An EEG is a tool to measure and display the electrical activity of the brain. Whether you’re a therapist, a researcher or simply a brain owner, it’s worth understanding what EEGs do and how they work. Why? Because EEGs can show us how to improve our minds.

The more we learn from EEGs, the clearer our roadmap to a better brain becomes.

The everyday relevance of EEG technology can be easy to miss. Most discussions of EEG concern only their diagnostic use in a hospital. We’re going to go beyond that and explain exactly what these devices are, what they can do, where they came from and where they’re going. And how learnings from EEGs can help anyone- even if you never use one directly.


Contents

  1. How Does an EEG Work?
  2. The Invention of the EEG
  3. qEEG vs. EEG
  4. The Significance of Brainwaves
  5. What Can EEGs Do for You?


How Does an EEG Work?

EEGs use sensors placed on the head. These sensors can tell when electrical activity from the brain increases or decreases. When displayed on a screen it looks like a series of waves- hence the term “brainwaves.”

Brainwaves Defined:

“Brainwave” is a term to describe the rhythm created as the cells in your brain communicate with each other using electricity. These cells are called neurons, and your brain contains billions of neurons sending electronic messages at all times.

During this communication, the levels of electricity from these messages in your brain rise and fall like waves. Brainwaves!

So, “brainwave” is the word we use to describe mental activity. What’s most important about this rhythm is that brainwaves are connected to what we’re feeling and doing.

An EEG provides a picture of brainwave rhythm at that moment. A person or machine can look at an EEG reading and count the number of waves per second. That tells them what type of brainwave is present. Here’s one example of how a brainwave type can be measured, and what it means:

eeg-waves-alpha

A little further down the page, we’ll explain what research has revealed about the significance of more brainwave patterns. But first, let’s take a step back and explore the origins of this fascinating technology.


The Invention of the EEG

The EEG came to be because a former soldier set out to prove that telepathy was possible.

His name was Hans Berger. He would go on to be a noted psychiatrist, and be called the “Father of the EEG.”

But in the 1890s, he was an army enlistee who had just fallen off his horse. Days later, he received a letter from his sister, telling him about a dream she had where- surprise- he fell off of a horse. It was dated to the exact day the accident happened.

Berger didn’t necessarily believe that something supernatural had happened. He was aware of recent advancements in science demonstrating that the brain produces electricity. He believed this energy could be transferred between brains, making telepathic communication possible.

Setting out to confirm this belief, he built a device to measure and record electrical energy on the surface of the brain. This was the first EEG device. In 1924, he was able to capture the first recordings of brainwave activity in humans. He called the first wave he discovered “alpha” – after the first letter of the Greek alphabet.

hans-berger-qeeg-eeg

He also found that brainwaves changed when a subject closed their eyes. This was the first evidence that the electrical activity of the mind is directly connected to what we do and think.

The scientific community was skeptical at first that these EEG recordings had any significance. But continued research would propel Berger’s method and invention to wide acceptance. In 1934, British scientists Adrien and Mathews would confirm Berger’s finding that brainwave changes were linked to psychological changes. Two years later, the first EEG lab would open in Massachusetts. And by 1947, an American EEG society was formed.

As you might expect, the EEG technology we use today has evolved many times since Berger’s discovery. One of the more important advancements was the transition to measuring and analyzing brainwaves with qEEG.


qEEG vs. EEG

What makes a qEEG (or quantitative EEG) different from a standard EEG?

The fact is that nearly all modern EEG work is quantitative. Although the term “qEEG” is still used, it could be considered a leftover from a period of transition in this science.

The term qEEG came with the rise of computers. Before that, conducting an EEG recording would involve pages and pages of brainwave data that would need to be analyzed by hand.

As computing technology advanced, it became possible to record more data and process it more quickly. As that change was ongoing, scientists and therapists needed to note the difference between advanced “qEEG” work and limited “EEG” work.

Think of it this way- an EEG measures one factor, while qEEG measures many factors.

With a standard EEG, only the speed of brainwave activity is being measured. For example, an EEG sensor may detect 10 waves per second, so we know that “alpha” activity is present.

Yet that alone doesn’t tell us that the subject is in a calm, relaxed “alpha” mental state. In reality, there are multiple speeds of brainwaves happening in different areas of the brain at all times.

A qEEG helps us get a better grasp of this. They show us things like how much electrical energy is powering a given brainwave type, and how active that brainwave type is compared against others.

qEEG is a more complete, mathematical and accurate look at what is happening in the brain.

So, there’s no longer a difference you need to be aware of between “EEG” and “qEEG.” The key takeaway is that modern EEG is about detecting the brainwave type that’s most powerful at a given time. When we know that, we get a significant insight into what a person is doing or feeling.


The Significance of Brainwaves

Decades of research powered by EEGs have enabled neuroscientists to identify different types of brainwaves, and understand more about the meaning behind them.

There are 5 common categories of brainwaves, and each is identified by the number up/down wave cycles measured per second. Here’s what we know about the effects when each of these 5 types is the most active in the brain.

Delta – 0 to 3 waves/second
Delta is the slowest brainwave type, and is dominant during deep, restorative sleep. High levels of delta during sleep shows a deeper, more stable sleep state (Botella-Soler, 2012).
Theta – 3 to 8 waves/second
Light sleep or extreme relaxation. Experienced meditators demonstrate higher theta power during their peak practice, in very tranquil states with almost no “mental chatter” (Cahn, 2006).
Alpha – 8 to 12 waves/second
Relaxed wakefulness. Mental states dominated by alpha are commonly described as calm and pleasant- sometimes accompanied by a “floating” feeling (Pavlenko, 2009).
Beta – 12 to 27 waves/second
Wide awake. Higher beta power is linked to emotional stability, increased energy levels, and focused states of extended concentration (Alhambra, 1995)
Gamma – 27 or more waves/second
Gamma is associated with the formation of ideas, memory processing and learning (Miltner, 1999). Humans and apes are the only living creatures that produce gamma waves.


What Can EEGs Do for You?

EEGs are an incredible tool to better understand the human mind. With them, we can see what patterns lead to feelings of anxiety and unease, and steer away from them. Or see the brainwaves that appear during calm, focused thinking, and try to boost those.

The more we learn from EEGs, the clearer our roadmap to a better brain becomes.

Anyone can take action on this knowledge gained from EEGs about helpful brainwave states, even without undergoing a personal EEG scan.

How? With a method called audio brainwave training.

With this technique, audio sessions are played that have been proven, via high-grade EEG research, to induce dramatic changes in brainwave activity. For example, producing more alpha activity to help someone enter a calm, relaxed state.

Ready to learn more? You can get all the details, and then dive in to try audio brainwave training for yourself, with our Beginner’s Guide to Binaural Beats.

About the Author:

Resources to learn more about EEGs

Scanning the Brain – PBS.org

Portable Brain-Scan Headsets: 4 Incredible Applications – National Geographic

OpenEEG Project


References:

Alhambra, Marabella A., Timothy P. Fowler, and Antonio A. Alhambra. “EEG biofeedback: A new treatment option for ADD/ADHD.” Journal of Neurotherapy 1.2 (1995): 39-43.

Botella-Soler, V., Valderrama, M., Crépon, B., Navarro, V., & Le Van Quyen, M. (2012). Large-scale cortical dynamics of sleep slow waves. PloS one, 7 (2), e30757.

Buzsaki, G. (2006). Rhythms of the Brain. Oxford University Press.

Cahn, B. “Meditation States and Traits: EEG, ERP, and Neuroimaging Studies.” Psychological Bulletin 2006, Vol. 132, No. 2, 180-211.

Miltner, W. H., Braun, C., Arnold, M., Witte, H., & Taub, E. (1999). Coherence of gamma-band EEG activity as a basis for associative learning. Nature, 397(6718), 434-436.

Pavlenko, V. B., Chernyi, S. V., & Goubkina, D. G. (2009). EEG correlates of anxiety and emotional stability in adult healthy subjects. Neurophysiology, 41 (5), 337-345.

Swartz, B. E. (1998). The advantages of digital over analog recording techniques. Electroencephalography and clinical neurophysiology, 106(2), 113-117.

(Our full list of research conducted in this field can be found here.)

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