Brainwaves: What’s all that (electrical) noise inside your head?

min read

Dr. Mavi Ruiz-Blondet

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Let’s dive into the intricate universe of brain waves—the electrical voices of millions of individual neurons communicating to process all the sensory information you receive and plan the actions you produce. In this article, we’ll explore what brain waves are, how you measure them, and what they can tell us about our mental state.

Where do brain waves come from?

Our brain contains millions of neurons that use electrical signals to communicate with eachother. The messages that are shared between neurons are very simple in isolation, similar to alight switch, but when a large number of neurons start sending and receiving messages inunison, more complex thought and behavior starts emerging.

Interpreting brain waves

EEG stands for electro-encephalo-gram, “encephalo” being the Greek word for brain. “Electro” isthe nature of the signals we are picking up and measuring, and “gram” means drawing (like inthe word: diagram). So EEG is the drawing of the electrical signals from the brain.

Because our bodies are conductive (hence why we shouldn’t put our bare fingers in an electricoutlet) we can pick up these electrical signals from sensors placed on the surface of the skin.

When we put EEG sensors (called electrodes) on the skin around the head, we aren’t “listening” to individual neurons, but to large aggregates of neurons communicating with each other. Ananalogy to this is being outside of a sports stadium, not able to see the game, but able to listento the crowds cheering for their team. So that’s the task of neuroscientists: trying to infer what’s happening in the game by listening to the cheering of the crowd.

One way to do this is to group the signals based on their frequency, and then make guesses about what’s happening in the mind based on those frequencies.

To explain frequencies, we’ll return to the stadium. If we suddenly hear the crowd making a high-pitched sound, we could guess that something surprising or unexpected happened during the game. If we hear a low-pitched sound, we could infer that the crowd is showing disapproval of something they witnessed and are booing as a result.

High and low-pitch sounds made by the crowd are sound waves of high and low frequencies that we can use to deduce what’s happening in the game. Similarly, the electrical signals generated by neurons, the brain waves, also appear in high and low frequencies.

When we put on EEG sensors we can observe brain waves streaming all the time—

*Visual of brain waves streaming from the Neurable lab*

Based on their frequency, we classify the brain waves into one of 5 groups:

How we interpret the meaning of these frequencies when they appear on the EEG depends on the context. For example, when we close our eyes, it is common to generate alpha waves onthe back of the head, where we process vision (the visual cortex). We interpret these brainwaves as our brain routing the incoming information away from the visual cortex, which is notrequired to interpret the information we are receiving when we close our eyes.

What can EEG devices tell us about our mental state?

EEG devices, including the MW75 Neuro headphones, work by putting on a device on the head, which places the embedded sensors against the skin to pick up these electrical signals. These signals are recorded, and then processed by a computer. The presence of different frequency bands in the signals can tell us what is going on in a person’s mind: whether they are asleep or awake, relaxed or tense, distracted or focused, etc.

It’s important to note that these labels are not “the truth”, just like we cannot know for sure what is happening in the game just by hearing the crowds outside. However, they are good estimates of the mental state of a person. Especially when used over time, a person can even understand what their brain waves look like when they are in deep focus vs when they are trying to work butare getting distracted.

The Neurable app integrates with the MW75 Neuro headphones, and can help users get into a state of deep focus faster. Notifications can remind users to take breaks, bring their attention to periods of frequent distractions, and provide suggestions on how they can modify their environment to recharge and clear their mind.

One last thing regarding brainwaves: because they are an electrical signal, we can only pick them up if there is a conductive path between the neuron all the way to the sensor. Most of our body is conductive, to some extent, but there are some exceptions, such as the hair or clothes.Scientific studies get around this hurdle by putting conductive gel on the hair. Our headphones, on the other hand, place the sensors directly on the skin, and as long as there is no hair on the way, then our app is able to listen to your brainwaves loud and clear which in turn allows it to best support you.

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‍²Distraction Stroop Tasks experiment: The Stroop Effect (also known as cognitive interference) is a psychological phenomenon describing the difficulty people have naming a color when it's used to spell the name of a different color. During each trial of this experiment, we flashed the words “Red” or “Yellow” on a screen. Participants were asked to respond to the color of the words and ignore their meaning by pressing four keys on the keyboard –– “D”, “F”, “J”, and “K,” -- which were mapped to “Red,” “Green,” “Blue,” and “Yellow” colors, respectively. Trials in the Stroop task were categorized into congruent, when the text content matched the text color (e.g. Red), and incongruent, when the text content did not match the text color (e.g., Red). The incongruent case was counter-intuitive and more difficult. We expected to see lower accuracy, higher response times, and a drop in Alpha band power in incongruent trials. To mimic the chaotic distraction environment of in-person office life, we added an additional layer of complexity by floating the words on different visual backgrounds (a calm river, a roller coaster, a calm beach, and a busy marketplace). Both the behavioral and neural data we collected showed consistently different results in incongruent tasks, such as longer reaction times and lower Alpha waves, particularly when the words appeared on top of the marketplace background, the most distracting scene.

‍Interruption by Notification: It’s widely known that push notifications decrease focus level. In our three Interruption by Notification experiments, participants performed the Stroop Tasks, above, with and without push notifications, which consisted of a sound played at random time followed by a prompt to complete an activity. Our behavioral analysis and focus metrics showed that, on average, participants presented slower reaction times and were less accurate during blocks of time with distractions compared to those without them.

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