A MONKEY controls the hand of its unconscious cage-mate using thought alone. That may sound like animal voodoo, but it’s a step towards returning movement to people with spinal cord injuries.
The hope is that one day people who are paralysed could have electrodes implanted in their brains that pick up their intended movements. These electrical signals could then be sent to their paralysed muscles. Ziv Williams at Harvard Medical School in Boston wanted to see if sending these signals to nerves in the spinal cord would also work, as this might ultimately give a greater range of movement from each electrode.
His team placed electrodes in a monkey’s brain, connecting them via a computer to wires going into the spinal cord of an anaesthetised monkey. The paralysed monkey’s hand was strapped to a joystick, controlling a cursor that the other monkey could see on a screen.
Williams’s team recorded the conscious monkey’s brain activity and worked out which signals corresponded to the back and forth motion of the joystick. Through trial and error, they deduced which nerves to stimulate in the spinal cord to produce those movements in the anaesthetised monkey’s hand. When both parts were fed to the computer, the conscious monkey was able to move the other’s hand to make the cursor hit a target (Nature Communications, DOI: 10.1038/ncomms4237).
“It’s the first demonstration of brain-to-spinal-cord information transmission between two animals,” says Rajesh Rao at the University of Washington, Seattle.
This article appeared in print under the headline “Monkey voodoo holds key to movement in paralysed people”