QEEG vs EEG – What’s The Difference?

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Image of a QEEG brain scan beofre neurofeedback therapy

Written By: Dr. Starr

Dr. Starr is a medical doctor, psychiatrist and computational neuroscientist who has been active in Brain-Computer Interface and Neurofeedback since 1990.
To learn more about neurofeedback, please read the article; What Is Neurofeedback. If you are interested in home neurofeedback please read the article; Neurofeedback At Home.

QEEG vs EEG – What’s The Difference?

To understand the difference between an EEG and a QEEG please learn about both an EEG scan and a QEEG scan below.

What is an EEG or EEG Scan?

An EEG is an acronym or abbreviation for Electroencephalogram. The word electro comes from Latin via Greek Mythology. Elektra was the daughter of King Agamemnon and Queen Clytemnestra from Greek Mythology, and her name translates to the word for Amber.

Sir Francis Bacon first popularized it in Pseudodoxia Epidemica written in 1646 and used to describe Amber’s nature to attract using static electricity from other charged objects. This is how we have our current word for electricity. Encephalon is also from the Greek language and means “the head” or the “brain.” Gram is the Greek word for a measure or tiny. If we put all these together, we get a piece of technology that measures electrical activity from the brain

The EEG measures are recorded as waves, meaning they have magnitude and direction. These waves are interpreted by an expert who can determine various states of disease in the brain.

Image of an EEG scan shown in wave format.

The EEG measures are recorded as waves, meaning they have magnitude and direction.

Furthermore, electroencephalography (EEG) is the measurement of electrical patterns at the surface of the scalp which reflects cortical activity. These electrical patterns are commonly referred to as “brainwaves”.

What is a QEEG or QEEG Scan?

Quantitative EEG (QEEG) is the analysis of the digitized EEG, and in lay terms, this sometimes is also called “Brain Mapping”.

The Q in QEEG refers to Quantitative. Quanta, or in the singular tense, Quantum, is a fundamental measurement of the smallest unit of a given set of items. To take a QEEG means that the EEG is recorded and broken up into numbers computed to determine the brain’s functioning.

QEEGs require powerful computers and complicated mathematical algorithms to assess the brain’s functioning on a nanosecond by nanosecond basis. The QEEG process allows the professionals at Myneurva to create a brain map through this combination of precise measurement and quantitative comparison.

The QEEG uses a mathematical algorithm called the spectral analysis or Fast-Fourier Transform to compute voltage over frequency for the brain’s key areas. The FFT produces a function in which micro voltage is plotted over frequency.

Image of a QEEG brain scan before neurofeedback treatment.

A QEEG analysis and visual representation of an ADHD Brain scan.

This function, or FFT, is compared to a database that has been statistically normed to a population via a Gaussian distribution and Z-Score. Simply stated, if a known area of the brain differs from a given Z-Score by greater than 2 Sigma, it can be concluded that an individual has a performance enhancement or deficit based on the comparison database.

If you have any questions about the difference between a QEEG and an EEG please contact Myneurva today!

Credible Research on EEG and QEEG