Tesche C D, Uusitalo M A, Ilmoniemi R J, Huotilainen M, Kajola M, Salonen O
Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
Electroencephalogr Clin Neurophysiol. 1995 Sep;95(3):189-200. doi: 10.1016/0013-4694(95)00064-6.
We describe the use of signal-space projection (SSP) for the detection and characterization of simultaneous and/or sequential activation of neuronal source distributions. In this analysis, a common signal space is used to represent both the signals measured by an array of detectors and the underlying brain sources. This presents distinct advantages for the analysis of EEG and MEG data. Both highly localized and distributed sources are characterized by the components of the field patterns which are measured by the detectors. As a result, a unified description of arbitrary source configurations is obtained which permits the consistent implementation of a variety of analysis techniques. The method is illustrated by the application of SSP to auditory, visual and somatosensory evoked-response MEG data. Single-trace evoked responses obtained by SSP of spontaneous activity demonstrate that a considerable discrimination against both system noise and uncorrelated brain activity may be achieved. Application of signal-space projections determined in the frequency domain to spontaneous activity illustrates the possibility of including temporal relationships into the analysis. Finally, we demonstrate that SSP is particularly useful for the description of multiple sources of distributed activity and for the comparison of the strengths of specific neuronal sources under a variety of different paradigms or subject conditions.
我们描述了使用信号空间投影（SSP）来检测和表征神经元源分布的同时和/或顺序激活。在该分析中，一个公共信号空间用于表示由探测器阵列测量的信号以及潜在的脑源。这为脑电图（EEG）和脑磁图（MEG）数据的分析带来了明显优势。高度局部化和分布式的源都由探测器测量的场模式分量来表征。结果，获得了对任意源配置的统一描述，这允许各种分析技术的一致实施。通过将SSP应用于听觉、视觉和体感诱发反应MEG数据来说明该方法。通过对自发活动进行SSP获得的单迹诱发反应表明，可以对系统噪声和不相关的脑活动实现相当程度的区分。将在频域中确定的信号空间投影应用于自发活动说明了将时间关系纳入分析的可能性。最后，我们证明SSP对于描述分布式活动的多个源以及在各种不同范式或受试者条件下比较特定神经元源的强度特别有用。
