The Quantitative Electroencephalogram and the Use of Normative Databases
This report describes the scientific, technical, and clinical bases for the use of quantitative EEG (QEEG) in the assessment of clients and in treatment monitoring. Specific attention is directed toward the use of normative databases and z-scores as a form of standardized referencing for reporting and training purposes. Normative databases have general value and are of particular value when connectivity metrics are being used. It is shown that the use of z = 0 as an average over time corresponds to a state of optimum flexibility, adaptability, and readiness. The use of the inverse solution (LORETA) methods is also described, as well as use of those methods within the QEEG and normative model. Advantages as well as shortcomings of this approach are described and discussed.
Earliest published EEG by Hans Berger in 1932. Top trace recorded with Edelmann string galvanometer. Middle trace recorded with Siemens double-coil oscillograph. Bottom trace: 10 Hz reference. The waves reveal all of the recognized components, including alpha, beta, theta, and delta (Gloor, 1969, p. 156).
Early implementation of a photographic-based (“mechanical-electrical integrator”) Fourier analyzer (Grass & Gibbs, 1938).
Wooden model of a compressed spectral array as an early attempt to image three-dimensional spectral information before the availability of computers (Gibbs & Knott, 1949).
Example of a spinal X ray expressed in z scores. The intensity of the image is converted into z scores, so that abnormal areas are readily evident.
Thomas Ros explains self-organized self-criticality and scale-free dynamics of systems (Ros et al., 2017).
Three-dimensional (voxel) image of mesial temporal gamma activity in an advanced meditator. Image produced by BrainAvatar (Collura, 2012b) using sLORETA transform on 19 scalp electrodes, and comparing voxel data with the BrainDX sLORETA z-score database (Cantor, 2018).
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