The findings are the first to suggest that the long-term use of brain-machine interfaces could lead to partial neurological recovery, even in patients with complete paralysis, the researchers said.
In the study, the patients who had been paralyzed for five to 13 years learned how to use brain-machine interfaces, which are systems that translate brain signals into commands, and move a device such as a prosthesis. The patients started out by learning to control an avatar in avirtual reality environment. Later, they moved on to more challenging equipment, including walking devices that used a harness to support patients' weight as they developed strength and the proper gait.
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Eventually, after months of training, the patients were able to use the mind-controlled robotic exoskeleton. This is the same exoskeleton that a paralyzed man used to kick the first ball of the 2014 World Cup in Brazil.
The patients also wore a sleeve that delivered feedback, in the form of vibrations to their forearm that were in sync with the rolling of the robotic feet on the ground. This was done to enhance their experience of walking, making their brains feel more like they were really walking by themselves, the researchers said.
The researchers said they think the brain-machine interface training, along with the sensory feedback helped the patients to re-engage the spinal cord nerves that survived their trauma. Previous studies have shown that patients with complete paralysis may still have some spinal nerves intact, Nicolelis said.
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"Over time, training with the brain-machine interface could have rekindled these nerves," Nicolelis said. "It may be a small number of fibers that remain, but this may be enough to convey signals from the motor cortical area of the brain to the spinal cord."
The researchers plan to continue their evaluation of the patients in the study and to start a new study of patients with more recent spinal cord injuries to see if this second group of patients can respond more quickly.
The study is published today (Aug. 11) in the journal Scientific Reports.
Original article on Live Science.