A woman, aged 52 and tetraplegic, has managed to control and manage a newly developed robotic hand with her thoughts only, U.S. scientists revealed in the journal The Lancet. Experts explained this advancement required a new form of transmission of nerve impulses that uses the natural control of muscles as a reference.
Jan had lost the ability to move her arms and legs more than 10 years ago due to a degenerative disease called spinocerebellar degeneration, which caused damage to his spinal cord similar to a fracture of the spinal column in a traffic accident. The team from the University of Pittsburgh, Pennsylvania (USA), directed by Andrew Schwartz, treated the patient before she was completely quadriplegic, although shortly after putting on the electrodes she could not longer move her arms.
Scientists implanted her with two microelectrodes in the motor cortex of the brain. These were connected to a robotic arm with an artificial hand and fingers. Two days after the operation the woman could move the arm, from left to right, up and down, only through her thoughts. After 13 weeks of training, she could perform certain actions in order to take things and her movements became faster and more efficient, as scientists revealed.
The prosthetic arm, designed by the John Hopkins University's Applied Physics Laboratory. DARPA and JHU/APL.
The innovative technique which makes use of the robotic arm is more intuitive for patients, because instead of having to think about where to move the arm, the patient simply has to focus on the goal, as one would do when trying to to score a basket. Although several groups around the world are developing similar prototypes, none has achieved these impressive results. Jan managed to move objects on a table, including cones, blocks and small balls, catching them and changing their location.
"We were impressed by how quickly she was able to acquire his skill. It was totally unexpected," said Andrew Schwartz, professor of neurobiology at the University of Pittsburgh and lead investigator of this project. "At the end of one day, when she was doing these beautiful movements, she was very excited."
To connect the woman to the robotic arm, doctors performed a four-hour operation to implant two tiny electrodes grids of 4 mm on either side of Jan's brain. Each grid has 96 tiny electrodes that protrude 1.5 mm . The electrodes were pushed just below the surface of the brain, near the neurons controlling the hand and arm movement in the motor cortex. Before Jan could use the arm, the doctors had to record her brain activity as she imagined various arm movements. For this, she was asked to look at the robotic arm and try to move it in the same way as she would do with her own arm.
What is yet to come
There are several challenges yet to solve. One is that the robot hand can send sensory impulses to people, so that they can interact with objects according to their texture and temperature.
A second objective is to develop thinner electrodes with a thickness of about five thousandths of a millimeter, to avoid problems like the one Jan has developed after the publication of the study. It is about a scar tissue that forms around the electrodes and that degrades the signals the brain sends to the computer. With smaller electrodes, the body may not trigger any healing process.
Another major focus of future work is to develop a wireless system, so that the patient does not have to be physically connected to the computer that controls the robot arm.
