What is it like to participate in an EEG study?
What is EEG?
EEG, short for electroencephalogram, is a method of detecting and measuring electrical impulses in the brain. It is a very safe and non-invasive way to measure brain activity. Our equipment for uses a set of 128 sensors embedded in small sponges and connected to each other by fine elastic and strategically placed on a net.
These “nets” are certified to the highest safety standards and are used worldwide in research and clinical environments, including with children and even newborns. The electrodes detect minuscule electrical impulses caused by ion movement between nerve cells in the brain. Through them, we can examine and research cognitive processes and behavior.
What is involved in an EEG study?
After we finish this consent process, we will check your eyesight and handedness. You will then be seated in a special chamber that is protected from loud sounds and electrical noise. There, we will measure the size of your head to determine what size sensor net to use; we will also mark the center of your head with a soft, washable wax marker to help us place the sensors.
Then, we’ll measure how well each electrode is working. This involves us passing an extremely tiny electrical current through each electrode – well below what you’ll be able to feel – about the same strength as the electrical field generated by a fridge magnet. The computer, however, is able to pick up those tiny signals and give us a reading that shows which electrodes have good connections. We will work on the electrode positioning until each electrode has a good reading.
We want you to feel relaxed and comfortable. If you have a positive experience, it improves the quality of the data we record. If our participants get anxious or tired, the experiment will not work as well. So, please ask any questions at any time, and tell us what we can do to make you feel comfortable.
Why is the net wet?
Before being placed onto your head, the EEG nets will be soaked in a solution of electrolytes and baby shampoo. The electrolytes in the solution increase the conductivity between the sensors in the EEG net and the participant's scalp, and the baby shampoo in the solution helps break down the natural oils in the hair. This improves the net’s ability to pick up signals generated by the brain and allows for higher-quality EEG signals. At times during the experiment, it may also be necessary to re-wet some of the electrodes with pipettes, since they may become dry and less receptive.
Can I wear contacts?
No. This is because any movement during the recording, particularly facial movements, will cause artifacts in our data. This is why we advise our participants to avoid blinking excessively and not to chew gum while being recorded. Contact lenses could cause your eyes to dry out faster, so you'll blink more during the experiment, which is why we recommend you wear your regular glasses when coming in for this study session.
This is what an artifact looks like
Any risks I need to worry about?
With EEG recording, there is a small risk of skin irritation. Your skin may get red where the sensors come into contact with you, but this usually goes away in about 15 minutes. We minimize this risk by careful choice of electrolyte, which is a simple salt solution (potassium chloride), and by careful and complete disinfection of electrodes.
There is also a very small risk of an electric shock from the sensors, which we keep as low as possible by using very stringent safety procedures. We use highly rated circuit breakers and isolation transformers (special devices that separate the equipment from the main power source) to ensure that anyone using our equipment is safe. Because of our safety precautions, the risk of getting an electric shock is smaller than the risk involved in using a toaster or other small domestic appliances.
COVID Safety
Because of the placements of some electrodes, we will ask you to remove your mask while we putting on the net and while recording. For this part of the experiment, all researchers working with you will be changing into an N95 mask. We will maintain social distancing when possible, and we will keep the number of researchers working with you to a minimum.
All members of the research team have been fully vaccinated against COVID-19. We host no more than one participant in the lab in any 4-hour period. In between each participant, all surfaces are disinfected, and the air is purified with HEPA filters. The towels used during the EEG recording are laundered between each use. All the equipment that touches your child has been disinfected to hospital standards between each use.
If you have any more questions or concerns about participating in an EEG study, feel free to reach out to us at ncllab@tc.columbia.edu, or call us at 212-678-7403. We are happy to talk to you about the study in more detail!