Electroencephalography (EEG) is the measurement of electrical patterns at the surface of the scalp which reflect cortical activity, and are commonly referred to as “brainwaves”. Quantitative EEG (qEEG) is the analysis of the digitized EEG, and in lay terms this sometimes is also called “Brain Mapping”. The qEEG is an extension of the analysis of the visual EEG interpretation which may assist and even augment our understanding of the EEG and brain function.
Quantitative Electroencephalography (qEEG) is a procedure that processes the recorded EEG activity from a multi-electrode recording using a computer. This multi-channel EEG data is processed with various algorithms, such as the “Fourier” classically, or in more modern applications “Wavelet” analysis). The digital data is statistically analyzed, sometimes comparing values with “normative” database reference values. The processed EEG is commonly converted into color maps of brain functioning called “Brain maps”.
The EEG and the derived qEEG information can be interpreted and used by experts as a clinical tool to evaluate brain function, and to track the changes in brain function due to various interventions such as neurofeedback or medication.
Quantitative Electroencephalography (qEEG) processing techniques and the use of modern analytic software to processes the EEG/qEEG gives us the ability to view the dynamic changes taking place throughout the brain during cognitive processing tasks, and this novel approach can be used to assist us in determining which areas of the brain are engaged and processing efficiently.
Various analytic approaches exist, from commercial databases to database free approaches, such as EEG phenotype analysis or the more classic European Vigilance model of Bente (1964) are used in modern clinical application of the EEG/qEEG. The use of advanced techniques such as Independent Component Analysis (ICA) and neuro-imaging techniques such as Low Resolution Electromagnetic Tomography (LORETA) can map the actual sources of the cortical rhythms. These advanced approaches are changing our understanding of the dynamics and function of the human brain.
Introduction to qEEG based Neurofeedback
It is presumptuous to think that the fields of qEEG and neuro-feedback (NF) are advanced far enough to have a scientifically qEEG based protocol that is a hard and fast rule. The field is scientific, but it is a scientific art at this time to use a qEEG to design an intervention. It is entirely foolhardy to make rules for this artistic task, so that is undoubtedly why I was approached for this task.
An effective intervention into any system is to introduce feedback of the signal to be changed into the system This allows the system to self regulate, like the heating or cooling system in a house as a simple analogy. The models of how this works vary from systems theory, to anatomical/structural models, learning theory, even non-linear dynamics or “chaos theory”.
The organic models have some measurable validity, with the observed expansion of cortical areas dedicated to the structures utilized in tasks. Another observation supporting this model is the dendritic density increase in the cortex utilized in learned tasks. There are even reports recently of memory or ‘long term potentiation’ being predicted by the electrophysiologic brain state measured at the time of the perception to be recalled (Wagner et al., Science, August 1988)
The learning theory models have learning curve data to show the stages of the acquisition of the skill of volitional control over the autonomic activity with NT. They also predict the effect on efficacy of the sessions’ scheduling to shorten the total treatment times; massing the initial sessions and stretching out the later session’s intervals.
The systems theorists suggest the mere introduction of feedback may initiate self regulation. This is seen with the audible heart beat normalizing the inter-beat interval, without any instructions to the subject.
The most controversial systems theory being the “chaos” theoreticians, who vary in opinion. Some chaos theoreticians in this field will say the anatomically specific electrode site selection in NF is irrelevant ( Brown et al., 1998 SSNR), with others saying the site selection is critical for optimizing the training in NF (Thatcher, personal communication 1998). Some theoretical discussions even state that the purturbation of the system from feedback acts to chaotically restabilize the system independent of the need to follow out a learning curve of further treatment,
just expose the system to the chaos of feedback and that is all that is needed (Schore, 1997).
The bottom line is they all are theories, or perspectives with testable hypotheses associated with them. Many theories are not mutually exclusive of others, so the research proceeds with various, sometimes mutiple perspectives. The complexity and diversity of the models and opinions attests to the interdisciplinary nature of this field.
The most conservative critics would suggest placebo effect and experimenter effects as the sole forces at work in NF. This too is a testable hypothesis, one which is having an increasing difficulty explaining the observed results of the research found in peer reviewed publications.
There are many in the field of Neurotherapy who do not perform qEEGs prior to designing a clinical intervention. These people are currently practicing well within the standard of practice for this rapidly evolving field. Many within this group have standard protocols which are used on all clients, with various alterations to respond to the client’s reported experiences during the treatment.
I see the field of NF gradually moving more toward the use of qEEG, but it is not required by any stretch of the imagination, much less a standard of practice. I am sometimes misquoted as having said it is unethical to do neurofeedback without a qEEG. It may be less than optimal, in my estimation, but it is certainly not unethical.
The argument has been raised that the qEEG is only a way to bill the client additional charges, draining the vital cash reserves of the clients, with no scientific evidence of a benefit for the use of the qEEG. I agree there is an expense for a qEEG. To routinely perform a qEEG without a demonstrable treatment benefit would be difficult to justify.
There is an increasing body of evidence that there is a positive treatment impact from the use of a qEEG and the resultant customized NF intervention. The initial information coming from those using the technique “feeling” they got some clinical utility from qEEG data. The more persuasive evidence to date is a retrospective evaluation of outcomes in a single practice.
The retrospective research compared 3 years of NF data using a commonly used standard treatment approach to 2 years using the qEEG based customized intervention. A gross summarizing of the paper shows a doubling of the consevatively estimated clinical success, from 30 to 60%. Further, the total treatment benefit (both ‘some benefit’ and ‘full’ benefit groups added together) increased from the commonly previously reported 80% increased to 90% now receiving perceived benefit (C. Wright et al., SSNR, Austin 1998).
The cost effectiveness is seen easily if there are a few sessions spent “getting it right” using the clinical guesses to select sites. It only takes a few wasted sessions, not to mention possible adverse reactions, to pay for the proper selection using the qEEG.
I believe the strongest argument for the use of qEEG stems from the reported incidence of non-convulsive frontal and temporal lobe epilepsy comorbid with diagnosis of ADD/ADHD. When I saw 10% quoted in the literature, I was shocked and had some doubts about the reliability of the observation. Following nearly 3 years doing the screening for one ADD/ADHD practice, I saw a similar percentage of undiagnosed or “occult epilepsy”. I now have more faith in the figure.
To use a standard ADD/ADHD intervention with an undiagnosed epileptic may be problematic. The lack of awareness being no excuse (read ‘defense’) if legalities are invoked. The qEEG has a clinical EEG read during its evaluation, allowing for the proper referal or diagnosis of epilepsy (or any other occult condition such as tumor, metabolic or toxic encephalopathy or early dementia).
I once heard qEEG referred to as “electro-phrenology”, a term that conjures up images of ancient times and archaic beliefs about brain function. I sort of like the term, as I think the term speaks to the potential to make simplistic assumptions about intervention, based on colored map “hot” spots, the ‘bumps’ of electro-phrenology.
QEEGers without an appropriately sophisticated model of how the brain works will be tempted to stick the intervening electrodes on areas that ‘light up’ with some color in a map. The area is likely to be an artifact, a normal finding, a normal variant or even the proper area for intervention. It may also be an effect of a distant cause or change in brain regulation.
The time consuming study of the brain’s function, EEG and the quantitative analysis techniques, including artifacts is needed to understand the colorful and informative mappings, tables of values and database comparisons. The careful study of the database selected is also needed to understand its strengths and weaknesses (Thatcher, 1998).
One of the earliest NF clinicians to use the qEEG to intervene in the 1970’s was Pourier, a Canadian clinician/researcher. He used the Fourier analysis derived compressed spectral array (CSA) to select the ‘deficient’ bands and those in ‘excess’, setting his protocol to act like a bull dozer, chopping off peaks and filling in valleys. His clinical judgements were based on experience, not database comparisons, but he did report positive results clinically.
Hopefully qEEG based NF has advanced since these early days of simplistic assumptions and electro-phrenology. For now, the study of the digital manipulations of the data needs to be put in place.
Entering into the field of qEEG, one should expect to have a huge continuing education opportunity and responsibility ahead. I would advise the initial study of EEG to anyone entering this field, as it is the basis of the technique. Studying EEG allows for a solid foundation for the later study of qEEG methods and clinical applications.
Some certification in the field of EEG, or basic course completion in EEG should precede any entry into qEEG. The field of qEEG does not have any legislated requirements in California, though certification exists for various levels of practice in this area. Certification or licensure is regulated on a state-by-state basis.
The medical professional should proceed to board certification in EEG, then the qEEG specialization. This has been available from both the American Board of Electroencephalography and Neurophysiology (ABEN, AMEEGA’s associated testing board) and American Academy of Neurologies (AAN) affiliated testing bodies for EEG, but only ABEN for the quantitative EEG specialization.
Psychologists have had the American Psychiatric Electrophysiology Association (APEA) for education in the field, however, now the APEA and AMEEGA merged in 1998 to form the EEG and Clinical Neurosciences Society (ECNS).
This combined body will offer the board certification previously available to medical doctors through an associated testing board, ABEN.
I must disclose an association with technologist educational and testing groups, the AAQEEG and ABCQEEG boards, offering training seminars in EEG and qEEG and certification as a QEEGT. This certification is not required to practice anywhere, but does show a demonstrated competence in the technique of qEEG. Testing should not be attempted without substantial investment in studying the details of the technique, as the low pass rate would attest.
There is also the issue of regulatory approval for equipment, both in EEG/qEEG and in NT. The FDA has regulatory authority over NF and EEG devices that are sold or marketed, including NF devices, qEEG hardware and software… even databases. The FDA does not approve devices, it registers them, after they have gone through an arduous regulatory review for the validity of the claims and the safety and efficacy of the device.
The FDA registration has been cleared by many manufacturers, though there are some who continue to try flying beneath the regulatory ‘radar’. The equipment purchased by an end user that is not federally approved may be ‘taken’ without compensation by the FDA. As you can see, there is a benefit to looking for the FDA 510K number before purchasing any hardware or software.
Individuals interested in workshops and conventions in the field of NF and qEEG should look at AAPB (www.aapb.org) and ISNR (www.isnr.org) and local organizations and interest groups are often available as well.
The qEEG is used by those currently in a professional practice for the following clinical applications: evaluating effects of medications and predicting medication response, evaluating head traumas, assessment of cognitive and psychiatric changes, in NF and in peak performance assessment and training as well as others.
The use of qEEG ‘dipole location’ in surgical candidate assessment befor brain surgery in epilepsy is one of it’s most solidly accepted areas, with AAN approval. In other areas of qEEG application there are various levels of support or lack thereof from the various professional groups.
In the hands of those familiar with the field, qEEG can be used well in all these areas. In the hands of someone unfamiliar with the details of the technique, it can be a waste of time, a source of distraction or difficulty or even a liability.