通过脑电偶极子进行视觉诱发响应的动态提取

DYNAMIC EXTRACTION OF VISUAL EVOKED POTENTIAL BY MEANS OF DIPOLE LOCALIZATION

透发电位的动态提取在临床医学及神经科学研究中有重要意义。本文以按国际１０／２０电极系统测得的１６导脑电记录为原始数据、通过空间分析（包括奇异值分解、主分量分析、空间滤波、相关去噪声等），在定位出的脑电偶极子的协助下，充分利用观察数据中的时空信息，以达到动态提取的目的。提出一种“空间因子求逆法”来最优地估计偶极子参数，并降低噪声对求逆的影响。目前已达到由连续两次刺激记录便可提取视觉诱发响应。这一方法的主要局限是要求信号在被处理的时间范围内保持空间模式基本不变。计算机仿真和临床数据分析证明了方法的可行性。

Dynamic extraction of evoked potential is of great importance both inclinical medicine and in neuroscience investigation.Sixteen channels EEGrecord measured with international 10/20 electrodes system were used as theoriginal data.Spatial analysis(including singular value decomposition,principal component analysis,spatial filtering and correlation technique for noise elimination) is integrated with dipole localization so as to fully util ize the spatial temporal information implied in the observed data.Various techniques were employed to effectively reduce noise.A Spatial Factor Inversion Method was proposed to estimate the dipole parameters optima lly and to lower the sensitivity of the procedure of inversion to noise.As a result,visual evoked potential(VEP) could be effectively extracted using only two consecutive stimulation records and the dynamic evolution of VEP might be manifested.The main limitation of the proposed method is that the spatial patterns of the signal should remain nearly time invariant during the analyzing time interval.Initial results obtained by computer simulation and by clinical data review were rather encouraging.