Scientists Use Neuroprosthesis to Move Paralyzed Hand
Scientists at Northwestern University have created brain-machine technology that will deliver brain signals directly to muscles, bypassing the spinal chord. This technology may one day help paralysis victims regain muscle control.
The research was done on monkeys by measuring brain signals as they used their hand to perform simple tasks like grasping and dropping a ball. They used the information to create an algorithm that maps brains patterns and predicts muscle activity when the monkey used the ball.
Next a local anesthetic was administered to the monkey, temporarily paralyzing its arm below the elbow. Devices located in the brain and arm, together called a neuroprosthesis, allowed the monkey to pick up and drop the ball almost as well as 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. Things are different and you learn to adjust to them,” said Miller, a professor at Northwestern, in the scientific publication in Nature.
The apparatis detects a variety of movement, theoretically making it possible for the monkey to perform many other hand movements.
Previous prosthetics could only help a person with hand paralysis provided they still had control of their shoulder muscles. An upwards shoulder shrug would cause electrodes in the hand to close, while a downwards shrug allowed the hand to open.
This new system uses an implant called a multi-electrode array to detect about 100 electrodes in the brain responsible for muscle control. These signals are translated in a computer and used to move the hand via electrodes.
Although there are millions of neurons responsible for a single hand movement, the neurons monitored via the multi-electrode array are output neurons that send brain calculations to the muscles. The millions of other neurons make these calculations and only a few send them out to actually control the hand, those are the neurons scientists at Northwestern are concerned with.
The implications of this research are widespread. It could potentially be used to give back movement to people suffering from any number paralytic of injuries. The analysis of output brainwaves could one day be used to create a cybernetic prosthesis, giving someone who has lost a limb a fully functioning prosthesis.
“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,” said Lee E. Miller, Neuroscience professor at Northwestern University and the lead investigator of the study. “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.”