Introduction to Raw EEG
How Do We Measure Brainwave Activity?
So you want to learn about what is happening in your brain do you? Well, unlike your eyes, ears, legs and arms, we cannot see what is happening inside of your brain at any moment in time. What can we then use to visualize the activity in your brain?
As you may have already learned, there are constant electrical signals being fired in your brain 24 hours a day, 7 days a week, every day of the year. The billions of neurons inside of your brain develop enough electrical activity to be measured by special sensors that researchers can place on your scalp. No crazy surgery or sci-fi movie technology required! Just like your cell phone can detect how much power is inside of its battery, we can use these sensors to detect the strength of electrical activity inside of your brain.
This technology is called Electroencephalography, or something much easier to say, EEG. EEG is a system of placing sensors called electrodes on different places on your head which measure these constantly changing electrical signals. EEG is a biomedical measurement technique that has been used by researchers, doctors, brain computer interface scientists and hobbyists to observe and evaluate the brain activity of patients and research partners. You are on your way to becoming a brain computer interface expert by starting with EEG!
Before you have to ask, no EEG cannot read your mind and no EEG will not “shock your brain”. What EEG can do though is measure how very large groups of neurons in your brain are acting. By measuring this activity and comparing it to some scientific knowledge we will learn, we can make some judgments about your mental state. These include things like measuring how focused you are, how relaxed you are, and other cool discoveries.
Wait EEG? I thought we were learning about BCI?
Yes, EEG is one of the simplest ways to construct a brain computer interface system! To develop one of these systems, you need to have one device collect information from the brain, another device analyze that information and then finally, a third device do something with the information.
EEG technology has actually been around for about 100 years. If you have ever seen pictures of a person wearing a headset with lots of wires connecting to a machine in the hospital, this was likely an EEG device. Thankfully, technology has improved very much over the decades and much of this same information can be measured through the device you have on your head.
What you see in your “Raw EEG” reading are the signals the sensors on your headset are detecting that have been changed into waves. The spikes in these lines form the building blocks of the other 4 graphs that are on your NeuroMaker Connect interface. We will be learning much more about those in the future so stayed tuned!
So What Can I See with My Data Right Now?
Remember, EEG is measuring electrical activity detected through the sensors on your Focus1 headband. Anything creating an electrical signal will be detected. This is typically intended to be the neurons firing inside of your brain, however other things can also be caught in these sensors. Believe it or not, these sensors are sensitive enough to pick up electrical signals coming from the wires inside of your house.
Although we will mostly be studying the signals coming from your brain in the NeuroMaker BCI curriculum, there are also other electrical signals that you can pick up from your head with your headband. Every time you move a muscle in your body, there is a small electrical signal that travels through the nervous system to special neurons connected to your muscles that can be detected. Therefore every time you flex the muscles in your forehead, move your eyebrows up and down, blink your eyes, or move any other muscle on your head, you are generating electrical signals that you Focus1 headband can detect!
These muscle signals are called artifacts. Artifacts are signals recorded and shown on the Raw EEG plot, but are tied to motion of the subject, not the electrical activity of the brain. Although we are going to spend a lot of time in NeuroMaker BCI trying to remove these signals from our data, right now they are a great way to visualize real time activity coming from your head right now.
One of the easiest EEG artifacts to observe & recreate are eye-blink EEG artifacts. If you blink your eyes, you can see high amplitude spikes appear in the Raw EEG plot. Give it a try and see if you can detect an artifact live through your data!
The Role of Raw EEG Signals
The eye blink or eyebrow movement signals you have seen in your NeuroMaker Connect line graph probably is a little hard to make out. The main reason behind this is there is a LOT of activity being measured by the electrodes on your headband. In a matter of fact, hundreds of pieces of data called samples are recorded and presented to you on your BCI Connect interface every single second. Using raw data alone is very, very difficult, if not impossible, for a human to view and make sense of for any meaningful BCI or neuroscience problems that we want to solve.
Although viewing this data with the human eye second by second is not very useful, a computer will have no problem analyzing these signals and making sense of them for us. Through the NeuroMaker BCI curriculum, we are going to learn step by step the neuroscience, programming, machine learning and other tools necessary to turn these complicated pieces of data into systems that we can understand. We don’t want to prevent you from jumping right into this yet, through and have already assembled three different prepared algorithms for you to use right now.
The Raw EEG data is filtered and processed to generate the brainwave, attention level, and meditation data shown in the rest of the BCI Connect software. You can think of the raw EEG data as the building blocks of all of the other data on your screen. Behind each of the other pieces line and bar graphs in your software, there are thousands of calculations every second turning the raw EEG data into an attention, meditation, alpha and other plots. As a BCI student, it will be your adventure taking this raw EEG data and unlocking the information it holds.