Research conducted at the University of Washington in Seattle suggests that clinical applications that can assist people paralyzed by spinal cord injuries or neurological diseases are perhaps five years away from realization.
In a study published by Nature, scientists Eberhard E. Fetz, Chet T. Moritz and Steve I. Perlmutter demonstrated for the first time that a direct artificial connection from the brain to muscles could restore voluntary movement in monkeys whose arms were temporarily anesthetized.
The study was funded by the National Institutes of Health.
The researchers connected electronic implants to single nerve cells in the motor cortex — the area of the brain that controls voluntary movements — enabling the animals to move their paralyzed muscles. The electrodes implanted in the motor cortex were connected via external circuitry to a computer.
Target Practice
As part of the experiment, scientists taught the monkeys to play a target practice game using only their brain activity to move a cursor on the computer screen. After using a local anesthetic to block nerve conduction, effectively paralyzing the animals’ wrist muscles, the researchers then rerouted the neuronal signals to the paralyzed limbs — and the monkeys quickly learned to move them.
What Eb [Fetz] showed us is that monkeys can reprogram their individual neurons, Joseph Pancrazio, Ph.D., a program director at the National Institute of Neurological Disorders and Stroke, told TechNewsWorld.
“This level of adaptation raises hopes that clinical devices can be developed for paralyzed individuals to be used in any cell to control their muscles,” he said.
In other words, doctors wouldn’t have to implant the electrode in a specific location in the brain — that is, the particular neurons associated with movement of specific body parts. This study shows that any motor cortex cell — whether or not it was previously associated with movement in a wrist or leg or arm — can stimulate muscle activity.
“The brain is sufficiently plastic and can adapt to use signal generators to do job it needs to do, which is drive muscles,” Pancrazio said.
Building on FES
This study builds on established research called “functional electrical stimulation,” or “FES,” in which a paralyzed limb is artificially stimulated with implanted electrodes. Some 300 patients have had such devices implanted, Pancrazio said. “These systems are operated with external switches and allow the patient to control, say, his grasp — or the strength of his grasp.”
The University of Washington research took this development a step further by combining a brain-computer interface with real-time control of FES. Now, essentially all of the medical pieces are in place to provide mobility to the paralyzed, according to Pancrazio.
The tech piece needs to come next, he said, along with additional funding. “The materials used now are very stiff — they are typically made of microwires, metals or silicon — and cannot survive in the brain for a long period of time.” A more robust interface with the brain and additional improvements to FES will also be needed.
“But the proof of concept is there — it is something that can be realized and implemented,” said Pancrazio.
No Implants Required?
In fact, scientists are already pursuing other avenues of research that may well provide a better route to clinical applications.
“It is certainly an interesting study and constitutes an advance,” said Jonathan Wolpaw, chief of the Laboratory of Nervous System Disorders at theWadsworth Center in the New York State Department of Health.
“At the same time, in terms of clinical applications, it is not clear whether it is necessary to put implant electrodes into the brain to get movement control,” Wolpaw told TechNewsWorld. “There is strong evidence that by using brainwaves recorded from the scalp, it should be possible to get similar movement control.
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