In August 2008, MIT Technology Review reported on how new imaging
technologies are revealing the intricate architecture of the brain, by
creating a series of highly-detailed, and never seen before, blueprints of
its dense connectivity.
The typical brain scan shows a muted gray
rendering of the brain, easily distinguished by a series of convoluted
folds. But according to Van Wedeen, an Associate Professor in Radiology at
Harvard, that image is just a shadow of the real brain. A new technique
called Diffusion spectrum imaging (DSI) uses magnetic resonance signals to
track the movement of water molecules in the brain: water diffuses along the
length of neural wires, called axons. Scientists can use these diffusion
measurements to map the wires, creating a detailed map of the brain's
The first image shows half the cerebral hemisphere of a macaque
monkey. The blue bundle of fibers running horizontally across the middle
of the image is called the cingulum bundle, described by Wedeen as "a
multilane highway" that runs from the prefrontal cortex, which is involved
in planning and higher cognitive function, to the parietal cortex, which is
mainly involved in synthesizing sensory information. While it looks quite
complicated, it represents only a fraction - about 10 to 20 percent - of the
wiring in that part of the brain.
On the second image one can see some of
monkey brain's anatomical structures. The treelike shape at lower left,
for example, shows the longitudinal fibers of the cerebellum, a brain area
that plays an important role in coordination and motor control, as well as
in the integration of information from different senses. It's important to
point out that even if these images look extremely dense, "The human brain
would look 25 times as complicated," says Wedeen.
You can also see a short but powerfull video on a normal human subject using the same technique, and a related article with a rich gallery of images.