapping activities from the brainstem, thalamus and from multiple sources in the region of the contralateral somatosensory projection areas.
脑电活动的功能成像需要特定模型，以便将在人头部表面记录的信号转换为图像。有两类模型可供使用：单时间点模型和时空模型。瞬时模型仅依赖于在一个采样点测量的少数电压差。为了从这些有限的信息中创建空间图像，它们需要严格的假设，而这些假设很少与潜在的生理学相符。时空模型创建两种图像：第一，离散等效多个偶极子或区域源的空间图像；第二，源电流波形图像，该图像反映了限定区域内脑活动的时间动态。空间图像的准确性取决于模型且有限，但可以通过此处介绍的“区域源成像”技术从时空数据中进行验证。源波形是头皮波形的线性组合，因此是在宏观水平上对局部脑活动进行成像的特定推导。体感诱发电位的脑源成像揭示了来自脑干、丘脑以及对侧体感投射区域内多个源的时间上重叠的活动。
