-
I am a neuroscientist
-
with a mixed background in physics and medicine.
-
My lab at Swiss Federal Institute of Technology
-
focuses on spinal cord injury,
-
which affect 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,
-
had 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 to 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 [??].
-
And when you go home,
-
think about 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 [??]
-
on opposite sides of the body.
-
They completely interrupt the communication
-
between the brain and the spinal cord,
-
thus leaving 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 are interrupted,
-
they are in a non-functional 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 knock at the door, 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 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 neural and in the spinal cord to fire,
-
and second, to mim 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 highly functional state.
-
Immediately, the paralyzed rat can stand.
-
As soon as the treadmill starts moving,
-
the animals show 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 takes 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 completed 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 a 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 how 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 neuroprostheses enable
-
highly functional state of the spinal locomotor networks.
-
The robot provides 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 more 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
-
leading to complete and permanent paralysis.
-
In fact --
-
(Applause)
-
Thank you.
-
In fact, not only the rat could initiate
-
and sustain locomotion on the ground,
-
they could even adjust leg movement,
-
for example, to resist gravity
-
in order to climb a staircase.
-
I can promise you this was
-
such an emotional moment in my laboratory.
-
It took us 10 years of hard work
-
to reach this goal.
-
But the remaining question was, how?
-
I mean, how is it possible?
-
And here, what we found
-
was completely unexpected.
-
This novel training paradigm
-
encouraged the brain to create new connections,
-
some relay circuits
-
that relay information from the brain
-
past the injury and restore cortical control
-
over the locomotor networks below the injury.
-
And here, you can see one such example,
-
where we label the fibers coming from the brain in red.
-
This blue neuron is connected with the locomotor center,
-
and what this constellation
-
of synaptive contacts means
-
is that the brain is reconnected with locomotor center
-
with only one relay neuron.
-
But the remodeling was not restricted
-
to the lesion area.
-
It occurred throughout the central nervous system,
-
including in the brain stem,
-
where we observed up to 300 percent increase
-
in the density of fibers coming from the brain.
-
We did not aim to repair the spinal cord,
-
yet we were able to promote
-
one of the more extensive remodeling
-
of external projection ever observed
-
in the central nervous system of adult mammal
-
after an injury.
-
And, you know, there is a very important message
-
hidden behind this discovery.
-
They are the result of a young team
-
of very talented people:
-
physical therapist, neurobiologist, neurosurgeon,
-
engineers of all kinds.
-
We have achieved together
-
what would have been impossible by single individuals.
-
This is truly a trans-disciplinary team.
-
They are work so close to each other
-
that there is almost like a transfer of DNA.
-
We are creating the next generation
-
of MDs and engineers,
-
get a bit of translating discoveries all the way
-
from bench to bedside.
-
And me?
-
I am only the maestro who orchestrated this beautiful symphony.
-
Now, I am sure you are all wondering, aren't you,
-
will this help injured people?
-
Me too, every day.
-
The truth is that we don't know enough yet.
-
This is certainly not a cure for spinal cord injury,
-
but I begin to believe that this may lead
-
to an intervention to improve recovery
-
and people's quality of life.
-
I would like you all
-
to take a moment and dream with me.
-
Imagine a person just suffered spinal cord injury.
-
After a few weeks of recovery,
-
we will implant a programmable [??]
-
to deliver a personalized pharmacological cocktail
-
directly into the spinal cord.
-
At the same time, we will implant an electrode array,
-
a sort of second skin
-
covering the area of the spinal cord controlling leg movement,
-
and this array is attached to an electrical pulse generator
-
that delivers stimulations that are tailored
-
to the person's needs.
-
This defines a personalized electrochemical neuroprosthesis
-
that will enable locomotion
-
during training with a newly designed supporting system.
-
And my hope is that after several months of training,
-
there may be enough remodeling of residual connection
-
to allow locomotion without the robot,
-
maybe even without pharmacology or stimulation.
-
My hope here is to be able to create
-
the personalized condition
-
to boost the plasticity of the brain
-
and the spinal cord.
-
And this is a radically new concept
-
that may apply to other neurological disorders.
-
What I termed "personalized neuroprosthetics,"
-
where by sensing and stimulating neural interfaces,
-
I implanted throughout the nervous system,
-
in the brain, in the spinal cord,
-
even in peripheral nerves,
-
based on patient-specific impairments.
-
But not to replace the lost function, no:
-
to help the brain help itself.
-
And I hope this enticed your imagination,
-
because I can promise to you
-
this is not a matter of whether this revolution will occur,
-
but when.
-
And remember, we are only as great
-
as our imagination, as big as our dream.
-
Thank you.
-
(Applause)