Paralyzed monkeys walk again thanks to brain implants

Scientists developed a brain implant which allowed paralyzed monkeys to walk. While doing the same thing with humans will be more complex, the research lays the foundations for future studies on bioelectronics treatments for paralyzed people.

Brain implants allow paralysed monkeys to walk (credit: A. Jackson/Nature)

Brain implants allow paralyzed monkeys to walk (credit: A. Jackson/Nature)

The study published last week in the journal Nature, was conducted by a team of researchers led by neuroscientist Gregoire Courtine.  Based at the Swiss Federal Institute of Technology in Lausanne (Switzerland) the researchers carried out most of the ground work in Beijing (China) where working with monkeys is less burdened by regulations than it is in Europe.

Interestingly, the results are not a sudden breakthrough but rather a progression from the research Courtine has been conducting for over a decade on rats and now applied to monkeys. The team mapped how electric stimuli from the brain – through the lower spine – control the leg muscles of healthy monkeys, while walking on a treadmill. They then recreated those signals in monkeys whose spinal cord was severed. Microelectrodes implanted in the brain of the paralysed animals were used to generate electric pulses in the lower spine and trigger the muscles in the monkeys’ leg to produce motion.

“The whole team was screaming in the room as we watched,” says Courtine. In fact, previous to this result many experiments had failed as the rhythm of the legs was imperfect, the feet were dragging and/or the movement was uncoordinated. But not this time: the monkeys moved their legs with enough coordination to actually support their own weight.

“Doing the same thing with humans will be more complex,” says Courtine. Decoding the human brain’s association between stimuli and movement is much harder. In this study for instance, the electrical activity had been recorded from the spinal cord before the injury, and ‘played it back’ to restore movement. “That’s an approach that wouldn’t be practical after an actual spinal-cord injury,” says bioengineer Chad Bouton, who researches devices to bypass spinal-cord injuries at the Feinstein Institute for Medical Research in Manhasset, New York (US). Also, walking requires coordination of the gait – which the monkeys in the current study did not demonstrate – as this is controlled by a different group of neurons.

Courtine has already started a clinical trial at the CHUV University Hospital of Lausanne, with the focus on rehabilitating paralyzed patients through the stimulation of coordinated walking. Two people have had the electric-pulse generators implanted in their lower spines – but not the microelectrode arrays implanted in their brains, which means they will not be able to control the movement themselves.

Here is the link to the video explaining the research.

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Carlo Bradac

Carlo Bradac

Dr Carlo Bradac is a Research Fellow at the University of Technology, Sydney (UTS). He studied physics and engineering at the Polytechnic of Milan (Italy) where he achieved his Bachelor of Science (2004) and Master of Science (2006) in Engineering for Physics and Mathematics. During his employment experience, he worked as Application Engineer and Process Automation & Control Engineer. In 2012 he completed his PhD in Physics at Macquarie University, Sydney (Australia). He worked as a Postdoctoral Research Fellow at Sydney University and Macquarie University, before moving to UTS upon receiving the Chancellor Postdoctoral Research and DECRA Fellowships.

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