US researchers have simulated half a virtual mouse brain on a
supercomputer.
The scientists ran a "cortical simulator" that was as big and as
complex as half of a mouse brain on the BlueGene L
supercomputer.
In other smaller simulations the researchers say they have seen
characteristics of thought patterns observed in real mouse
brains.
Now the team is tuning the simulation to make it run faster and to
make it more like a real mouse brain.
Life signs
Brain tissue presents a huge problem for simulation because of its
complexity and the sheer number of potential interactions between
the elements involved.
The three researchers, James Frye, Rajagopal Ananthanarayanan, and
Dharmendra S. Modha, laid out how they went about it in a very
short research note entitled "Towards Real-Time, Mouse-Scale
Cortical Simulations".
Half a real mouse brain is thought to have about eight million
neurons each one of which can have up to 8,000 synapses, or
connections, with other nerve fibres.
Modelling such a system, the trio wrote, puts "tremendous
constraints on computation, communication and memory capacity of
any computing platform".
The team, from the IBM Almaden Research Lab and the University of
Nevada, ran the simulation on a BlueGene L supercomputer that had
4096 processors, each one of which used 256MB of memory.
Using this machine the researchers created half a virtual mouse
brain that had 8,000 neurons that had up to 6,300 synapses.
The vast complexity of the simulation meant that it was only run
for ten seconds at a speed ten times slower than real life - the
equivalent of one second in a real mouse brain.
On other smaller simulations the researchers said they had seen
"biologically consistent dynamical properties" emerge as nerve
impulses flowed through the virtual cortex.
In these other tests the team saw the groups of neurons form
spontaneously into groups. They also saw nerves in the simulated
synapses firing in a ways similar to the staggered, co-ordinated
patterns seen in nature.
The researchers say that although the simulation shared some
similarities with a mouse's mental make-up in terms of nerves and
connections it lacked the structures seen in real mice
brains.
Imposing such structures and getting the simulation to do useful
work might be a much more difficult task than simply setting up the
plumbing.
For future tests the team aims to speed up the simulation, make it
more neurobiologically faithful, add structures seen in real mouse
brains and make the responses of neurons and synapses more
detailed.
Mouses and rats are really useful research "tools" for scientists
From:BBC NEWS