Stamoulis Catherine, Chang Bernard S
Harvard Medical School, Children's Hospital Boston, Departments of Neurology and Radiology, Clinical Research Program, 300 Longwood Ave., Boston MA 02115, USA.
Int Conf Digit Signal Process Proc. 2011 Jul 6;2011. doi: 10.1109/ICDSP.2011.6004976.
This paper presents a novel approach for the estimation of frequency-specific EEG scale modulations by the directional anisotropy of the brain, using the Mellin transform [1, 2, 3]. In the case of epileptic sources, the activity recorded by routine scalp EEG includes contributions not only from a seizure's primary propagation path but also from secondary paths and unrelated to the seizure activity. In addition, the anisotropy of the brain directionally modulates the seizure-related signal component. We estimated patient-specific direction-specific, frequency-locked scale shifts. During the ictal interval, these shifts occurred at frequencies ≥50 Hz. We further estimated the effect of scale modulations on time-delay estimation. Larger time-delays were estimated from EEGs that had been corrected by a scale factor prior to this estimation. Thus, corrections for non-linear scaling of EEGs may ultimately improve time-delay estimation for source localization, particularly in cases of seizures rapidly propagating to large areas of the brain.
本文提出了一种新颖的方法，利用梅林变换[1,2,3]，通过大脑的方向各向异性来估计特定频率的脑电图（EEG）尺度调制。在癫痫源的情况下，常规头皮脑电图记录的活动不仅包括来自癫痫发作主要传播路径的贡献，还包括来自次要路径且与癫痫发作活动无关的贡献。此外，大脑的各向异性会对癫痫相关信号成分进行方向调制。我们估计了患者特定的方向特定、频率锁定的尺度偏移。在发作间期，这些偏移发生在频率≥50Hz时。我们还进一步估计了尺度调制对时延估计的影响。在进行时延估计之前，对经尺度因子校正的脑电图估计出的时延更大。因此，对脑电图的非线性缩放进行校正最终可能会改善源定位的时延估计，特别是在癫痫发作迅速传播到大脑大面积区域的情况下。
