Brain waves are a language of the brain and can tell us so much more than we are conscious of. Quantitative Electroencephalography (QEEG) measures brain waves with electrodes on the scalp and then applies mathematical methods to the EEG data, mainly power spectral analyses, to obtain quantitative metrics that are associated with behavioral-cognitive brain functions.
Below are the 5 main brainwave types and what each is associated with:
Physical injury to the brain, such as concussion, disrupts normal flow of electrical impulses in the brain tissue. Similarly, toxic injury, seizure disorder, Alzheimer’s disease, anoxia and brain infection (e.g., chronic Lyme encephalitis) alter brainwave activity. ADD, OCD, anxiety, depression and Learning Disability have distinct brainwave “signatures” as well.
LORETA (Low Resolution Electromagnetic Tomography Analysis) allows viewing of 3-dimentional electrical current sources in the brain. It uses data obtained in the QEEG recording and employs standard MRI atlas images with anatomical Talairach coordinates for 3-dimentional gray matter modeling.
The QEEG and LORETA findings are then compared to a normative database. This database consists of brainwave recordings of several hundred healthy individuals. Comparisons are displayed as Z scores, which represent standard deviations from the norm.
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Baseline, no phone
Phone exposure
Phone exposure with HAVN headwear
The QEEG results are displayed as Z scores, which represent standard deviations from the mean and span from –3 to +3. E.g., a Z score of +2 means that the result is 2 standard deviations higher than the norm. A Z score of 0 represents the norm and is color-coded green. Red and blue colors on the maps show extreme brainwave activity that is 3 SDs above or below the norm. It is important to know that when it comes to brainwave activity, more does not mean better. Both excessive and diminished activity may be equally problematic. SD of 1 is equivalent to being the same as 66% of the population, 2 SD from the mean is more or less brain activity than 95% of the population and 3 is more or less activity than 99.7% of the normative population.
The most studied QEEG metrics are the absolute and relative power in different frequency bands (and ratios of two bands). Neuroscientific literature distinguishes delta, theta, alpha and beta frequency bands and relates them with distinctive states.