“Think of it as a weird massage…”
Journal articles can often feel impersonal to the readers. The participants are nameless subjects, the equipment and the meticulous lab set-up overshadowed by the findings.
But as I learned firsthand, such studies are anything but impersonal.
I recently participated in an electroencephalogram (EEG) study in the lab of Per Sederberg at Ohio State University. The memory researchers were seeking volunteers from the science writing community. A group of 400 of us writers were going to be in town and they wanted to learn more about how our brains process memory of scientific information.
As the day approached, I realized I didn’t know the first thing about what would be involved with getting an EEG recording. I had written about the data coming out of these studies many times, but here are 5 things I learned by being a participant:
Salt is an excellent conductor, and the goal is to shepherd the electrical signals from the brain through the scalp and into the electrodes of the EEG cap.
It took about 20 minutes for Sederberg along with two research assistants (thanks Chad Gossett and Ana Khazan) to apply this gel all over my scalp using tiny blunt needles injected into 97 probes covering the EEG cap. It didn’t hurt but it did feel like a cross between a “weird massage,” as Gossett called it, and a childlike hair-tugging exercise.
The process was surprisingly involved – but in my case, successful. Pillars of gel covered my scalp so the probes could capture the electrical signals from my brain. Sometimes, it is more difficult to conduct the signal, and that can depend on a person’s hair and scalp. For example, people with long, thick hair tend to have more conductive scalps, Gossett said, as do people who keep their hair very short or have no hair at all (apparently, their scalps get thicker).
Even stranger than the gel application was the challenge of washing it out of my hair afterward in the lab. They kindly provided shampoo, a towel, comb and hair dryer – not items I expected to see in a neuroscience lab.
2. Your head will light up like a Christmas tree: As the gel is applied over the scalp, the 97 LED lights covering the white cap will change color – hopefully from red to yellow to green. They show the scientists when the electrical impedances are low enough.
It’s a relatively new way for scientists to ensure that they are detecting the full electrical signals from the brain without constantly checking a computer monitor. And it looks really cool – think Christmas tree crossed with Medusa (all the wires coming out the back)!
Once the probes were working, the researchers were able to collect 1000 samples a second across 95 channels. Of the 97 probes, one was the ground and one was for reference. The end result was more than 1 GB of data per subject.
3. No selfies during the study: Cellphones and other electronic devices cannot be in the room with the participant during the study. That’s because one of the biggest challenges of conducting EEG experiments is cutting out all the noise from our electric environment.
The room where I was sitting during the study was a Faraday cage, designed to block electric currents using fine metal mesh or perforated sheet metal in the walls and ceilings.
Luckily, the researchers were kind enough to let me take some photos right before the study got started.
4. It takes 8 minutes to clear your head and get a baseline: The study involved watching a few videos and then answering 87 difficult questions, but the hardest part for me was staring at a tiny cross for 8 minutes at the start. Although not all EEG studies measure resting-state activity, this particular study wanted to track fluctuations in neural activity without any external stimulation.
The instructions said I could think about anything or nothing, while remaining fairly still, but that I should look at the cross on the screen. In a small soundproof room, wondering what was coming next and when it would end, the 8 minutes felt like an eternity.
So I learned that “resting state” tasks are anything but resting, unless, of course, I had been allowed to close my eyes and go to sleep.
5. No lefties allowed: While getting my scalp gelled, I asked the research assistants if they had had it done to them before. Khazan explained that she couldn’t because she is left-handed. Then I remembered that the one qualifier for participating was that you be a right-handed. Why?
Neuroimaging, especially when studying memory or language, is a rightie-biased field, it turns out. Lefties and righties tend to exhibit language processing in different brain hemispheres – lefties sometimes on the right and righties almost always on the left. It is a generalization, Sederberg says, but because of these general differences, it would be challenging to aggregate brain data that comes from both lefties and righties.
So scientists have to separate them out to control for those differences. Because lefties are just 10% of the population, researchers have a larger recruiting pool with right-handed individuals. As a result, virtually all neuroimaging studies of language or memory processing – whether fMRI or EEG – to date have involved only right-handed individuals.
Starting leftie-only studies could prove daunting, as so much neuroimaging to date is with righties; it would require starting from scratch – but it’s something some researchers have called for in recent years.
I will never think about EEG studies, or any neuroimaging study for that matter, the same way again. But now that the study is over, I am eager to delve into the data. How did I and other science writers remember scientific information compared to a science novice?
Stay tuned. A post about those results will be forthcoming.
-Lisa M.P. Munoz