Michel C M, Pascual-Marqui R D, Strik W K, Koenig T, Lehmann D
Department of Neurology, University Hospital, Zürich, Switzerland.
J Neural Transm Gen Sect. 1995;99(1-3):157-71. doi: 10.1007/BF01271476.
The topic of this study was to evaluate state-dependent effects of diazepam on the frequency characteristics of 47-channel spontaneous EEG maps. A novel method, the FFT-Dipole-Approximation (Lehmann and Michel, 1990), was used to study effects on the strength and the topography of the maps in the different frequency bands. Map topography was characterized by the 3-dimensional location of the equivalent dipole source and map strength was defined as the spatial standard deviation (the Global Field Power) of the maps of each frequency point. The Global Field Power can be considered as a measure of the amount of energy produced by the system, while the source location gives an estimate of the center of gravity of all sources in the brain that were active at a certain frequency. State-dependency was studied by evaluating the drug effects before and after a continuous performance task of 25 min duration. Clear interactions between drug (diazepam vs. placebo) and time after drug intake (before and after the task) were found, especially in the inferior-superior location of the dipole sources. It supports the hypothesis that diazepam, like other drugs, has different effects on brain functions depending on the momentary functional state of the brain. In addition to the drug effects, clearly different source locations and Global Field Power were found for the different frequency bands, replicating earlier reports (Michel et al., 1992).
本研究的主题是评估地西泮对47通道自发脑电图图谱频率特征的状态依赖性影响。采用了一种新方法，即快速傅里叶变换 - 偶极子近似法（Lehmann和Michel，1990），来研究其对不同频带图谱强度和地形图的影响。图谱地形图由等效偶极子源的三维位置表征，图谱强度定义为每个频率点图谱的空间标准差（全局场功率）。全局场功率可被视为系统产生能量量的一种度量，而源位置给出了在特定频率下活跃的大脑中所有源的重心估计。通过评估持续25分钟的连续执行任务前后的药物效果来研究状态依赖性。发现药物（地西泮与安慰剂）与药物摄入后时间（任务前后）之间存在明显的相互作用，尤其是在偶极子源的上下位置。这支持了这样的假设，即地西泮与其他药物一样，根据大脑的瞬时功能状态对脑功能有不同影响。除了药物效果外，还发现不同频带的源位置和全局场功率明显不同，这重复了早期的报道（Michel等人，1992）。
