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UF SCIENTIST: “BRAIN” IN A DISH ACTS AS AUTOPILOT, LIVING COMPUTER
Oct. 21, 2004
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GAINESVILLE, Fla. --- A University of Florida scientist has
grown a living “brain” that can fly a simulated plane, giving
scientists a novel way to observe how brain cells function as
a network.
The “brain” -- a collection of 25,000 living neurons, or nerve
cells, taken from a rat’s brain and cultured inside a glass
dish -- gives scientists a unique real-time window into the
brain at the cellular level. By watching the brain cells
interact, scientists hope to understand what causes neural
disorders such as epilepsy and to determine noninvasive ways
to intervene.
As living computers, they may someday be used to fly small
unmanned airplanes or handle tasks that are dangerous for
humans, such as search-and-rescue missions or bomb damage
assessments.
“We’re interested in studying how brains compute,” said Thomas
DeMarse, the UF professor of biomedical engineering who
designed the study. “If you think about your brain, and
learning and the memory process, I can ask you questions about
when you were 5 years old and you can retrieve information.
That’s a tremendous capacity for memory. In fact, you perform
fairly simple tasks that you would think a computer would
easily be able to accomplish, but in fact it can’t.”
While computers are very fast at processing some kinds of
information, they can’t approach the flexibility of the human
brain, DeMarse said. In particular, brains can easily make
certain kinds of computations – such as recognizing an
unfamiliar piece of furniture as a table or a lamp – that are
very difficult to program into today’s computers.
“If we can extract the rules of how these neural networks are
doing computations like pattern recognition, we can apply that
to create novel computing systems,” he said.
DeMarse experimental "brain" interacts with an F-22 fighter
jet flight simulator through a specially designed plate called
a multi-electrode array and a common desktop computer.
“It’s essentially a dish with 60 electrodes arranged in a grid
at the bottom,” DeMarse said. “Over that we put the living
cortical neurons from rats, which rapidly begin to reconnect
themselves, forming a living neural network – a brain.”
The brain and the simulator establish a two-way connection,
similar to how neurons receive and interpret signals from each
other to control our bodies. By observing how the nerve cells
interact with the simulator, scientists can decode how a
neural network establishes connections and begins to compute,
DeMarse said.
When DeMarse first puts the neurons in the dish, they look
like little more than grains of sand sprinkled in water.
However, individual neurons soon begin to extend microscopic
lines toward each other, making connections that represent
neural processes. “You see one extend a process, pull it back,
extend it out – and it may do that a couple of times, just
sampling who’s next to it, until over time the connectivity
starts to establish itself,” he said. “(The brain is) getting
its network to the point where it’s a live computation device.”
To control the simulated aircraft, the neurons first receive
information from the computer about flight conditions: whether
the plane is flying straight and level or is tilted to the
left or to the right. The neurons then analyze the data and
respond by sending signals to the plane’s controls. Those
signals alter the flight path and new information is sent to
the neurons, creating a feedback system.
“Initially when we hook up this brain to a flight simulator,
it doesn’t know how to control the aircraft,” DeMarse
said. “So you hook it up and the aircraft simply drifts
randomly. And as the data comes in, it slowly modifies the
(neural) network so over time, the network gradually learns to
fly the aircraft.”
Although the brain currently is able to control the pitch and
roll of the simulated aircraft in weather conditions ranging
from blue skies to stormy, hurricane-force winds, the
underlying goal is a more fundamental understanding of how
neurons interact as a network, DeMarse said.
“There’s a lot of data out there that will tell you that the
computation that’s going on here isn’t based on just one
neuron. The computational property is actually an emergent
property of hundreds or thousands of neurons cooperating to
produce the amazing processing power of the brain.”
With Jose Principe, a UF distinguished professor of electrical
engineering and director of UF's Computational
NeuroEngineering Laboratory, DeMarse has a $500,000 National
Science Foundation grant to create a mathematical model that
reproduces how the neurons compute.
These living neural networks are being used to pursue a
variety of engineering and neurobiology research goals, said
Steven Potter, an assistant professor in the Georgia
Tech/Emory Department of Biomedical Engineering who uses
cultured brain cells to study learning and memory. DeMarse was
a postdoctoral researcher in Potter’s laboratory at Georgia
Tech before he arrived at UF.
“A lot of people have been interested in what changes in the
brains of animals and people when they are learning things,”
Potter said. “We’re interested in getting down into the
network and cellular mechanisms, which is hard to do in living
animals. And the engineering goal would be to get ideas from
this system about how brains compute and process information.”
Though the ”brain” can successfully control a flight
simulation program, more elaborate applications are a long way
off, DeMarse said.
“We’re just starting out. But using this model will help us
understand the crucial bit of information between inputs and
the stuff that comes out,” he said. “And you can imagine the
more you learn about that, the more you can harness the
computation of these neurons into a wide range of
applications.” |
