Medical researchers have successfully enabled a paralyzed monkey to move its hand, by delivering messages from the brain directly to the muscles, completely bypassing the spinal cord. This is a breakthrough for spinal-cord injuries, it opens doors to future brain implants that could restore movement in paralysed limbs.
A new Northwestern Medicine brain-machine technology delivers messages from the brain directly to the muscles – bypassing the spinal cord – to enable voluntary and complex movement of a paralyzed hand. The device could eventually be tested on, and perhaps aid, paralyzed patients.
The research was done in monkeys, whose electrical brain and muscle signals were recorded by implanted electrodes when they grasped a ball, lifted it and released it into a small tube. Those recordings allowed the researchers to develop an algorithm or “decoder” that enabled them to process the brain signals and predict the patterns of muscle activity when the monkeys wanted to move the ball.
The team says the monkey was capable of complex voluntary movements, and that the technique could eventually be used to help paralyzed people move again.
“We are eavesdropping on the natural electrical signals from the brain that tell the arm and hand how to move, and sending those signals directly to the muscles,” says professor said Lee E. Miller, PhD, Edgar C. Stuntz Distinguished Professor in Neuroscience and the lead investigator of the study, which was published in Nature.
“This connection from brain to muscles might someday be used to help patients paralyzed due to spinal cord injury perform activities of daily living and achieve greater independence.”
The researchers then gave the monkeys a local anesthetic to block nerve activity at the elbow, causing temporary, painless paralysis of the hand. A tiny multi-electrode array was used to detect the activity of about 100 neurons in the brain and link it to a computer that deciphers the signals that generate hand movements.
The monkeys’ brain signals were then used to control tiny electric currents delivered in less than 40 milliseconds to their muscles, causing them to contract.
The monkeys were able to pick up the ball and complete the task nearly as well as they did before.
“The monkey won’t use his hand perfectly, but there is a process of motor learning that we think is very similar to the process you go through when you learn to use a new computer mouse or a different tennis racquet,” says Miller.
‘This connection from brain to muscles might someday be used to help patients paralysed due to spinal cord injury perform activities of daily living and achieve greater independence.’