Dr Derek Muller
Sometimes with the right motivation, anything is possible. Mm... tres bien!

NARRATION
The main function of the spinal cord is to transmit neurosignals - or messages - between the brain and the rest of the body. So when the spinal cord is severed or crushed, these messages can't get past the injury. The result is often chronic paralysis. Research in this area generally focuses on regenerating damage nerve fibres. But here in Lausanne they're taking a different approach.

Prof Gregoire Courtine
Bonjour, Derek.

Dr Derek Muller
Bonjour.

Prof Gregoire Courtine
Welcome in the lab.

Dr Derek Muller
Ah, thank you.

NARRATION
Professor Courtine's work with rats is producing remarkable results.

Prof Gregoire Courtine
So I thought, 'Can we actually deliver to the spinal cord the kind of information that the brain would deliver naturally in order to work?'

NARRATION
The rats have their spinal cords cut in two places. Although not completely severed, signals can't get past the lesion, leaving the rats paralysed. To reactivate the healthy but disconnected neuro-cells below the injury, the researchers administer a cocktail of synthetic neurotransmitters, followed by electrical stimulation.

Rubia van den Brand
I'm plugging in the cable that connects to the electrodes on the spinal cord, so we can provide the stimulation to the spinal cord.

Dr Derek Muller
OK. So they're cables that run down the spinal cord?

Rubia van den Brand
It actually runs under the skin and then it's sutured on top of the spinal cord.

NARRATION
This electrochemical combination mimics the input of the brain and reawakens the spinal cord below the lesion.

Prof Gregoire Courtine
I start the treadmill. Immediately she will start walking. It's amazing, right?

NARRATION
The result? After a few weeks of training, and while on the treadmill, the rat is, incredibly, able to walk again.

Prof Gregoire Courtine
This animal was completely paralysed five minutes ago and now she's doing continuous stepping on the treadmill. And now we go at training speed. Immediately, the animal is capable of... like literally is sprinting on the treadmill. Look at this - you cannot even do it yourself. I will stop the treadmill. She stands. Immediately!

NARRATION
But this is happening without the involvement of the brain. At this stage, the rat's stepping is stimulated by the treadmill. The legs are moving independently of the brain, so the movement is completely involuntary.

Prof Gregoire Courtine
You can train the rats on this treadmill for two month. You will not see recovery of voluntary control. Why? The brain is not involved. There's no motivation to walk...

NARRATION
Motivation is the key to restoring voluntary movement. So this is where the irresistible Swiss chocolate comes in.

Dr Derek Muller
I brought a chocolate eclair. I ate half, but the other half is for the rat.

Rubia van den Brand
Yeah, see?

Dr Derek Muller
She does like it.

Rubia van den Brand
She likes it.

Prof Gregoire Courtine
We have a combination of like actually yoghurt and chocolate, which the rat love.

NARRATION
This reward-based training, without a treadmill, was the focus of the next phase of research.

Rubia van den Brand
We have to get her in the right position.

NARRATION
They designed a special robot which only supports the paralysed rat but doesn't propel it forward.

Prof Gregoire Courtine
This means that the rats really need to generate the propulsive forces to go towards the reward, which is the chocolate.

Rubia van den Brand
So the rat is asked to go push herself forward, but she does get a little bit of help up and down.

NARRATION
The rats have again been given electrochemical stimulants, but, without the treadmill, the rat has to decide for itself if it wants to walk.

Prof Gregoire Courtine
When you want the animal to participate very actively - we're talking about the championships for rehabilitation - you need to motivate the rat at any cost.

Rubia van den Brand
Come, come, come, come!

NARRATION
So Rubia does whatever it takes to coax the rat to walk.

Rubia van den Brand
Come on, jump! Go forwards! Come on! Push! Push! Push, sweetie. Come on! Keep going! Keep going!

NARRATION
The rat is now walking when IT wants to, which means the brain signals are getting through to the previously paralysed limbs.

Dr Derek Muller
Wow, she's done really well.

NARRATION
The rat's spinal cord seems much more capable of rewiring itself than anyone expected. In one of the most extensive examples observed, it's been able to detour around the injury and reconnect the dormant neural network.

Prof Gregoire Courtine
What we observe is that the cut fibres basically grow and deliver to this neural network below the injury - enough information - we don't know what kind, but sufficient information from the brain to have voluntary control.

(Electrical crackling)

NARRATION
What we're hearing is evidence of the rat making the decision to walk.

Dr Jack DiGiovanna
The popping sound is a neuron firing, and here she's just standing, but you'll see once she starts walking, there's a pretty clear pattern of the activity of the neuron with the rat stepping.

NARRATION
It's showing that the movement is voluntary.

Dr Jack DiGiovanna
And that's really cool. That was really exciting the first time that happened, because, you know, we had this idea that the brain should be involved, but it hadn't been proven.

Rubia van den Brand
Come, come, come. (Clicks tongue)

Dr Jack DiGiovanna
And there's a whole team of people working and everybody's pushing the rat and everybody's all, 'Go, go, go!' And I could hear it before it happened and I really knew, 'OK, it's gonna work this time.'

Rubia van den Brand
Perfect!

NARRATION
With half of all human spinal injuries leading to chronic paralysis, Professor Courtine's research gives new hope to those affected.

Prof Gregoire Courtine
So, of course, the next obvious and exciting goal is to try this type of intervention in humans. It's difficult to say what this will achieve in humans. But, you know, it's a very promising new path.

STORY CONTACTS

Prof. Grégoire Courtine 
International Paraplegic Foundation Chair in Spinal Cord Repair
Center for Neuroprosthetics and Brain Mind Institute

Dr Rubia van de Brand 
Movement and Posture Therapist

Dr Jack Digiovanna 
Neuroengineer