What are Brainwaves?
The human brain is most likely the most complex system known in the universe with a huge network of nerve cells that are constantly sending information back and forth. Whether you are in a deep sleep, talking to a classmate, or eating food your brain is bustling with activity. Billions of neurons never cease to send small electrical charges through nearly uncountable connections to process memories, activate your muscles, control your mental state and keep yourself functioning.
Although the source and collection of these electrical signals can be a little complicated, all of this activity can be organized into patterns. In fact, the firing of neurons in different groups ends up producing a repeated cycle of activity which can be measured as a brainwave. Scientists have been able to recognize that different brainwave patterns can tell us all kinds of medical and mental information about ourselves. Each one of these brainwaves give us a little insight into how we are feeling, performing or healthy we are while doing certain activities.
The Five Main Brainwaves
Brainwaves are like a series of different musical sound waves that continuously “play” at different high and low pitches. When a part of the song in your brain sings at a high pitch like a soprano, this tells us something about your mental state. Similarly, when we hear the low bass notes of our brain song, we know that something different is happening in your brain. We can pretend that your brainwaves are like a big symphony and that when different groups of our symphony get louder or softer, we know that something is happening.
In our brain symphony, we can divide our orchestra into five different groups: Delta, Theta, Alpha, Beta and Gamma. Each of these groups in our orchestra each have a unique sound which in this case are determined by frequency measured in Hertz (Hz).
To understand these differences, we can look at the diagram above. You can see that each of the five groups are all waves. Just like the waves you seen in the ocean, there are tops of waves that move down and then up again. One way to separate these waves is by looking at how many times they repeat their up and down motions over a period of time. The Hertz unit we mentioned above measure how many wave cycles, that is how many tops of one wave to tops of the next waves, we see in one second. A wave that is four Hertz will have four visible wave tops in one second. A wave that is thirty Hertz will have thirty visible waves in one second.
Looking at the chart above you will see that each colored wave has a different number of wave tops. Assuming each of these waves is happening over the same period of time, the more “squiggly”, meaning closer together wave tops, will have a higher frequency and thus higher Hertz number. The more “smooth” a wave is, meaning the tops of the waves are farther apart, means it will have a lower frequency and thus lower Hertz number.
Now we know how our brainwave orchestra is divided! Just like a real orchestra, sometime the trumpets play very loud making us feel motivated and engaged while the drums beat softly giving us a beat. Other times the violins softly play giving us a sense of relaxation while a singer in the orchestra becomes louder and brings our focus back. This is just like how the brain and the brainwaves we can visualize opereate. Instead of using our orchestra analogy, we can now say that each of these groups are the five main brainwaves below and their volume is what we will call amplitude. The louder a certain section of our orchestra plays will be just like saying how high the amplitude of a certain brainwave extends.
With this knowledge in mind, let’s see what the amplitude of each brainwave mean and how we can use them!
What Our Brainwaves Tell Us
*Please note: the frequency in hertz of each group may differ slightly depending on how they are being used.
0.2 – 3 Hz
Delta waves are the “smoothest” waves in this group, meaning their wave tops are farther apart and thus have a low frequency. Seeing activity happen in this group is typically correlated with sleep, abstract thinking, some kinds of brain injuries and sleep deprivation. If the amplitude of our delta waves is very high, this might mean that the user has sleep deprivation and in special cases might be connected with different kinds of brain injuries. On the other hand, if the amplitude of delta waves is very low, this may mean that there could be signs of sleep disturbances, ADHD or anxiety. We won’t be using delta waves very often in NeuroMaker BCI, however they can unlock some very interesting facts about the deeper actions of our brain!
3 – 8 Hz
Theta waves have a higher frequency than delta waves and are commonly connected with activities like daydreaming. Depending on where in the brain these waves come from and their amplitude, theta waves are associated with activities as diverse as creativity, spontaneity, inattention and depression. Researchers have found that theta waves tend to be higher in children than adults, which suggests that these waves are closely related with brain maturity. Interestingly, theta waves are also present in temporary loss of memory from older individuals with a special name called BORTT, standing for “burst of rhythmic temporal theta.”
Alpha waves sit in the middle in terms of frequency and amplitude. They become dominant during states of physical & mental relaxation. Alpha waves aid overall mental coordination, calmness, alertness, mind/body integration and learning. Alpha waves are some of the most commonly studied brainwaves, which have some special considerations with eyes opened or closed which we will dive into more detail below. As a general rule, the more powerful your Alpha waves are, the more relaxed, at peace and not mentally engaged you are.
12 – 27 Hz
Beta waves are dominant when you are awake, alert, and engaged, and are probably the predominant waves observable if you go to the doctor to get an EEG reading. Beta waves are most visible when you are focused, analytical, externally oriented or in state of relaxed thinking. Beta waves are commonly used to detect conditions such as sleep and learning disorders as well as to study enhanced focus. For all BCI hopefuls beware! Beta wave frequencies overlap with the muscle signals created by clenching your jaw. If you clench your jaw while viewing your NeuroMaker BCI Connect readings, you will notice greater Beta wave activity. For this reason, it is important for anyone using EEG devices to relax while they view their Beta wave information.
27 – 100 Hz
Gamma waves have the smallest amplitude and highest frequency; they pass information rapidly and quietly. They are observable in states of deep focus, like when studying math or problem-solving. Gamma waves are activated when the brain needs to be active and idle when no specialized task is at hand. Top level athletes and high performers often train with gamma wave readings because these promote learning and memory from long distance brain connections. Just like we mentioned with Beta waves, Gamma waves often operate at the same frequency as the neurons in your muscles so we need to be careful about what information we are using!
Spotlight on Alpha Waves
Now you have know a little bit about the entire brain orchestra! It will be our mission to understand the how our brainwaves function and how we can use these to interact with our current technology in an effective, societally conscious manner. If you thought these different brainwaves are cool, just wait until we have the chance to learn even more together!
There is a lot we can learn from this new information and so many places to start! For today let’s spend a little bit of time understaning our Alpha waves a bit more. As we mentioned above, Alpha waves are one of the most commonly used parts of our brain orchestra. When our Alpha waves are playing very “loud”, we can reasonably say that we are relaxed, calm and handling whatever task we are set on doing without too much anxiety.
But wait! Something this amazing couldn’t be this easy, right!? Sadly yes, you are correct. Alpha waves are also affected by something called “Alpha Blocking”. Believe it or not, the special neurons in your brain called “pyramidal neurons” are activated when your eyes are closed, making our Alpha waves more powerful. On the opposite side, when your eyes are open, these neurons stop activating and your Alpha wave amplitude will decrease. This interference is another example of an artifact, which you can learn about on our page discussing raw EEG signals and artifacts here.
For now, this is an interesting way we can interact with our NeuroMaker Connect software. Take a look at your Alpha waves when you eyes are open, close your eyes for 5 seconds and then look at them again. You will notice that your Alpha waves will start low and then increase when you open your eyes! For a more dramatic example of this effective, try blinking your eyes as fast as you can while looking at your Alpha wave readings. You will notice that your waves will go up and down very fast leading to very dramatic changes in your Alpha graph. Give it a try!
As you can imagine, this kind of interference is something that we need to remove in order to focus on the signals coming from our brain. After all, we are studying brain computer interface, not eyelid detection! To make your lives easier, we have removed some of this interference for you in the attention algorithm which you can read about in our description of attention here.