Quantitative Electroencephalography


The QEEG is an assessment procedure which provides a detailed examination and statistical analysis of the patterns of brain activity revealed by the EEG. The information derived from the QEEG is used in neurofeedback to help identify the areas of the brain as well the functional characteristics of brain activity that are targets for training. The information from the QEEG is evaluated along with other data gathered during the assessment process prior to beginning treatment.

The Basics


A cloth cap with 19 electrodes is placed on the head and conductive gel is used to carry the EEG signal from the scalp to the electrodes. Data is recorded during resting states of eyes open, eyes closed, and in some instances during challenge tasks such as reading or solving math problems. Approximately ten minutes of data are recorded in each state. A QEEG typically requires about an hour total in the office to complete gathering necessary data.

The data recorded at the Midwest Neurofitness office is transmitted electronically to a clinical facility for specialized expertise analyzing and interpreting this data. The processed data and a summary report are provided by this interpretive service. The time from recording to completion of analysis is typically four working days.

Preparation for the QEEG:

1. The night before your QEEG wash your hair

twice with a nonresidue shampoo. Neutrogena

is recommended.

2. Do not use any conditioner, gel, or hair spray.

3. Do not take stimulant medication within 15 hours

of your QEEG if possible.

4. Do not take any medication that may have a

sedative or stimulating effect such as allergy

medicine or aspirin with caffeine.

5. Do not take any nutritional supplements that might

contain ingredients which have a stimulant effect.

6. Try to get a good night’s sleep the night before.

7. Try to eat a meal within a few hours before your

QEEG. If you normally drink coffee or have a

caffeinated beverage during the day just follow

your normal routine.

8. The procedure should take approximately one

hour including preparation and recording.

9. Please have a list of any medications that you are

taking such as antidepressants, anticonvulsants

(epilepsy medications) or anxiolytics (anti-anxiety

medications) that might affect the QEEG.

10. Also provide any history of head injuries, tumors,

strokes, or brain surgery.

More Information

Than You Might Want to Know

Traditional interpretation of the EEG is done visually by a trained specialist such as a neurologist. The neurologist will examine the EEG, which looks much like the jagged edge of a saw blade, to identify certain characteristics in the brain waves that might indicate epilepsy or some other abnormality. In the quantitative EEG process the brain wave activity is recorded digitally then this digitized data is subjected to statistical analysis. Although efforts were made to use quantitative analysis of the EEG as far back as the 1930’s, it wasn’t until the advent of personal computers and advancements in software that the QEEG became accessible to most clinicians.

After recording the EEG data it is edited to remove ‘artifacts’ which are distortions in the EEG signal due to movement, muscle tension, pulse and other sources. During the editing process the data is examined visually to identify any patterns that might be of interest for training purposes or would suggest the need to refer to another specialist.

After the editing process is completed the data is subjected to a variety of statistical analyses. The final analysis is the database comparison. This procedure allows for an individual’s EEG to be compared to an ‘average’ EEG. This comparison data is derived from the analysis of EEG’s gathered from hundreds of individuals; same sex, same handedness, approximate same age; who do not exhibit or report historically any significant mental health issues. Often the EEG will be compared to multiple databases.

The aspects of an individual’s EEG to be analyzed by the QEEG are:

1. Does the individual’s EEG differ from the 'average’ EEG to a level of statistical significance?

2. Where (what areas of the brain) does it look different?

3. How (what functional characteristics) does it look different?

The QEEG allows for the examination of many characteristics of brain activity. The characteristics used most often for neurofeedback training are:

Absolute Power

How does the amount of brain activity measured at different frequencies compare to similar individuals?

Relative Power

How does the proportion of the brain activity distributed across the frequency spectrum compare to the distribution in similar individuals?


How well are different areas of the brain working together? Coherence and comodulation are measures of similarity in

brain wave patterns between two different areas.


How well are high-low frequencies balanced across hemispheres of the brain as well as from the front to the back of the brain?

Low Resolution Brain Electromagnetic Tomography-Loreta

The Loreta provides a 3-D analysis of the EEG identifying localized disruptions in brain activity within the interior of the brain. Stroke, tumors, and other lesions are the most common sources of these disruptions.

Discriminant Analyses

The two Discriminant Analyses, one for Traumatic Brain Injury (TBI), and the other for Learning Disabilities (LD) utilize all the characteristics examined by the QEEG. Those factors that are consistent with a history of TBI and LD are examined to produce a statistical probability of those diagnoses. The TBI analysis is based upon data gathered by the Department of Defense and the Veterans Administration. Both analyses were developed by Dr. Robert Thatcher.

The QEEG data is used to generate a series of statistical analyses presented in table and graphic for in brain maps. An individual who has received specialized training in the interpretation of the QEEG examines both the raw EEG and these results. That individual will generate a summary report which is provided to the neurofeedback practitioner to help guide the training process.

Current applications of QEEG

Prior to the use of the QEEG for purposes of neurofeedback training the QEEG was used primarily in research. Due to the non-invasive nature of the procedure, the convenience, low cost, and specificity of the data the QEEG has been used extensively to examine a variety of aspects of brain function. Applications to medical practice have been extremely limited. Consequently few medical personnel have significant experience or knowledge of the procedure.

There are a variety of potential applications for medical purposes. Research has been conducted to investigate the use of QEEG to predict response to psychotropic medications. For example certain patterns of activity might indicate that a specific type of antidepressant medication might be more effective than another. Further, it could be used for pre and post analysis of a pharmacological intervention. Routine utilization of the QEEG as a component of a psychiatric diagnostic procedure would appear to be invaluable.

Forensic applications of the QEEG show great promise. A recent court decision substantiated that the QEEG process has met the requirements of scientific rigor sufficient to be introduced as evidence for the determination of the presence of brain injury. In some cases experts have testified in court regarding patterns of brain activity predisposing an individual toward impulsive violent offenses. Research has also been conducted examining the potential of QEEG as a ‘lie detector’.

Marketing research has utilized the QEEG to monitor patterns of brain activation during exposure to commercials. Increased activation in specific areas of the brain is correlated with desirability leading to greater marketing success. It is evident that use of the QEEG will expand to include many areas of health

care as well as education and commerce.