Researchers at Brown University have developed a neural interface that allows users to control a robot arm using only their thoughts, technology they believe can assist paralyzed people in their everyday lives.
Research published in the May 16 issue of Nature describes how tiny devices implanted in the brains of two tetraplegic study participants allow them to steer the robot arm to do things like grasp a cup of coffee and guide it to their lips (see video below).
The study is part of the BrainGate2 clinical trial at the Brown Institute for Brain Science in Providence, R.I. It was led by institute director John Donoghue, who told Nature.com that his team's latest work is a major advance on an earlier accomplishment that involved using the neural implants to move a cursor on a computer screen.
"To move from this type of two-dimensional movement to movements involving reaching out for an object, grasping it and then guiding it in three-dimensional space is a huge step for us. It seems like more than one additional dimension in complexity," Donoghue told Nature.com.
Another researcher on the project, neuroengineer Leigh Hochberg, told the science site that seeing study participant "Cathy" successfully use the robot arm was an emotional moment for the team.
"We'll never forget that smile," he said.
Earlier this year, Swiss scientists at the Federal Polytechnic School in Lausanne demonstrated a robot "avatar" that can be manipulated by the thoughts of a person wearing a small, fitted cap with electrodes that measures brainwaves and transmits them through a computer.
That research is also focused on assisting people with full or partial paralysis, but the Swiss team's focus is on non-invasive technology.
The electrode cap worn by a partially paralyzed patient at a hospital in the Swiss town of Sion allowed the man to send a mental command to a computer in his hospital room, which then sent it to a second computer which passed the command on to a small robot at the team's lab about 37 miles away in Lausanne.
The Brown University team has an ambitious long-term goal which explains why it's pursuing implanted technology as opposed to a non-invasive mind-machine interface—it hopes to eventually dispense with external robot assistants and create a way for implant recipients to control their own limbs.
Cathy, who suffered the stroke that incapacitated her 15 years ago, had her device implanted in her motor cortex 2005 as part of the long-term study.
The two participants' implants are "tiny recording devices containing almost 100 hair-thin electrodes" that "record the neuronal signals associated with intention to move," according to Nature.com.
The latest trial utilized two different robot arms. One is a prosthetic prototype called the DEKA Arm System and the other is a heavier unit called DLR that is an external assistive device, the site reported.
In 30-second test periods, Cathy was able to grasp targets with the DEKA arm at a 45 percent success rate and at a 21 percent success rate with the DLR arm. "Bob," the other study participant had a 62 percent success rate with the DEKA arm, according to Nature.com, which didn't say how he did with the DLR arm.
Donoghue said the next step in the research would be to build wireless capability into the mind-machine interface so subjects wouldn't require leads to run from their heads to the robots they control.
