Jan Scheuermann is not your average experimental subject. Diagnosed with spinocerebellar degeneration, she is only able to move her head and neck. The paralysis, which began creeping over her muscles in 1996, has been devastating in many ways. Yet two years ago she seized an opportunity to turn her personal liability into an extraordinary asset for neuroscience. In 2012 Scheuermann elected to undergo brain surgery to implant two arrays of electrodes on her motor cortex, a band of tissue on the surface of the brain.
She did so as a volunteer in a multi-year study at the University of Pittsburgh to develop a better brain-computer interface. When she visits the lab, researchers hook up her brain to a robotic arm and hand, which she practices moving using her thoughts alone. The goal is to eventually allow other paralyzed individuals to regain function by wiring up their brains directly to a computer or prosthetic limb.
The electrodes in her head record the firing patterns of about 150 of her neurons. Specific patterns of neuronal activity encode her desire to perform different movements, such as swinging the arm to the left or clasping the fingers around a cup. Two thick cables relay the data from her neurons to a computer, where software can identify Scheuermann’s intentions. The computer can then issue appropriate commands to move the robotic limb.
On a typical workday, Jan Scheuermann arrives at the university around 9:15 am. Using her chin, she maneuvers her electric wheelchair into a research lab headed by neuroscientist Andrew Schwartz and settles in for a day of work. Scientific American Mind spoke to Scheuermann to learn more about her experience as a self-proclaimed “guinea pig extraordinaire.”
[An edited transcript of the interview follows]
Can you describe a typical day in the lab?
After I arrive in the morning, my assistant twists off the top coverings of the two pads on my head and wipes whatever’s sticking out of them with alcohol. She then connects me to two big cables and twists those down until a signal starts coming through.
Next we train with the computer and the robotic arm for about 20 minutes to half an hour before starting with the tests of the day. Usually it’s something like, pick up an object from one side of the table and move it to the other side as quickly as I can. We might take a quick break for lunch, and then I leave around 1:30. It’s usually about a four-hour day.
What was it like to use the robotic arm for the first time?
When I first started, I learned to move it left and right, and up and down, and after that I learned to open and close the fingers. Then I turned the wrist. With every new ability they gave me, I was reminded of what most babies do at some point. When my kids were three or four months old, they learned finally that they could control the things at the ends of their arms. I remember seeing them slowly turning their wrist this way and that, grasping and ungrasping their fingers. And eventually it became automatic for them, too. That image kept popping into my mind. I felt like a baby learning to use my hands.
How do you approach a new task?
At first we train with the computer. The computer does it while I watch and pretend I’m doing it. Then the computer learns how to interpret my brain signals and what I want to do, and then I start doing it. As I practice I get better and better.
Sometimes I adapt to the task very quickly and it’s all so natural. Other things require more concentration to learn. After they’re learned you do them over and over until they’re automatic.
What strategies do you use as you learn?
It’s interesting, there are two ways to do a task. One is to think about each move I’m making. So if I’m picking up a cube, I could think “move left, move forward, turn fingers left, clench fingers around object.” The other is you just look and go for it. That works much better than when I try to figure it out step by step.
There was one trial several months ago where I had to move the robotic arm back and forth over two lines as many times as I could in 60 seconds. I tried as best I could and I got 24. Then I had to do the same think while distracted, for instance while carrying on a conversation. And I got 24—the same thing! Then the distraction was counting backward by threes from some random number, and that was the same, 24, which is really fascinating. Sometimes not trying too hard is best. Let the hand do the task without thinking too much.
Have these experiments changed the way you think about your own brain?
I guess I’m just reassured to know that once our brain learns how to do things it doesn’t forget them just because we can’t do them anymore. If I magically got my limbs back, through stem cells or something, my brain won’t have forgotten how to walk. Or how to reach out and grab something or how to hug someone. The muscles might not be strong, but they’ll know how to do things.
I also have come to appreciate my brain even more. I’ve seen people who have arms that work and legs that work, but their brains don’t. They’re mentally handicapped. I’d so much rather have my brain than my legs. You know that quote, ‘you are more than the body you live in’? That’s so true for me.