"And you'll see there are little white disks scattered around on your head," Dr. Wolpaw explained.
Those disks are electrodes that pick up the faint electrical activity that brain cells create when they communicate with each other. Vaughan put a conductive gel on top of Pelley's scalp to help the electrodes pick up the signals.
Pelley was thinking of the letters of a word that only he knew. Every time the computer flashed the correct letter on the screen, he silently thought to himself, 'That's it, that's the one.' That feeling of recognition set off a unique electrical pattern in his brain, which the computer picked up.
It worked the first time Pelley tried it, without a single mistake, spelling out "THOUGHT" with the help of BCI.
"You know, I can imagine some people watching this interview are thinking to themselves, 'Wait a minute, they're connecting the brain to a computer.' Are we moving in the direction of reading people's thoughts? Are we, is this mind control around the corner?" Pelley asks.
"No, No it is not - it is certainly not mind control and it's different from reading people's thoughts. And it's important to realize this requires the cooperation of the person," Wolpaw explains.
As remarkable as this is, some scientists believe this technology is limited, because putting electrodes on top of the scalp is like listening to a symphony from the street outside the concert hall. So what would happen if the electrodes were inside the brain?
That's what they're doing at the University of Pittsburgh, implanting electrodes inside the brains of monkeys. Andy Schwartz, a neuroscientist at the university, implanted a grid of electrodes. It's tiny, but there are 100 sensors, each listening to a different brain cell, or neuron.
It's like listening to the symphony of the brain, but now sitting in the front row. Schwartz has been decoding that language by watching the monkey's movement and recording the corresponding signals in its brain.
Asked what that tells him, Schwartz says, "So there's a relationship between how fast the neuron fires and the way the animal moves its hand. And we're trying to understand that relationship so that if we see a neuron firing we can say, 'Ah, the animal's about to make this kind of movement.'"
Once Schwartz started to figure out that relationship, he was able to connect the monkey's brain directly to a robotic arm. Within days, the monkey operated the arm as if it was his own. "The monkey has both arms restrained. And we're recording brain signals from its brain and it's using those brain signals to operate this entire arm," Schwartz explains. "As well as the gripper"
Schwartz says the monkey is operating the robotic arm with nothing but his thoughts. Asked what the chances are that a human would be able to do the same thing, he says, "Oh, we think a human being could do much better."
Cathy Hutchinson is well on her way to finding out: she's among the first humans to have her brain directly wired to a computer. Years ago, Cathy suffered a stroke that left her mentally sharp but trapped inside a paralyzed body and unable to speak, "locked in" like Scott Mackler.
Three years ago, Cathy volunteered to have the same kind of sensors Pelley saw in the monkeys implanted in her motor cortex, which controls movement and is located right on the surface of the brain. The sensors connect to the computer through a plug on her head. The system is called "Braingate" and it was created by a team led by Brown University neuroscientist John Donoghue.
"If you look at this square each one of these little black boxes is the electrical signal coming from one electrode in the brain," he explains.
Each one of the little black boxes is a neuron firing. "It's its electrical potential. It lets out a 1/1000th of a second pulse," Donoghue explains.
Asked how well we understand this language, Donoghue says, "We have a somewhat of an understanding. We know that there's a general pattern of, for example, left/right, up/down, even fast or slow."