[Paleopsych] Economist: Modelling the brain: Grey matter, blue matter
checker at panix.com
Wed Jun 15 19:46:53 UTC 2005
Modelling the brain: Grey matter, blue matter
The first serious attempt to build a computer model of the brain has
THE most complex object known to humanity is the human brain--and not
only is it complex, but it is the seat of one of the few natural
phenomena that science has no purchase on at all, namely
consciousness. To try to replicate something that is so poorly
understood may therefore seem like hubris. But you have to start
somewhere, and IBM and the Ecole Polytechnique Fédérale de Lausanne
(EPFL), in Switzerland, propose to start by replicating "in silico",
as the jargon has it, one of the brain's building blocks.
In a partnership announced on June 6th, the two organisations said
they would be working together to build a simulation of a structure
known as a neocortical column on a type of IBM supercomputer that is
currently used to study the molecular functioning of genes. If that
works, they plan to use future, more powerful computers to link such
simulated columns together into something that mimics a brain.
In a real brain, a neocortical column is a cylindrical element about a
third of a millimetre in diameter and three millimetres long,
containing some 10,000 nerve cells. It is these columns, arranged side
by side like the cells of a honeycomb, which make up the famous "grey
matter" that has become a shorthand for human intelligence. The Blue
Gene/L supercomputer that will be used for the simulation consists of
enough independent processors for each to be programmed to emulate an
individual nerve cell in a column.
The EPFL's contribution to the Blue Brain Project, as it has
inevitably been dubbed, will be to create a digital description of how
the columns behave. Its Brain Mind Institute has what is generally
regarded as the world's most extensive set of data on the machinations
of the neocortex--the columns' natural habitat and the part of the
brain responsible for learning, memory, language and complex thought.
This database will provide the raw material for the simulation.
Biologists and computer scientists will then collaborate to connect
the artificial nerve cells up in a way that mimics nature. They will
do so by assigning electrical properties to them, and telling them how
to communicate with each other and how they should modify their
connections with one another depending on their activity.
That will be no mean feat. Even a single nerve cell is complicated,
not least because each one has about 10,000 connections with others.
And nerve cells come in great variety--relying, for example, on
different chemical transmitters to carry messages across those
connections. Eventually, however, a digital representation of an
entire column should emerge.
This part of the project is expected to take two to three years. From
then on, things will go in two directions simultaneously. One will be
to "grow" more columns (the human brain contains about 1m of them) and
get them to interact with one another. The second will be to work at a
more elementary level--that is, to simulate the molecular structure of
the brain, and to look at the influence of gene expression on brain
Assuming that the growth of computing power continues to follow
Moore's Law, Charles Peck, the leader of IBM's side of the
collaboration, reckons it should be feasible to emulate an entire
human brain in silico this way in ten to 15 years. Such an artificial
brain would, of course, be a powerful research tool. It would allow
neurological experiments that currently take days in a "wet lab" to be
conducted in seconds. The researchers hope, for instance, that their
simulated brain will reveal the secrets of how certain psychiatric and
neurological disorders develop. But that is probably not the real
reason for doing it. The most interesting questions, surely, are
whether such an artificial brain will be intelligent, or conscious, or
Rhapsody in blue?
Some academics, such as Roger Penrose of Oxford University, argue that
brains do not work in a way comparable with a computer, so any kind of
simulation that is built on digital architecture and uses traditional
programming techniques is doomed to failure. Dr Penrose thinks that
exotic quantum processes are involved in the generation of
consciousness. The "Blue Brain" project will help to determine whether
he is right or wrong.
Henry Markram, the boss of the Brain Mind Institute, and the leader of
the EPFL's side of the collaboration, stresses that Blue Brain's
formal goal is not to build an artificial intelligence system, such as
a neural network. Nor is it to create a conscious machine. The goal is
merely to build a simulacrum of a biological brain. If the outputs
produced by the simulation in response to particular inputs are
identical to those in animal experiments, then that goal will have
been achieved. On the other hand, he also says, "I believe the
intelligence that is going to emerge if we succeed in doing that is
going to be far more than we can even imagine." Watch this space.
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