Some neuroscientists believe the brain is laid out like a grid, and certain parts of the grid perform specific functions. There are others who are a little more progressive; who believe the brain is more complex than that. Although some parts of the brain is used for specific functions, the plasticity allows an overlap, or the ability to repair and change those connections so other brain areas can perform functions that their designated areas is not able to.
According to experts, the brain is the most complex object in the known universe. It is made up of billions of connecting nerve fibers that looks like a tangled bowl of spaghetti.This idea, if you listen to Van Wedeen and his research team from Massachusetts General Hospital in Boston, is a stretch from reality.
Affording to Weeden, when you use a magnetic resonance imaging scanner (MRI), and straighten out the folds, the brain actually consists of a grid of fibers that appear to be three-dimensional.
If this proves to be true it could sort the mysteries surrounding brain development and evolution, as well as link neurological and psychiatric disorders to abnormalities in brain structure. Have Wedeen and his team uncovered the fundamental organizing principle for the brain, or is what they believe to be a grid simply another part of a more complex system?
David Van Essen of Washington University in St. Louis, is one of the leaders of the Human Connection Project, a group of researchers who are trying to come up with a comprehensive map of the brain’s neural connections.
Brain-mappers have been using a technique for years called diffusion tensor imaging. This process tracks the diffusion of water through body tissues to follow fibers through the brain in order to see how one region can connect to another. Wedeen and his group used a similar method, called diffusion spectrum MRI, which highlights the areas where the nerve fibers cross.
In their study they used primates and humans, and found sheets of parallel fibers running at 90-degree angles to each other, like fabric weave. These sheets are arranged at right angles to each other, giving a three-dimensional grid.
Lower primates, such as the Galogo bushbaby, showed this pattern more obviously. As you move up the primate family tree there are more folds and curves present, but the same basic grid structure stays the same.
If this is true, Wedeen says, this would explain how neurons wire themselves together, and know in which direction to send the information they have. He likens the structure to the grids of New York City streets, which gives simple directions for a specific destination. It could also explain how complex brains evolved. According to Wedeen, if the brain were a tangle of connections it would be difficult to see mutations that would lead to connectivity changes.”Try going into your basement and randomly rewiring your house,”Wedeen says. “In a grid structure, it’s much easier to imagine changes in the developmental code producing adaptive changes in behavior.”He continues, “Similarly, a readily re-wired grid helps to explain how people are able to recover from brain injuries by making new connections to regain lost functions.”
“The grid is an attractive idea to many neuroscientists, but some doubt that it is the whole story,”says Van Essen. “My concern is that they may have oversimplified and over-generalized in their optimism that this will apply brain-wide.” He believes that the brain also contains fibers that are criss-crossing in other orientations.
Specialist in diffusion MRI at the King’s College London Institute of Psychiatry, Marco Catani, thinks that Wedeen’s method may be missing fibers crossing at angles less than about 70 degrees, which he said he and his team have seen using a different diffusion imaging technique.
Wedeen believes his own team would have seen fibers crossing at shallower angles, if they were common. He said his team used a diffusion imaging technique in their research and received similar results.
There obviously are more studies in the future to answer this question definitively.
About the author:
Ron White is a two-time U.S.A. Memory Champion and memory training expert. As a memory keynote speaker he travels the world to speak before large groups or small company seminars, demonstrating his memory skills and teaching others how to improve their memory, and how important a good memory is in all phases of your life. His CDs and memory products are also available online at BrainAthlete.com.
Sources:
New Science – Human brain organized like a 3D ‘New York City’ grid: http://www.newscientist.com/article/dn21647-human-brain-organised-like-a-3d-new-york-city-grid.html
