What is QEEG Brain Mapping?
Electrical activity generated by the body’s muscles as they contract are recorded as an electromyogram from sensors attached to the skin over the muscles and shown graphically in an electromyograph (EMG). The electrical activity created by contractions of the heart is recorded as an electrocardiogram and shown as an electrocardiograph (ECG). In a similar fashion, the raw unfiltered electrical activity generated by the brain is measured and recorded as an electroencephalogram and shown in an electroencephalograph (EEG).
Electroencephalographs showing the raw unfiltered EEG signal are called clinical EEGs and are often used in hospital settings by neurologists to evaluate epilepsy or determine if there is serious brain pathology, such as a tumor. In these applications, the raw EEG tracings from multiple recording sites are visually examined by the neurologist for abnormal waveforms or spikes appearing in the tracings from one or more electrodes that might be indicative of an underlying brain disorder. The EEG is used only for testing in most hospital settings and the neurologist is primarily interested in wave morphology (i.e., shape). Certain abnormalities in wave morphology may be indicative of an underlying problem such as a seizure focus in epilepsy or a brain tumor, for example.
Another way of looking at the EEG data recorded from multiple locations over the scalp is to have the computer analyze the frequency and amplitude characteristics of the brain waves as well as other complex data that may be derived from the raw EEG and produce something called a quantitative electroencephalograph (QEEG) brain map— technically, a topographical representation of the distribution over the cortex of the EEG waveforms generated by the brain. A good example of topographic mapping is provided by the colorful daily weather maps shown on television. Average temperature gradation is depicted topographically on a national map based on a mathematical computation. It is similar when converting the raw EEG activity into a QEEG brain map.
The illustration below, shows the raw EEG data as recorded from 19 scalp locations over the brain cortex and an example of how these data might look after the computer analyses the EEG and converts the raw data into a topographical QEEG brain map showing the different relative amplitudes of selected EEG frequency bands in different colours from black for the lowest amplitude to whte for the highest.
It is important to make a clear differentiation between QEEG tests of the brain and other commonly used, and perhaps more familiar, imaging techniques in medicine. For example, x-rays, Computerized Axial Tomography (CAT) scans and Magnetic Resonance Imaging (MRI), are all used to examine brain anatomy, or structure— they are “structural imaging” techniques that allow us to “see” the physical structure of the brain. The QEEG, on the other hand, measures brain physiology, or function. QEEG is a “functional imaging” technique that looks directly at brain activity or metabolism in “real time”. Other functional imaging techniques that are used in research and sometimes in hospitals are Positron Emission Tomography (PET) scans, Single Photon Emission Tomography (SPECT) scans, and Functional Magnetic Resonance Imaging (fMRI) techniques. These are all much more expensive and complex imaging techniques that look at blood flow or glucose uptake in the brain to give us a time-averaged look at brain metabolism.
A SPECT camera and a colourized SPECT image of the left side of the brain.
The QEEG does not assess the structure of the brain, but rather, evaluates the manner in which a particular person’s brain functions. It is not designed to diagnose tumors, epilepsy, or other structural medical conditions, but rather, gives us the ability to view the dynamic changes taking place throughout the brain during processing tasks and assist in determining which areas of the brain are fully engaged and processing efficiently.
How is the QEEG Brain Map Produced and Used?
Quantitative Electroencephalography (QEEG) is a brain imaging technique that allows us to understand an individual's electrical brain activity and brain function. Creating a map of the brain’s electrical activity is actually fairly straightforward and takes only a couple of hours. It is also completely non-invasive and pain-free.
To perform a QEEG mapping procedure, electrodes, also known as sensors, are typically positioned on the client’s scalp at 19 standardized locations designated by the International 10-20 System (see below). This is usually accomplished by placing a special Lycra cap, much like a bathing cap, is placed on the client’s head. This cap has all the electrodes already attached in their proper position and is then connected to a computer with a special cable.
These recordings are then relayed to computers, which interpret the information and produce a color-coded map of your brain function. During the EEG data recording procedure, the client usually sits in a comfortable chair and is asked to simply sit still with eyes closed for a few minutes. The “eyes closed” recording is usually followed by a second recording with the eyes open and the client simply looking a single spot on the wall in front of him/her to minimize eye-movement. Sometimes recordings are also made while the client is doing some type of reading or mathematical calculation or visual puzzle task.
During the data acquisition phase of the EEG brain mapping, each of the sensors attached to the scalp collects the very faint electrical signals produced by neuronal activity within the brain, primarily from the outer layer or cerebral cortex. The collected EEG data is then processed digitally and stored for later artifacting (i.e., removal of data segments contaminated by eye or muscle movement) and analysis. Once data collection is complete and the data are analyzed, the results can be shown graphically— most often in the form of colour-coded topographical brain maps such as the one shown below.
Through this visual representation, areas of the brain showing more or less activity within a certain frequency band can be easily identified.
Most EEG brain maps show the distribution of EEG activity in amplitude (i.e., microvolts/hertz) or power (i.e., microvolts squared/hertz) units over the cortex in terms of a set of pre-defined frequency bands— namely, Delta (1-4 Hz), Theta (4-8 Hz), Alpha (8-12 Hz), SMR or Beta1 (12-16 Hz), Beta2 (16-20 Hz), Beta3 (20-24Hz), High Beta (24-32 Hz), and Gamma (38-42 Hz). Sometimes maps are produced for each single frequency from 1 to 40 Hz, called “single-bin” maps. Each map is colour-coded to show the amount of activity from lowest to highest. Maps are also sometimes produced to show other variables related to brain functioning such as left versus right power asymmetry, phase and coherence.
What is Neurometric Analysis?
EEG neurometric analysis is the process of statistically comparing an individual’s QEEG data to “normative” data for his/her age and gender peers. A number of researchers and institutions have collected QEEG data from sample populations of “normal” individuals as well as from sample populations of persons identified as having certain psychoneurological problems such as ADHD, learning disabilities, traumatic brain injury, dementia, depression, bipolar disorder, anxiety disorders, obsessive-compulsive disorder, schizophrenia, and alcohol and substance abuse. Many of these QEEG databases are commercially available and can be accessed by EEG neurotherapy practitioners to compare their client’s to one or more selected sample populations and, thereby, determine to what extent the individual client may differ from norms for his/her gender and age as well as to whether the client’s QEEG pattern is statistically similar to that of some identified diagnostic group.
Comparison of the individual client’s QEEG to normative data can be useful in the diagnostic process as well as in the planning of appropriate treatment. Specific QEEG signatures or patterns have been found and validated for a number of different disorders and some databases will permit a statistical pattern analysis of the individual client QEEG data against a selected sample population and generate a statistical estimate of the extent to which the client fits the sample population. For example, a depressed client who has a history of mild head injury may be separately compared to samples of depressed individuals as well as head-injured individuals of the same gender and age to see to what extent the client’s QEEG pattern matches the QEEG signature for depression or head injury. Such an analysis may show that the depression is independent of the head injury or it might show that there clearly is a head injury that may explain the symptoms of depression. Treatment might vary dependent on the outcome of such comparisons.
For example, the QEEG brain maps (below) were produced with the NxLink database program (John, Prischep, Easton) and show the eyes-closed QEEG data of a 7 year-old female diagnosed with ADHD as compared to normative QEEG data for her age and gender. The topographs are colour-coded to show deviation from the norm in Z-score units; with very light blue indicating very much less than normal values (-99.9%tile), black indicating normal values (50%tile), and white indicating very much greater than normal values (+99,9%tile).
Examination of these topographs show that this child has higher than normal (about +2.5 Z-score units) relative amplitudes in the Theta (4-8 Hz) frequency band in the frontal area of the cortex (the warm yellow-orange colors in the middle topograph). Higher than normal amounts of Theta activity in the frontal regions of the brain are a hallmark of problems with attention and her QEEG brain map confirms her physician’s diagnosis of ADHD.
This child’s brain map suggests that EEG neurotherapy treatments should focus on reducing the excessive Theta activity seen in her frontal lobes. A treatment protocol that rewards decreases in the amplitude of 4-7 Hz EEG activity with simultaneous increase of 12-16 Hz EEG activity might be be effective with her.
QEEG Brain Mapping is a procedure that records electrical activity produced within the brain from sensors attached to the scalp. This brain map provides us a baseline to work from while we retrain the brain.
Neurometric analysis aids in a more precise view of subtle brain dysfunction. It provides information about the functional organization and disorganization of the brain and its normal development.
It serves as a basis for identifying variations in brain function that are associated with different types of neurological disorders including Attention Deficit Disorder, Learning Disabilities, Depression, Dementia, Mild Head Injury, Addictions, and Obsessive/Compulsive Disorder.
We use this more objective, accurate and detailed information to create more effective neurodevelopmental training protocols.
Benefits of the Procedure
The QEEG human brain mapping procedure is highly advanced and can offer more information than the typical electroencephalogram (EEG). By having a QEEG done, your brain activity can be compared to a wide database of other "normal brains," helping to determine which, if any, of your brain functions is actually abnormal. QEEG is also helpful in determining which type of medications should be used. QEEG can help to diagnose specific conditions thereby indicating specific treatments. This can help save you time, money, and energy when trying to find helpful treatments.
To book a QEEG assessment or to request more information on the procedure and whether it might be of benefit to you, contact Dr. Horst Mueller, RPsych at Green Apple Health Care 780.425-9468.