Being able to control objects by simply thinking about them has long been the realm of science fiction, but a few smart monkeys are inching it toward reality. For the first time, neurobiologists have successfully demonstrated two-way interaction between a primate brain and a machine interface.
“We liberated the brain from the physical constraints of the body and allowed it to gain an extra virtual arm that can be used to explore a virtual world,” said Miguel Nicolelis, a medical doctor, Duke University neurobiology professor, and director of the Duke Center for Neuroengineering.
Their work, which was published in the current issue of Nature, could lead to a brain-controlled robotic exoskeleton that could give a paralyzed person mobility.
For this study, devices containing hundreds of hair-like filaments were implanted in different regions of the monkeys’ brains. These implants both record brain activity and deliver neural stimulation simultaneously and in real time, an accomplishment that until now had not been done.
The experiments involved two trained monkeys that already knew how to move a cursor across a computer screen with a joystick. The researchers showed the monkeys several objects that looked identical on the screen, but were encoded with a special pattern that the monkeys couldn't see and could only sense through the brain implants.
The goal for the monkeys was to touch the one object that they sensed was different by moving a virtual arm across a computer screen using only their minds. When they virtually touched the correct object, they were rewarded with juice. After several initial attempts, the monkeys started consistently picking the correct object, behavior that was proven not to be random.
While the experiment was going on, the neuroengineers used the implants to record the monkeys' sensing and decision-making in real time. The ability to record and sense brain activity in real time is a necessary step in the development of brain-controlled prosthetics. In order to work effectively, these devices must mimic the natural feedback and response between the brain and the limbs that occurs in people who aren't paralyzed.
“This is a major step forward into the translation of this whole field into clinical applications,” Nicolelis said.
After completing the Nature paper, Nicolelis says his team finalized a wireless interface that picks up signals from a tiny brain implant without the need to attach cables. The implants are comparable to pacemakers in the sense that they are worth the simple neurosurgical procedure to put them in, especially for completely paralyzed patients who can’t move at all, Nicolelis added.
Next, the neuroengineers plan to work on a prototype for a brain-controlled robotic exoskeleton with the international nonprofit the Walk Again Project, as well as specialists from neuroscience institutions in Brazil, Germany, and Switzerland. They want to debut a functional exoskeleton at the 2014 World Cup in Nicolelis’s native Brazil, giving an as-yet unknown paralysis patient the chance to walk onto the field.
“That would be a demonstration that this technology is becoming ready and can be very helpful to restore ability to patients,” Nicolelis said.
Philip Troyk is an associate professor of biomedical engineering at the Illinois Institute of Technology who researches neuroprosthesis and leads a Chicago-based company called Sigenics that makes the integrated circuits for implantable brain devices.
While we do know that the monkeys make choices based on sensing patterns, we still don’t know what their actual perception was, he said. In addition, neuroengineers will need to develop a permanent hardware system that could be implanted.
These challenges don’t diminish the importance of the study, though, Troyk said. “It allows us all to realize that if we can overcome some of the major technical problems of a chronic implant, then we may in fact be able to permanently have this communication with the brain.”
Todd Coleman is an associate bioengineering professor at the University of California, San Diego, who works on brain-machine interfaces. Coleman wonders what kind of implications the study will have in the distant future for people with neurological disorders such as autism.
“These findings need not be limited to thinking about someone who has some type of motor deficit,” he said.
At the University of Chicago, Nicholas Hatsopoulos is an associate professor of organismal biology and anatomy with a focus on researching neural prosthetic systems. Robotic exoskeletons bring Iron Man’s powerful suit to mind.
“In the movie he gets into this suit, and he’s using arms and hands to control this thing,” he says. “But imagine controlling it with your brain.”
Hatsopoulos sees research into brain-machine interfaces heating up at the moment. “This paper is an important contribution to that whole endeavor,” he said of the Duke study. “What we still need to do is to really develop a system that we feel confident provides genuine sensory perception.”