Scientists have implanted electrodes in the brains of seven epileptic people in a bid to understand how humans learn new skills.
They wanted to see what happened when people learned to use a device called a brain-computer interface, which allows them to interact with computers simply by thinking. This revolutionary technology is in an embryonic state, but could one day allow paralysed people to operate robotic arms and legs to overcome their disability, or even allow stroke victims to speak again.
Researchers at the University of Washington implanted electrodes into the brains of severely epileptic people who were already in hospital for a procedure to identify which part of their brain was causing seizures.
Surgeons cut through the scalp, drilled into the skull and then installed a thin sheet of electrodes directly on top of the brain. They graciously allowed researchers to then have a go on the patients, who were asked to move a mouse cursor on screen by using their thoughts.
Their brainwaves were transmitted to a laptop, which was able to move the cursor within 40milliseconds of receiving the information.
Researchers found that when patients first started trying to move the cursor, brain activity was focused in the prefrontal cortex, an area which is associated with learning a new skill. But after 10 minutes, activity in this area decreased and the signals began looking more like those produced during automatic responses.
Jeffrey Ojemann, professor of neurological surgery, conducted the experiment at the University of Washington along with Jeremiah Wander, a doctoral student in bioengineering, and Rajesh Rao, a professor of computer science and engineering.
Ojemann said: “Now we have a brain marker that shows a patient has actually learned a task. Once the signal has turned off, you can assume the person has learned it.”
Previous experiments have successfully installed brain-computer interfaces in humans and monkeys, but this experiment was the first to clearly map the pattern of brainwaves as the device is used. One woman in Pittsburgh was even able to give high fives and feed herself chocolate using a mind-controlled robot arm.
“We now have a larger-scale view of what’s happening in the brain of a subject as he or she is learning a task,” Rao said. “The surprising result is that even though only a very localized population of cells is used in the brain-computer interface, the brain recruits many other areas that aren’t directly involved to get the job done.
“What we’re seeing is that practice makes perfect with these task. There’s a lot of engagement of the brain’s cognitive resources at the very beginning, but as you get better at the task, those resources aren’t needed anymore and the brain is freed up.”
In the future, less invasive procedures could allow humans to control machines by, for instance, wearing an electrode hat. However, implanting the device into the brain eliminates interference and allows scientists to record data at higher frequencies.
The researchers suggested that a wireless device could even be permanently built into a person's brain to allow them to control robotic limbs.
“This is one push as to how we can improve the devices and make them more useful to people,” Wander added. “If we have an understanding of how someone learns to use these devices, we can build them to respond accordingly.”
The research team, along with the National Science Foundation’s Engineering Research Center for Sensorimotor Neural Engineering headquartered at the University of Washington, will continue to develop these technologies. ®
The research is described in the paper "Distributed cortical adaptation during learning of a brain–computer interface task", published in Proceedings of the National Academy of Sciences of the United States of America. ®