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A team of scientists from the Swiss Federal Institute of Technology have developed an implant, which has proved successful in allowing monkeys with paralysis in one leg to regain control and movement of it. If the spinal cord becomes damaged or severed, neurological signals that control limbs can no longer reach the targeted tissue and this causes paralysis. By creating an innovative technology that acts as an alternate route for the signals from the brain to reach the limb, the scientists allowed the monkeys to walk correctly again.

The technology is made up of four separate components: two implants, a computer and a pulse generator. The first implant is placed in the brain on the region of the motor cortex that controls the leg. Neurons in the brain work by sending electric signals to each other, and then down to the spinal cord. It is possible for the implant to pick up on these electrical peaks and record them as data. The implant records electronic signals from around 50-100 neurons, which allows it to pick up on basic movement commands, such as thinking about moving the leg, and basic movements such as up and down.

The recorded data is sent to a computer, which decodes it from the electrical signals and then relays the information to a pulse generator, which sends the pulse to a second implant in the monkey’s lower spine. This second implant then imitates the signal that would have been sent to the leg if the spinal cord was not severed and the monkey was not paralysed. As a whole, it  has allowed monkeys to regain control of their leg movements. The device simply acts as a bridge over the severed cord. The sooner the technology was implanted after the monkey was partially paralysed, the quicker it could regain control of its paralysed leg. The monkeys were able to walk almost normally a mere three months after the implant; the foot was not dragging and was fully weight bearing.

As a whole, it  has allowed monkeys to regain control of their leg movements

This is a breakthrough in neurotechnology, as it is the first time that technology has been able to restore movement in primates. Neurotechnology has become a focal point for overcoming paralysis, for example, using brainwaves to control a robotic limb. Before this technology it was hard for scientists to imagine paraplegic patients ever regaining control of their limbs. Now, scientists believe that this technology will have many future uses. It is still in its early stages and will most likely only go on human trials in the next five years, but small feasibility trails have started in humans.

These feasibility trials will test each component one by one in humans. The technology is most likely to appear first in rehabilitation units for patients who have spinal injuries, but only where the cord is not fully severed. This will help them to regain some control of their limbs by strengthening the remaining nerves, allowing the correct signal to be sent and encouraging natural repair systems. The device still has a lot of limitations. For instance, the signals only work one way, so no feeling is felt in the limb.

Another limitation is that it is not known how much weight the limb can bear. It is also unlikely to be able to allow completely paraplegic patients to walk again due to the fact that humans are bipedal. This will make balance and steering challenging, and frames may still have to be used. However these limitations will most likely be overcome, as technology in this area is rapidly improving. Despite these limitations the most exciting thing about this technology is that it shows what is possible and opens doors to many other neurotechnologies, which will benefit many paraplegic people in the future.

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