Partially paralyzed monkeys that received special brain implants have learned to walk again, thanks to the help of wireless electric signals, a new study revealed.
Led by a team of Swiss neuroscientists, the research demonstrates the first ever brain implant that can restore walking ability in primates, offering hope for a radical kind of therapy for humans.
Mapping Electric Signals
Study lead researcher Grégoire Courtine, a scientist from the Swiss Federal Institute of Technology, said the report is based on decades of research in rats. When it was applied to primates, the animals reacted the same way.
Courtine and his colleagues first mapped how electric signals are transmitted from the brain to leg muscles in healthy monkeys that walked along a treadmill. They analyzed the lower spine, where brain signals arrive before being transferred to leg muscles.
Afterward, Courtine and his colleagues recreated the electric signals among monkeys with severed spinal cords, focusing on several points in the lower part of the spine.
Paralyzed Monkeys Regain Movement
Researchers explained how it worked: a series of microelectrodes implanted in the brain of the injured monkeys received and decoded the signals that were associated with leg movement.
The electric signals were sent through a wireless device that generated electric pulses in the lower part of the spine. This process reanimated the legs of the monkeys into motion.
For instance, a rhesus macaque fitted with the brain implant recovered leg movements only six days after it was partially paralyzed in a surgical procedure that severed some of its nerves.
"The gait was not perfect, but it was almost like normal walking," said Courtine. "The foot was not dragging and it was fully weight bearing."
Another animal that received more severe damage to the nerves that controlled its right hind leg regained mobility two weeks after the brain implant was fitted, said Courtine. Both monkeys fully recovered in three months.
Potential Therapy For Patients With Spinal Injuries
Experts wonder whether the brain implant can be helpful in the rehabilitation of spinal injury patients whose spinal cords are not completely severed. Some nerve fibers are still intact in these patients' spinal cords, but it is not enough to move their limbs.
Courtine said doing the same research on humans will be much more complex because the brain decoding process will be more complicated.
But theoretically, if the implant reestablishes a link between the brain and the spinal cord, it could help the remaining nerve fibers to strengthen connections. This could ultimately lead to recovery of locomotive functions.
Meanwhile, Courtine is traveling to China and back to Switzerland for clinical trials, which are being conducted at the CHUV University Hospital of Lausanne. The findings of the study are published in the journal Nature.