For humans and animals, the ability to walk has its source in the brain. The brain sends electrical signals through the spinal cord to the legs, and this causes movement. If a brain signal is interrupted and does not reach the nerves in the leg, for example, then that limb is paralyzed. For the first time researchers have managed to bypass the damaged spinal cords of rhesus monkeys, allowing them to walk again.
In order to carry out the experiment, researchers severed parts of the spinal cords of two rhesus monkeys to paralyze one of their legs. The transection lead to an interruption of the brain signals to the muscles in one leg, so the rhesus monkeys couldn’t walk normally anymore. Researchers then implanted a microchip into the specific part of the brain responsible for the monkeys’ movements. The chips recorded every electric impulse produced by the monkeys’ neurons and sent these to a computer. The computer then calculated patterns of activity. Those patterns were transmitted to sixteen electrodes that had been previously implanted onto each monkey’s spinal cord below the injured section. By stimulating the right nerves, the electrodes made the leg muscles move again, enabling the monkeys to move their paralyzed legs almost normally. The information exchange between the microchip implanted in the brain and the electrodes took place via Bluetooth and infrared in real-time.
According to Erwan Bezard from the University of Bordeaux (France), both monkeys were able to move immediately after the operation without any training or rehabilitation. So far, the rhesus monkeys can accomplish easy movements like walking; however, balancing or navigating obstacles is currently not possible with this technology.
At this stage it is not clear if the technology can be used for humans as well. It will be necessary to do more research on fully paralyzed monkeys, where a larger portion of the spinal cord has been severed. This would provide a much more accurate representation of the type of paralysis usually found in humans. To date, chips have been implanted into human brains in other experiments and some positive results have been achieved. For example, one paralyzed man was able to move his hand using his thoughts. By wearing a pressure sleeve that responded to his brain activity on his forearm, he was able to stimulate, and therefore move, certain muscles. This gave him some control over his hand, which he previously did not have.
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