What is an EEG?
Conventional Electroencephalography (EEG) is a technique where the brain’s electrical activity is measured and recorded through sensors on the scalp. The measurement of electrical patterns in the brain are commonly know as brainwaves. These waveforms include a mixture of frequencies, amplitudes, waveforms, locus of phenomena, and regulation of voltage and frequencies which all represent brain activity.
What is a qEEG/ Brain Mapping?
Quantitative EEG (qEEG), also know as Brain Mapping, is a computer analysis of the EEG signal using 19 or more channels of simultaneous EEG recording. Raw EEG data is first recorded, then analyzed and compared against a reference database of “normal” subjects. This type of evaluation is used as an extension of the EEG interpretation, to provide further analyses of brain function for clinical purposes to treat a variety of conditions. The rhythmic cycles observed in the EEG recording represent the brain activity between the cortex and the thalamus.
The 19 channels are represented by 19 electrodes located inside a cap which is placed on the head, against the scalp, to evaluate brainwave function. This placement is called the 10-20 International System of Electrode Placement. The cap, with its 19 channels, produces an analysis of the brainwaves in terms of numbers that represent elements of the brainwave such as frequency, voltage/amplitude or power, location of a phenomena, waveform shape, waveform occurrence, regulation of voltage and frequency, and reactivity. When these elements are combined with other evaluation measures we can, with relative accuracy, determine the type and location of the neurofeedback.
The procedure usually takes between 30 and 45 minutes and consists of placing a cap, similar to a snug swimming cap, which contains small electrodes on the head. These electrodes measure the electrical activity coming from the brain. This procedure is done while the client is sitting in a chair with his eyes open and then closed, or while the client is performing a task like reading. The client is given directions to remain calm and in a resting state throughout the assessment process.
The results of the qEEG analysis are displayed in the form of statistical tables and topographic maps. These topographic maps provide a convenient schematic representation of the relationships among the EEG waveforms, map displays, and the results of the statistical analyses. The data collected from the qEEG are statistically compared to a large normative database which provides information about how the brain waves should look and operate at different ages. Once compared to this database the clinician can determine if the client’s brainwave patterns are different from normal, and if so, how are they different and where do these differences occur.
The qEEG can aid in the diagnoses of many conditions and diagnoses because it can help describe specific areas of strength and weaknesses in brain function.
The qEEG can help reveal the underlying neurophysiology associated with a variety of disorders such as ADD/ADHD, TBI, learning disabilities, language disorders, sensory processing disorders, auditory processing disorders, anxiety, depression, post-traumatic stress disorder, obsessive compulsive disorder, insomnia, emotional regulation difficulties reading disorders, trauma, and other cognitive disorders.
Different qEEG Categories
There are three categories of qEEG spectral variables that are of clinical value for treatment purposes. These variables are all presented in the qEEG/Brain map analysis as part of the overall assessment of brain function. These variable are:
- 1. Power/amplitude
- 2. Coherence and/or phase
- 3. Derived ratios of amplitude and/or coherence and/or phase
Neurofeedback training will involve at least one and often a combination of approaches to address these variables.