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 averaged over a time period, and in lay terms this is often called “Brain Mapping”. The QEEG is an extension of the visual raw EEG analysis which assists and increases our understanding of the EEG and brain function
In practice, a QEEG involves placing a 19 channel electrode “cap” over the client’s head which captures the EEG recording and sends it to a computer. Once the cap is fitted and the signal is clear, a 10 minute ‘Eyes Open’ condition, followed by a 10 minute ‘Eyes Closed’ condition is recorded. This multi-channel EEG data is processed with various algorithms for example, “Wavelet” analysis enables the clinician to see amplitudes of specific frequency bandwidths. The digital data is statistically analysed, comparing values with “normative” database reference values. The processed EEG is commonly converted into colour maps of brain functioning called topographic “Brain” maps.
The EEG and the derived QEEG information can be interpreted and used as a clinical tool to evaluate brain function, and to track its changes due to various interventions such as Neurofeedback therapy or medication.
Processing Speed Analysis
Quantitative Electroencephalography (QEEG) processing techniques and the use of modern analytic software to process the EEG/ QEEG, also gives us the ability to view the dynamic changes taking place throughout the brain during cognitive processing tasks. This novel approach can be used to assist us in determining which areas of the brain are well engaged and processing information efficiently, by comparing the Evoked Potentials (event related potentials) of the client to a normative database.
Evoked Potential studies are based on a similar principle as the QEEG studies except, in this case, we challenge the brain to respond to specific environmental challenges. For example, we may ask the brain to detect differences between sounds, respond to mild stimulation of the hands or feet, or watch the brain as it solves problems. These tests help evaluate the integrity of systems allowing the clinicians to determine how well the brain performs basic functions. For example, aberrant response to the auditory processing test will lead the clinician to focus on this system first.
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.
At the Listen And Learn Centre a QEEG assessment is used to assist in the diagnosis of disorders and assist in establishment of intervention protocols.
The Listen And Learn Centre is one of a handful of clinics in Melbourne that has QEEG Assessment tools available to test brain function.
Autism Diagnosis using QEEG brain scans
Researchers remark that a major challenge that comes with assessing autism spectrum disorder that is that there’s no “objective” way to diagnose the diseased based on biomarkers — that is, to say, “Well, his levels of X were very high, so we he definitely has ASD.” Instead, clinicians have to rely on behavioural assessments that can be subjective. A recent study from Albert Einstein College of Medicine researchers, used QEEG brain scans as a step towards better diagnosing ASD.
From the press release:
Forty-three ASD children aged 6 to 17 were presented with either a simple auditory tone, a visual image (red circle), or a tone combined with an image, and instructed to press a button as soon as possible after hearing the tone, seeing the image or seeing and hearing the two stimuli together. Continuous EEG recordings were made via 70 scalp electrodes to determine how fast the children’s brains were processing the stimuli.
According to the researchers, there was a strong correlation between the amount of time it took participants to process auditory (but not visual) signals and the severity of their ASD symptoms. “This finding is in line with studies showing that, in people with ASD, the microarchitecture in the brain’s auditory centre differs from that of typically developing children,” said lead author Sophie Molholm in the release.
In an email to Science of Us at NYMAG.com, Molholm expanded: Our work shows that measuring brain activity with EEG has great potential for use in the diagnosis of autism.
Some of the research that we plan to pursue includes using these biomarkers to test whether targeted therapeutic interventions regulate sensory processing and improve multisensory integration in autism; testing if these biomarkers are applicable in even younger children with autism; and measuring the relationship of additional EEG measures of brain function and symptoms of autism.
The Listen And Learn Centre has the technology to undertake brain scans using QEEGs and ERPs tools to study Autism and ADHD biomarkers. The centre also undertakes pre versus post intervention brain scans to demonstrate the efficacy of the interventions undertaken at the Centre including Neurofeedback, Auditory Training program and Cellfield interventions.