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  • I am a neuroscientist

  • with a mixed background in physics and medicine.

  • My lab at the Swiss Federal Institute of Technology

  • focuses on spinal cord injury,

  • which affects more than 50,000 people

  • around the world every year,

  • with dramatic consequences for affected individuals,

  • whose life literally shatters

  • in a matter of a handful of seconds.

  • And for me, the Man of Steel,

  • Christopher Reeve,

  • has best raised the awareness

  • on the distress of spinal cord injured people.

  • And this is how I started my own personal journey

  • in this field of research,

  • working with the Christopher and Dana Reeve Foundation.

  • I still remember this decisive moment.

  • It was just at the end of a regular day of work

  • with the foundation.

  • Chris addressed us, the scientists and experts,

  • "You have to be more pragmatic.

  • When leaving your laboratory tomorrow,

  • I want you to stop by the rehabilitation center

  • to watch injured people

  • fighting to take a step,

  • struggling to maintain their trunk.

  • And when you go home,

  • think of what you are going to change in your research

  • on the following day to make their lives better."

  • These words, they stuck with me.

  • This was more than 10 years ago,

  • but ever since, my laboratory has followed

  • the pragmatic approach to recovery

  • after spinal cord injury.

  • And my first step in this direction

  • was to develop a new model of spinal cord injury

  • that would more closely mimic some of the key features of human injury

  • while offering well-controlled experimental conditions.

  • And for this purpose, we placed two hemisections

  • on opposite sides of the body.

  • They completely interrupt the communication

  • between the brain and the spinal cord,

  • thus leading to complete and permanent paralysis

  • of the leg.

  • But, as observed, after most injuries in humans,

  • there is this intervening gap of intact neural tissue

  • through which recovery can occur.

  • But how to make it happen?

  • Well, the classical approach

  • consists of applying intervention

  • that would promote the growth of the severed fiber

  • to the original target.

  • And while this certainly remained the key for a cure,

  • this seemed extraordinarily complicated to me.

  • To reach clinical fruition rapidly,

  • it was obvious:

  • I had to think about the problem differently.

  • It turned out that more than 100 years of research

  • on spinal cord physiology,

  • starting with the Nobel Prize Sherrington,

  • had shown that

  • the spinal cord, below most injuries,

  • contained all the necessary and sufficient neural networks

  • to coordinate locomotion,

  • but because input from the brain is interrupted,

  • they are in a nonfunctional state, like kind of dormant.

  • My idea: We awaken this network.

  • And at the time, I was a post-doctoral fellow in Los Angeles,

  • after completing my Ph.D. in France,

  • where independent thinking

  • is not necessarily promoted.

  • (Laughter)

  • I was afraid to talk to my new boss,

  • but decided to muster up my courage.

  • I knocked at the door of my wonderful advisor,

  • Reggie Edgerton, to share my new idea.

  • He listened to me carefully,

  • and responded with a grin.

  • "Why don't you try?"

  • And I promise to you,

  • this was such an important moment in my career,

  • when I realized that the great leader

  • believed in young people and new ideas.

  • And this was the idea:

  • I'm going to use a simplistic metaphor

  • to explain to you this complicated concept.

  • Imagine that the locomotor system is a car.

  • The engine is the spinal cord.

  • The transmission is interrupted. The engine is turned off.

  • How could we re-engage the engine?

  • First, we have to provide the fuel;

  • second, press the accelerator pedal;

  • third, steer the car.

  • It turned out that there are known neural pathways

  • coming from the brain that play this very function

  • during locomotion.

  • My idea: Replace this missing input

  • to provide the spinal cord

  • with the kind of intervention

  • that the brain would deliver naturally in order to walk.

  • For this, I leveraged 20 years of past research in neuroscience,

  • first to replace the missing fuel

  • with pharmacological agents

  • that prepare the neurons in the spinal cord to fire,

  • and second, to mimic the accelerator pedal

  • with electrical stimulation.

  • So here imagine an electrode

  • implanted on the back of the spinal cord

  • to deliver painless stimulation.

  • It took many years, but eventually we developed

  • an electrochemical neuroprosthesis

  • that transformed the neural network

  • in the spinal cord from dormant to a highly functional state.

  • Immediately, the paralyzed rat can stand.

  • As soon as the treadmill belt starts moving,

  • the animal shows coordinated movement of the leg,

  • but without the brain.

  • Here what I call "the spinal brain"

  • cognitively processes sensory information

  • arising from the moving leg

  • and makes decisions as to how to activate the muscle

  • in order to stand, to walk, to run,

  • and even here, while sprinting,

  • instantly stand

  • if the treadmill stops moving.

  • This was amazing.

  • I was completely fascinated by this locomotion

  • without the brain,

  • but at the same time so frustrated.

  • This locomotion was completely involuntary.

  • The animal had virtually no control over the legs.

  • Clearly, the steering system was missing.

  • And it then became obvious from me

  • that we had to move away

  • from the classical rehabilitation paradigm,

  • stepping on a treadmill,

  • and develop conditions that would encourage

  • the brain to begin voluntary control over the leg.

  • With this in mind, we developed a completely new

  • robotic system to support the rat

  • in any direction of space.

  • Imagine, this is really cool.

  • So imagine the little 200-gram rat

  • attached at the extremity of this 200-kilo robot,

  • but the rat does not feel the robot.

  • The robot is transparent,

  • just like you would hold a young child

  • during the first insecure steps.

  • Let me summarize: The rat received

  • a paralyzing lesion of the spinal cord.

  • The electrochemical neuroprosthesis enabled

  • a highly functional state of the spinal locomotor networks.

  • The robot provided the safe environment

  • to allow the rat to attempt anything

  • to engage the paralyzed legs.

  • And for motivation, we used what I think

  • is the most powerful pharmacology of Switzerland:

  • fine Swiss chocolate.

  • (Laughter)

  • Actually, the first results were very, very,

  • very disappointing.

  • Here is my best physical therapist

  • completely failing to encourage the rat

  • to take a single step,

  • whereas the same rat, five minutes earlier,

  • walked beautifully on the treadmill.

  • We were so frustrated.

  • But you know, one of the most essential qualities

  • of a scientist is perseverance.

  • We insisted. We refined our paradigm,

  • and after several months of training,

  • the otherwise paralyzed rat could stand,

  • and whenever she decided,

  • initiated full weight-bearing locomotion

  • to sprint towards the rewards.

  • This is the first recovery ever observed

  • of voluntary leg movement

  • after an experimental lesion of the spinal cord