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Brain-Machine-Interface Restores Sensation & Voluntary Movement in Paraplegic Volunteers
Posted by Gingernut on Aug 18, 2016
During the opening ceremony of the 2014 football World Cup in Brazil, Juliano Pinto stepped onto the field of the Corinthians Arena. The man was about to make history. Flanked by two opposing teams, Mr Pinto stepped up to take the opening kick-off of the tournament. His left foot struck out to meet the ball and he raised a fist in triumph as the ball rolled away.
He did all of this whilst paralysed from the waist down.
Mr Pinto was able to complete this daunting task thanks to the work of more than 150 researchers, led by Dr Miguel Nicolelis of Duke University. Dubbed the 'Walk Again Project', the team have developed an exoskeleton called Bra-Santos Dumont, in honour of Brazil and its aviation pioneer, Alberto Santos-Dumont. Worn by Mr Pinto during the World Cup Opening Ceremony, the suit gave him the ability to voluntarily control the movement of his legs.
The Bra-Santos Dumont suit
Since 2014, the Bra-Santos Dumont suit has been used as part of a year-long research project involving 8 paraplegic volunteers, which found that the correct training could return both sensation and voluntary movement to paralysed limbs (videos below).
The Walk Again Neurorehabilitation Protocol
Over 12 months, the volunteers were trained on the Walk Again Neurorehabilitation protocol, a three-stage programme which promoted the volunteer's ability to produce brain signals associated with movement in able-bodied individuals.
Participants were asked to control an avatar, seen though an Oculus Rift virtual reality headset, using only their minds. They were hooked up to an EEG machine which recorded electrical impulses given off by the brain, through detectors placed against the scalp. These signals were translated into instructions which controlled the avatar's movements. Although this sounds complex, all the participants needed to do was imagine moving. When the avatar moved, the volunteers received 'haptic feedback'; vibrations on their arm which indicated when certain movements had taken place.
"The tactile feedback is synchronized and the patient's brain creates a feeling that they are walking by themselves, not with the assistance of devices," Nicolelis said. "It induces an illusion that they are feeling and moving their legs. Our theory is that by doing this, we induced plasticity not only at the cortical level, but also at the spinal cord."
Initially there was very little, if any, activity in areas of the brain associated with lower limb movement. A few months into the project however, the motor cortex became much more active when the volunteers were completing this task.
"Basically, the training reinserted the representation of lower limbs into the patients' brains." – Dr Nicolelis
One the volunteers had become proficient with the virtual reality task, they were upgraded to a robotic gait orthosis. Whilst suspended in a harness on a treadmill, participants used the same brain machine interface as the virtual reality task to control the orthosis. This helped not only to strengthen the representation of lower limbs within the brain, but also improve balance, muscle strength, dexterity and posture. Again they received tactile feedback, but this time from pressure sensors on their own feet and legs.
The third and final stage of the intervention involved the use of the same mechanical exoskeleton used by Juliano Pinto at the world cup. Again, movements were controlled by thought and the participants received haptic feedback.
Diagram illustrating each training phase. Credit: Nicolelis Lab
Over the course of the 12 month project, a number of neurological assessments were carried out to assess whether the training was providing any benefit to the participants. The results, however, were far more impressive than anybody could have predicted.
Despite 7 of the 8 patients having a baseline diagnosis of complete spinal cord injury, each one of them has regained voluntary movement of their leg muscles as well as the ability to feel both touch and pain in their paralyzed limbs. Some were even able to produce multi-joint voluntary movements. Furthermore, bladder and bowel control, as well as cardiovascular function, have all significantly improved as a result of this training. The number of bowel movements made directly correlated with the hours of upright walking completed.
As the video below shows, the range of movement achieved was remarkable (credit: Nicolelis Lab):
One of the most striking results, however, may be that 4 of the 8 patients have had their complete paralysis (ASIA A) diagnosis downgraded to an incomplete paraplegia (ASIA C) diagnosis on the ASIA scale (Grade A is complete paralysis and Grade E is normal functioning).
These findings completely staggered the research team, who expected only to provide paraplegics with an artificial way of moving around.
"We never predicted that by having patients interacting with these devices over a long period we might induce significant neurological recovery, including sensory, motor, and visceral improvements, all body functions lost due to a devastating spinal cord injury, such as the case of our eight patients". – Dr Nicolelis
The researchers theorised that the results were thanks to the long-term nature of the research, which may have both simulated neuronal restructuring within the brain and activated dormant spinal cord nerves which survived the index injury; of course such a theory would need to be thoroughly examined in order to be proven correct.
As expected due to the unmitigated success of the Walk Again Neurorehabilitation protocol, all 8 participants have continued with their training; a report with data for the last two years (from December 2014 to May 2016) will be published shortly. Their first report has already been published and is available in Nature.
As a result of his work, Dr Nicolelis has been awarded the 2017 IEEE Daniel E. Noble Award for Emerging Technologies for his "seminal contributions to brain-machine interfaces."
To get a better look at the research, take a look at this video from Dr Nicolelis' lab:
brain-machine-interfacedr miguel nicolelisexoskeletonfootball world cupjuliano pintoneuroscienceparalysisparaplegicresearchsciencescience of the futuretechnologythe future
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