Mind Over Machine

Rudolph expects other approaches to pay off down the road. "Out at 20 years I have a lot of hope," he says. He points to a new kind of brain imaging known as magnetoencephalography, or MEG, that uses magnets to pick up electrical activity in the brain. MEG has the sort of speed and resolution that might make a brain-machine interface possible. In their current form, MEG scanners have to be protected by shielded walls and cooled with giant tanks of helium.
But Rudolph speculates that room-
temperature superconductors and other materials of the future will make MEG portable. "If you think about using superconducting magnets, maybe you could figure out how to make a helmet," he says. It might be possible in a few decades to design a helmet-like scanner that a soldier could wear along with a signal-processing supercomputer in his backpack. "At least DARPA’s got some people looking at that," Rudolph says.




One of the ways you can tell that the monkey-controlled robot arms at Duke aren’t science fiction is that sometimes they don’t work. Some days the circuit boards fry, and other days the prospect of a reward of juice just isn’t enough to motivate monkeys to play the game. For all the progress the researchers have made in recent years, the work is still hard, and there’s a lot more hard work ahead before they see their research making a difference in people’s lives.


Take the equipment itself. Wires sprout from the implants in a monkey’s head and are jacked into a big signal processor, which in turn is plugged into a computer, which in turn is
connected by cables to a robot arm. The Duke researchers will need to design a far more portable, unobtrusive system to make it practical for humans. They envision implanting an array of electrodes in key regions of a quadriplegic patient’s brain. The signals detected by the electrodes would travel through a wire to a small processor embedded in the skull. From there, the processor would wirelessly transmit its signals out
of the body. "It’s like having an implanted cellphone," says Nicolelis.


These signals would be picked
up by a portable computer, which would then generate commands for the artificial limb. Patrick Wolf has been aggressively tackling this part of the system, and has already built a wireless backpack computer for the Duke monkeys, with enough power to transmit their brain signals 100 meters through the air.


The researchers are also grappling with the fact that getting commands out of the brain is not the full secret to controlling an arm. The brain also needs feedback in order to make its commands more precise. Imagine trying to pick up a glass of water without a sense of touch: Instead of guiding your fingers around its side, you might simply knock it over. Or, once you’d managed to grab the glass, you might crush it accidentally as you tried to pick it up. Or, after passing those stages successfully, you might just splash your face with water.


John Chapin is working on ways to give people the feedback they’ll need to make the Duke brain-machine interface a reality. He’s experimenting with how to deliver information directly into the brain —particularly to the region of
the brain that handles the sense of touch. But that’s long-term research. In the short-term, a group at MIT is designing a cloth-like material that can be attached to a place on a person’s body where he or she still has a sense of touch. Force sensors on the limb can then relay their signals to the cloth, which will turn that information into different vibrations. It’s not the same thing as feeling a glass in your hand, but your brain can probably learn to take advantage of the information.


Learning, in fact, turns out to be the secret weapon of brain-machine interfaces. Nicolelis’s latest studies have shown what is happening to the Duke monkeys on a neurological level as they use the dots and circles on the computer screen to alter the commands their brains generate. "Now we have plenty of evidence that the brain is changing, and in ways I didn’t expect," says Nicolelis. "It happens in a matter of minutes." As the monkey trains, neurons in its brain begin to alter their firing patterns. More and more neurons get involved in producing commands—in fact, the number can triple. At the same time, a special set of neurons emerges that becomes active only when the monkey operates the robot directly with its brain, and not when it uses the joystick. Remarkably, these neurons switch on as soon as Nicolelis disables the joystick.