[Paleopsych] New Scientist: The word: Connectome
checker at panix.com
Thu Nov 17 20:42:23 UTC 2005
The word: Connectome
>From issue 2525 of New Scientist magazine, 12 November 2005, page 62
[Happy to comply with your request for the full article, Brian.]
THE human brain is a fantastic maze of connections, a vast network of networks
that circulates information and determines how we think and act. One of the
many big puzzles left in neurology is working out which parts of the brain are
connected - and how the networks function.
That's why top neuroscientist Olaf Sporns of Indiana University at Bloomington
and his team are hoping for some lively debate about their new blueprint to map
those connections. Sporns is calling it "the human connectome" after the
billion-dollar human genome project, but it's bound to be far more
Why? Well, the genome is one-dimensional, while the connectome will be
four-dimensional (three space, one time). The information needed to build the
connectome is also far more elusive. Our brains contain roughly 10^11 neurons,
with an estimated 10^14 possible connections. The magnitude of these numbers
makes it impossible for the connectome to map the brain at the level of single
neurons and synapses. Luckily, that may not be necessary because nerve cells
tend to act in groups.
What will the connectome look like? At first, it will be a huge set of numbers
from which cognitive patterns can be deduced. Input the coordinates of two
brain regions and the connectome will give the probability of those two parts
talking to one another. The coordinates refer to voxels (3D pixels), which is
useful because it's how neuroscientists map the brain, so the connectome can be
cross-referenced to other data. But in future, with the right technology, we
could build a dynamic 4D model with the brain's connections operating in real
time. Just think: one little thought, and the model would light up like a
Christmas tree! "The brain is a maze of connections, a vast network of
So how much is known already? There are a few precedents: large-scale
connection patterns have been mapped for animal brains such as the macaque, cat
and rat. But for human connections, researchers will need sophisticated imaging
techniques that show how the brain's anatomy relates to its dynamic function.
For that, they'll build on existing techniques such as diffusion tensor
imaging, functional MRI and EEGs.
They'll also need the snazzy software used to map connections in the web and
other large networks. Not to mention computers such as the giant 10 petaflop
baby that Japan is planning.
The pay-off? Oh, just a few useful things such as finding out much more about
how the different regions of the brain interact when we think or act, what
injuries to particular regions do, and how our cognitive networks differ from
those of other species.
Not surprisingly, the connectome will demand a worldwide effort by anatomists,
brain imagers and computational scientists. And more billions than the genome
project. Sporns thinks a first draft of the connectome could be ready in a few
years. Watch this space.
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