Pratt H, Geva A B, Feingold K, Zeevi Y Y
Evoked Potentials Laboratory, Haifa, Israel.
Acta Otolaryngol. 1995 May;115(3):363-6. doi: 10.3109/00016489509139330.
The generators of auditory brainstem evoked potentials (ABEPs) are generally agreed to be located between the auditory nerve and upper pons. Thus, they are all located within a few cm from the center of the head. Three-channel Lissajous' trajectory (3CLT) provides the amplitude and orientation of a centrally located equivalent dipole of surface recorded activity. Volume conductor theory predicts decreased spatial resolution of source estimation the deeper the source. In this study we compared source estimates obtained with 3CLT, using three orthogonal differential channels, with those obtained with two other source estimation methods: i) setting the generators at their known anatomical coordinates and calculating orientation and magnitude of the source (dipole localization method--DLM); ii) estimation of all source parameters, including the number of sources by wavelet-type decomposition, without assumptions on the location of the sources (multiple source estimate--MSE). 3CLT, DLM and MSE all converged on magnitudes and orientations that were not significantly different from each other, and locations that were within a few cm of each other. In conclusion, although 3CLT can only estimate a single, centrally located equivalent dipole, in the specific case of ABEPs, it provides the same information available from the more demanding source estimate methods. In addition to the considerable saving in recording channels, 3CLT is reference-independent and thus avoids ambiguities resulting from the choice of reference.
听觉脑干诱发电位（ABEP）的发生器通常被认为位于听神经和脑桥上段之间。因此，它们都位于距离头部中心几厘米的范围内。三通道李萨如图形轨迹（3CLT）可提供表面记录活动的位于中心的等效偶极子的幅度和方向。容积导体理论预测，源越深，源估计的空间分辨率越低。在本研究中，我们将使用三个正交差分通道的3CLT获得的源估计与通过其他两种源估计方法获得的源估计进行了比较：i）将发生器设置在其已知的解剖坐标处，并计算源的方向和大小（偶极子定位方法——DLM）；ii）估计所有源参数，包括通过小波型分解估计源的数量，而不对源的位置做任何假设（多源估计——MSE）。3CLT、DLM和MSE在幅度和方向上都相互收敛，差异不显著，在位置上也彼此相距几厘米。总之，尽管3CLT只能估计单个位于中心的等效偶极子，但在ABEP的特定情况下，它提供了与要求更高的源估计方法相同的信息。除了在记录通道方面有显著节省外，3CLT与参考无关，因此避免了因参考选择而产生的模糊性。
