Is it possible to overcome paralysis by harnessing thoughts?
A man who was paralysed from the shoulders down after a bicycle accident in which he ploughed into the back of a mail truck is now able to move his arm for the first time in eight years, thanks to thought-control technology, also known as neuroprosthetics. “He can now think about moving his arm, and his arm moves,” said Robert Kirsch, a professor of biomedical engineering at Case Western Reserve University in Cleveland, Ohio, who was involved in the research.
Using sensors implanted in his brain and electrodes in his arm, the patient is now able to carry out a range of tasks, from drinking through a straw to eating pretzels, and even feeding himself mashed potato with a fork.
How does the technology work?
Put simply, the man – Bill Kochevar, now 56 – had two arrays of microelectrodes implanted in the region of his brain that is involved with movement, the motor cortex; specifically, in the area of the motor cortex that deals with the hands.
But decoding which thoughts – or more precisely, which signals in the brain – are linked to which movements is a tricky business. To help the computer system match them up, Kochevar spent four months in training, during which he used a virtual-reality setup to learn to control the movements of an on-screen arm with his thoughts.
The team implanted 36 electrodes into various parts of the muscles in his arm. After 18 weeks’ training, in which the electrodes in the arm were used to stimulate the muscles and to build their strength, the electrodes were connected to the computer system and to the implants in Kochevar’s brain, allowing him to make and control arm movements with his thoughts. A mobile arm support, which is also thought-controlled, helped to combat the effect of gravity on Kochevar’s arm.
“We have been able to take the electrical signals that represent his thoughts and use them to control stimulation of his arm and his hand,” said Bolu Ajiboye, lead author of the research, who is also from Case Western Reserve. “Now we can tell the world that it is possible to reconnect the brain and make the arm move again,” added Kochevar.
Are brain implants safe?
According to the study, Kochevar had the brain implant for almost two years before the end of the reported research, and had just four minor issues relating to the device. Nevertheless, this is invasive brain surgery, which always carries risks.
Does this mean we can cure paralysis?
No. This doesn’t heal damaged tissue, and hence does not repair the underlying spinal injury. Instead it bypasses the injury, providing an alternative route through which the brain can control movements of the body.
But is it a solution for paralysis?
Unfortunately, this is only one individual and a proof-of-principle study – the technology is not yet ready for use outside of the lab. What’s more, the movements were slow and restricted. While the technology allowed Kochevar to move his arm and grasp objects, it did not restore a sense of touch, meaning that he was not able to feel the object he was picking up or holding. But he was able to complete tasks even with his eyes closed.
How does this fit in with previous work?
Last year it was revealed that 24-year-old Ian Burkhart, who has less severe paralysis than Kochevar, had regained movements in his hand and fingers, allowing him to carry out a range of actions, from swiping a credit card to playing the video game Guitar Hero. The success was achieved using a system similar to that in the latest study, but the electrodes that stimulated Burkhart’s muscles were contained in an external sleeve.
Thought control has also been used to command robotic limbs: in 2015, gunshot survivor Erik Sorto demonstrated the ability to reach and grasp with a robotic arm controlled by a neuroprosthetic device.
The sense of touch is also being explored, with the hope that eventually paralysed individuals will not only be able to make movements, but also receive some form of haptic feedback on these movements. Last year it was revealed that a paralysed man, Nathan Copeland, could not only control a robotic arm using his thoughts, but could also “feel” when the robotic hand was touched.
What does the future hold?
Despite being in the early stages, this latest work is an exciting development that adds weight to the hope that, through technology, paralysed individuals will be able to carry out a wide range of previously impossible movements and actions, thus allowing them far greater independence. “It’s going to help a lot more people, for years to come,” said Kochevar.