A quantitative EEG is a brain map. This is an electrical measurement, analysis, and quantification of the brainwaves. The brainwaves are the basis of all brain function and forms a complex self adapting system that holds the patterns of all our abilities and our symptoms. We first gather the raw EEG data, and then we process it through a normative database, which is a database of healthy individuals’ brainwaves of the same age as the client. This gives us a comparison of the client’s brain relative to others’. This is the first step in our assessment process.
The brain mapping process entails placing a cap with 20 measuring sites (electrodes) onto the head of the participant and injecting saline gel into the electrodes. Then, we use the electrodes to pick up microvolts of electrical potentials generated by the brain, which show up as brainwaves (looks like squiggles).
We then interpret the squiggles in their raw form, as well as run them through many types of digitized filters (i.e. different software), that breaks them into their respective components and brainwave bandwidths of Delta (0-4 Hz), theta (5-8 Hz), alpha (9-12 Hz), low beta (13-16 Hz), mid beta (17-25Hz), hi beta (26-40Hz), and gamma (41-70Hz).
With this data and the use of different databases of hundreds of others’ EEGs, we are able to determine where the individual is different from the norm—for better or for worse. We are able to look not only at the brainwaves, but also the relationship of the brainwaves to one another, the symmetry of the brain, the stability of the brainwave relationships, and the areas where the brain might be generating problematic signals, manifesting in problematic symptoms and behaviors.
It is important to realise that the usefulness of the QEEG is in planning how to address the symptoms and functional deficits and not to diagnose. Diagnosis is a label on a set of symptoms and increasingly brain science is indicating that there are many different patterns (phenotypes) that might manifest as the same set of symptoms. Ultimately it is what is happening at the brain level that shows the clearest path to improving mental health. These phenotypes can predict medication effectiveness and point to the best ways to help the brain learn to shift out of dysfunctional patterns that generate symptom clusters.