Among the rolling hills of Durham, NC, Duke University’s Miguel Nicolelis is attempting to teach old monkeys new tricks. But first, their brains must learn to listen.Over the last few years, Nicolelis and his team have shown that brain signals picked up by electrodes implanted in animals’ brains can provide rudimentary control of robot arms. But there’s a hitch: the animals don’t know they are controlling anything. To get to the point where animals-and eventually humans-can take on more sophisticated tasks, Nicolelis says, real-time communication between mind and machine must become a two-way street.
So in Nicolelis’s lab a rhesus monkey is not only controlling a robot arm through brain signals picked up by electrodes implanted in its head, it is also getting feedback from the robot-for now, in the form of a cursor on a screen that shows the robot’s movements. Kept in separate rooms, the monkey and robot arm are linked via cables, a microcomputer, and a parallel processor. The next step will be to implement tactile feedback. When the monkey tries to use the robot arm to grab a rubber beer mug, the robot arm will send signals to force transducers placed on the animal’s upper arm; these motors will vibrate vigorously when the robot’s grip tightens. And eventually, Nicolelis says, the system could provide even more direct feedback by electrically stimulating sensory regions of the brain. “The trick is to give the right kind of feedback so the monkey’s brain will incorporate the robot as if it were a part of its own body,” he says.
Once they “close the loop” of brain-machine interaction, Nicolelis says, researchers can begin to think realistically about designing systems whose physical capabilities surpass those of normal people. One example: by bypassing nerves and muscles and connecting the brain directly to a robotic limb, he says, it may be possible to cut reaction times by a factor of six. He predicts that many labs will demonstrate such augmentation of basic physical abilities over the next five years.
As Nicolelis works to replicate and augment such everyday capabilities as grasping and lifting, researchers at the University of Michigan are pushing brain-machine interfaces into new realms of physical control. Biomedical engineer Daryl Kipke and his team are teaching rats and monkeys how to guide the movements of a fleet of mobile robots using only their minds. Feedback is important, Kipke says, because it allows the animals to gain experience interacting with a device that is completely foreign-in this case a half-meter-long, six-legged robotic critter named RHex (pronounced rex).
For now, the agile robot must be either programmed to run in a certain direction or remotely directed by a hand-controlled wireless link. But brain-machine interfaces, the Michigan researchers say, could allow for faster and better-coordinated control. In the distant future, soldiers or rescue personnel-possibly at multiple locations-might plug their minds into a central computer to control a fleet of RHexes in the field. Guided by brain impulses, the robots would carry out search-and-rescue missions in war zones and disaster areas, while sending audio, visual, and tactile feedback to their controllers. “That’s the home run,” says Kipke.
Although reaching that goal is probably still decades away, Kipke’s team is working toward it by extracting signals from neurons in the areas of the brain that are involved in planning and executing movements. With all the noise from surrounding cells, it’s like trying to listen to specific conversations in a baseball stadium. Within a year, the researchers will surgically implant arrays of silicon electrodes-each no wider than a hair-in an animal’s brain and connect each array to a flexible low-power circuit that looks like a one-square-centimeter Band-Aid on the animal’s skin. The circuit will speed up the overall processing of the signals and allow them to be sent wirelessly to a central computer. There, custom software will translate the signals into movements of a computer cursor, which the animal will watch. The next step, says Kipke, will be connecting the cursor to RHex’s wireless control system so that when the cursor moves left, the robot does the same.
By summer the Michigan team, together with physiologist Dan Moran at Washington University, plans to have a monkey in St. Louis navigate RHex through an obstacle course in Ann Arbor, MI. The control signals will pass back and forth via the Internet, and the monkey will monitor a graphical representation of the robot’s position and movements on a screen. The overarching goal of the current project is to test whether such interfaces can engage the brain-making use of both neural commands and feedback-to control increasingly remote and complex devices. “Within five years, we’ll know if we can do this,” Kipke says.