Harnessing brain signals to control keyboards, robots, or prosthetic devices is a hot area in medical research. Now, a rare peek at a human brain hooked up to a computer shows that the brain and the devices it controls can adapt to each other quickly, and possibly to the brain’s benefit.
Researchers at the University of Washington (UW), Seattle, tracked signals from surfaces of the brain of volunteers who were imagining movements in order to control a cursor while watching the cursor’s movements. The results, published February 16 by the Proceedings of the National Academy of Sciences, show that watching a cursor respond to one’s thoughts prompts brain signals to become stronger than those generated in day-to-day life.
“Bodybuilders get muscles that are larger than normal by lifting weights,” said lead author Kai Miller, a UW doctoral student in physics, neuroscience, and medicine. “We get brain activity that’s larger than normal by interacting with brain-computer interfaces. By using these interfaces, patients create super-active populations of brain cells.”
The finding holds promise for rehabilitating patients after stroke or other neurological damage. It also suggests that a human brain could quickly become adept at manipulating an external device such as a computer interface or a prosthetic limb.
The team of computer scientists, physicists, physiologists, and neurosurgeons studied eight patients awaiting epilepsy surgery at two Seattle hospitals. Patients had electrodes attached to the surface of their brains during the week leading up to the surgery and agreed to participate in research that would look at connecting brains to a computer.
Asking people to imagine performing a movement-such as moving their arm-is commonly done to produce a brain signal that can be used to control a device. But how that process works is poorly understood.
“A lot of the studies in this field are in non-human primates,” Miller said. “But how do you ask an animal to imagine doing something? We don’t even know that they can.”
The researchers first recorded brain patterns when human subjects clenched and unclenched a fist, stuck out a tongue, shrugged their shoulders, or said the word “move.” Next, the scientists recorded brain patterns when subjects imagined performing the same actions. These patterns were similar to the patterns for actual action but much weaker, as expected from previous studies. Finally, the researchers looked at signals when subjects imagined performing the action, and those brain signals were used to move a cursor toward a target on a computer screen. After less than ten minutes of practice, brain signals from imagined movement became significantly stronger than when actually performing the physical motion.
