Next week at the World Cup, a
paralyzed volunteer from the Association for Assistance to Disabled
Children will walk onto the field and open the tournament with a
ceremonial kick. This modern miracle is made possible by a robotic
exoskeleton that will move the user's limbs, taking commands directly
from his or her thoughts.
This demonstration is the debut of the Walk Again Project,
a consortium of more than 150 scientists and engineers from around the
globe who have come together to show off recent advances in the field of
brain machine interfaces, or BMI. The paralyzed person inside will be
wearing an electroencephalographic (EEG) headset that records brainwave
activity. A backpack computer will translate those electrical signals
into commands the exoskeleton can understand. As the robotic frame
moves, it also sends its own signals back to the body, restoring not
just the ability to walk, but the sensation as well.
Just how well the wearer will walk and kick are uncertain. The project has been criticized by other neuroscientists as an exploitative spectacle that uses the disabled to promote research which may not be the best path
for restoring health to paralyzed patients. And just weeks before the
project is set to debut on television to hundreds of millions of fans,
it still hasn’t been tested outdoors and awaits some final pieces and
construction. It's not even clear which of the eight people from the
study will be the one inside the suit.
The point of the project is not
to show finished research, however, or sell a particular technology.
The Walk Again Project is meant primarily to inspire. It's a
demonstration that we’re on the threshold of achieving science fiction:
technologies that will allow humans to truly step into the cyborg era.
It’s only taken a little over two centuries to get there.
The past
Scientists have been studying
the way electricity interacts with our biology since 1780, when Luigi
Galvani made the legs of a dead frog dance by zapping them with a spark,
but the modern history behind the technology that allows our brains to
talk directly to machines goes back to the 1950s and John Lilly. He
implanted several hundred electrodes into different parts of a monkey’s
brain and used these implants to apply shocks, causing different body
parts to move. A decade later in 1963, professor Jose Delgado of Yale
tested this theory again like a true Spaniard, stepping into the ring to
face a charging bull, which he stopped in its tracks with a zap to the brain.
In 1969, professor Eberhard Fetz was able to isolate and record the
firing of a single neuron onto a microelectrode he had implanted into
the brain of a monkey. Fetz learned that primates could actually tune
their brain activity to better interact with the implanted machine. He
rewarded them with banana pellets every time they triggered the
microelectrode, and the primates quickly improved in their ability to
activate this specific section of their brain. This was a critical
observation, demonstrating brain’s unique plasticity, its ability to
create fresh pathways to fit a new language.
Today, BMI research has
advanced to not only record the neurons firing in primates’ brains, but
to understand what actions the firing of those neurons represent. "I
spend my life chasing the storms that emanate from the hundreds of
billions of cells that inhabit our brains," explained Miguel Nicolelis, PhD, one of the founders of Center for Neuroengineering
at Duke University and the driving force behind the Walk Again Project.
"What we want to do is listen to these brain symphonies and try to
extract them from the messages they carry."
Nicolelis and his colleagues at
Duke were able to record brain activity and match it to actions. From
there they could translate that brain activity into instructions a
computer could understand. Beginning in the year 2000, Nicolelis and
his colleagues at Duke made a series of breakthroughs. In the most well
known, they implanted a monkey with an array of microelectrodes that
could record the firing of clusters of neurons in different parts of the
brain. The monkey stood on a treadmill and began to walk. On the other
side of the planet, a robot in Japan received the signal emanating from
the primate’s brain and began to walk.
Primates
in the Duke lab learned to control robotic arms using only their
thoughts. And like in the early experiments done by Fetz, the primates
showed a striking ability to improve the control of these new limbs.
"The brain is a remarkable instrument," says professor Craig Henriquez,
who helped to found the Duke lab. "It has the ability to rewire itself,
to create new connections. That’s what gives the BMI paradigm its power.
You are not limited just by what you can physically engineer, because
the brain evolves to better suit the interface."
The present
After his success with
primates, Nicolelis was eager to apply the advances in BMI to people.
But there were some big challenges in the transition from lab animals to
human patients, namely that many people weren’t willing to undergo
invasive brain surgery for the purposes of clinical research. "There is
an open question of whether you need to have implants to get really fine
grained control," says Henriquez. The Walk Again Project hopes to
answer that question, at least partially. While it is based on research
in animals that required surgery, it will be using only external EEG
headsets to gather brain activity.
The fact that these patients
were paralyzed presented another challenge. Unlike the lab monkeys, who
could move their own arms and observe how the robot arm moved in
response, these participants can’t move their legs, or for many, really
remember the subconscious thought process that takes place when you want
to travel by putting one foot in front of the other. The first step was
building up the pathways in the brain that would send mental commands
to the BMI to restore locomotion.
To train the patients in this
new way of thinking about movement, researchers turned to virtual
reality. Each subject was given an EEG headset and an Oculus Rift.
Inside the head-mounted display, the subjects saw a virtual avatar of
themselves from the waist down. When they thought about walking, the
avatar legs walked, and this helped the brain to build new connections
geared towards controlling the exoskeleton. "We also simulate the
stadium, and the roar of the crowd," says Regis Kopper, who runs Duke’s
VR lab. "To help them prepare for the stress of the big day."
Once
the VR training had established a baseline for sending commands to the
legs, there was a second hurdle. Much of walking happens at the level of
reflex, and without the peripheral nervous system that helps people
balance, coordinate, and adjust to the terrain, walking can be a very
challenging task. That’s why even the most advanced robots have trouble navigating stairs
or narrow hallways that would seem simple to humans. If the patients
were going to successfully walk or kick a ball, it wasn’t enough that
they be able to move the exoskeleton’s legs — they had to feel them as
well.
The breakthrough was a special
shirt with vibrating pads on its forearm. As the robot walked, the
contact of its heel and toe on the ground made corresponding sensations
occur along parts of the right and left arms. "The brain essentially
remapped one part of the body onto another," says Henriquez. "This
restored what we call proprioception, the spacial awareness humans need
for walking."
In recent weeks all eight of
the test subjects have successfully walked using the exoskeleton, with
one completing an astonishing 132 steps. The plan is to have the
volunteer who works best with the exoskeleton perform the opening kick.
But the success of the very public demonstration is still up in the air.
The suit hasn’t been completely finished and it has yet to be tested in
an outdoor environment. The group won't confirm who exactly will be
wearing the suit. Nicolelis, for his part, isn’t worried. Asked when he
thought the entire apparatus would be ready, he replied: "Thirty minutes
before."
The future
The Walk Again project may be
the most high-profile example of BMI, but there have been a string of
breakthrough applications in recent years. A patient at the University of Pittsburgh
achieved unprecedented levels of fine motor control with a robotic arm
controlled by brain activity. The Rehabilitation Institute of Chicago
introduced the world’s first mind controlled prosthetic leg. For now the use of advanced BMI technologies is largely confined to academic and medical research, but some projects, like DARPA’s Deka arm,
have received FDA approval and are beginning to move into the real
world. As it improves in capability and comes down in cost, BMI may
open the door to a world of human enhancement that would see people
merging with machines, not to restore lost capabilities, but to augment
their own abilities with cyborg power-ups.
"From the standpoint of
defense, we have a lot of good reasons to do it," says Alan Rudolph, a
former DARPA scientist and Walk Again Project member. Rudolph, for
example, worked on the Big Dog,
and says BMI may allow human pilots to control mechanical units with
their minds, giving them the ability to navigate uncertain or dynamic
terrain in a way that has so far been impossible while keeping soldiers
out of harms way. Our thoughts might control a robot on the surface of
Mars or a microsurgical bot navigating the inside of the human body.
There is a subculture of DIY biohackers and grinders
who are eager to begin adopting cyborg technology and who are willing,
at least in theory, to amputate functional limbs if it’s possible to
replace them with stronger, more functional, mechanical ones. "I know
what the limits of the human body are like," says Tim Sarver, a member
of the Pittsburgh biohacker collective Grindhouse Wetwares. "Once you’ve
seen the capabilities of a 5000psi hydraulic system, it’s no
comparison."
For now, this sci-fi vision
all starts with a single kick on the World Cup pitch, but our inevitable
cyborg future is indeed coming. A recent demonstration
at the University of Washington enabled one person’s thoughts to
control the movements of another person’s body — a brain-to-brain
interface — and it holds the key to BMI’s most promising potential
application. "In this futuristic scenario, voluntary electrical brain
waves, the biological alphabet that underlies human thinking, will
maneuver large and small robots, control airships from afar," wrote
Nicolelis. "And perhaps even allow for the sharing of thoughts and
sensations with one individual to another."