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Study on Neuromagnetic Imaging and Modeling of MEG Activities

MEG 活动的神经磁成像和建模研究

基本信息

批准号：
63850090
负责人：
UENO Shoogo
金额：
$ 20.99万
依托单位：
Department of Electronics, Faculty of Engineering, Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B).
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

During the past decade, substantial advances in the understanding of the functional organization of the human brain have been made through the technique of MEG topographic mapping. Most of these investigations were concerned with the estimation and localization of sources which were modeled as single current dipoles positioned in a semi infinite volume conductor with homogeneous conductivities. However, the sources in the brain are complex, and the head as a volume conductor consisits of different materials with different electrical conductivities. The influence of these inhomogeneities on the MEG topography is studied by a computer simulation, modeling the sources as single or multiple dipoles located in inhomogeneous volume conductors. The computer simulation suggests some important aspects in estimation of source localization. (1) Flux reversal phenomena can be observed in MEG to pographic patterns in special cases where conductivities of the inhomogeneous regions change with pathol … More ogical conditions. The flux reversal can be caused by the change of flow patterns of currents which flow on the surface of boundary between different inhomogeneous regions in the head. (2) Radially oriented dipoles produced magnetic fields outside the sphere due to the effects of inhomogeneities. Normal components of magnetic fields perpendicular to the surface of the sphere generated by the effects of inhomogeneities were determined by volume current. The sources of MEG activities in human subject during sleep were also studied, The following results were obtained ; (3) Sources of K-complexes can be modeled by two current dipoles positioned in the deeper parts of the head. (4) Delta activities in sleep stages 3 and 4 have many sources with different frequencies. Some of these sources can be detected by MEG measurements, but are difficult to detect with EEG measurements. The MEG technique has a potential advantage to provide important information concerning brain function which cannot be obtained using the EEG measurements. Less

在过去的十年中，通过脑磁图地形图技术，对人类大脑功能组织的理解取得了实质性进展。这些研究大多涉及源的估计和定位，这些源被建模为位于具有均匀电导率的半无限体积导体中的单个电流偶极子。然而，大脑中的源是复杂的，并且头部作为体积导体由具有不同电导率的不同材料组成。这些不均匀性对脑磁图地形的影响进行了研究，通过计算机模拟，建模的源位于不均匀的体积导体的单个或多个偶极子。计算机模拟表明，一些重要方面的估计源定位。(1)在脑磁图中，当不均匀区域的电导率随病理变化时，可观察到磁流反转现象 ...更多信息逻辑条件。磁通反转是由于流过磁头内不同非均匀区域边界表面的电流流型发生变化而引起的。(2)径向取向的偶极子产生的磁场以外的领域由于不均匀性的影响。由不均匀性的影响所产生的垂直于球体表面的磁场的法向分量由体积电流确定。本文还研究了人睡眠时脑磁图的来源，得到以下结果：（3）K复合波的来源可以用位于头部深部的两个电流偶极子来模拟。(4)睡眠阶段3和4中的δ活动有许多不同频率的来源。这些源中的一些可以通过MEG测量来检测，但是难以通过EEG测量来检测。MEG技术具有潜在的优势，可以提供使用EEG测量无法获得的关于脑功能的重要信息。少