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January 4, 2011

Brain Connections

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The Whole Brain Atlas

The Brain Wiring Test

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Scientists have discovered that not only does your brain go through growth spurts; it also goes though periods of pruning. This ScienCentral News video has more.

Branching Out

What goes on in your brain while your're learning? Two scientists offer a sneak peak underneath our thinking caps.

In the brain, nerve cells, or neurons, grow new connections, which resemble branches on a tree. These branches send and receive signals, and their growth is vital to normal brain function; the more branches there are, the more sites by which a neuron can send and receive information.

"While you're an adult, your brain doesn't just stop growing and doesn't just stop making new connections. It actually forms new connections all the time," says Bonnie Firestein, professor of cell biology and neuroscience at Rutgers University. "We know that when you're learning something, you have new connections made. So, the brain is constantly growing and constantly changing."

Firestein has found that a brain chemical called cypin helps nerve cells sprout new branches of communication, and the more cypin you have, the more branches you have. "We know that if you decrease cypin, in our system, you have a lower amount of branches," she explains. "So, right now…we just know that cypin is really important for making the correct number of branches, and that if you increase cypin you get more branches, and that it's been shown that more branches generally corresponds to learning and memory. When you're learning, you're making the nerve cells active, you're having increases in cypin, and then you're having more branches or more wiring so that you can learn."

pointing to branches
But there is such a thing as too many branches, says Jay Giedd, chief of brain imaging at the National Institute of Mental Health (NIMH) , and the brain knows how to get rid of excess.

"How does the brain, the most complicated three-pound mass of matter in the known universe, become the brain? Through simply but powerful processes," Giedd explains. "The first is overproduction. Way more brain cells and connections form than can possibly survive. And the second process is war, or competitive elimination. They fight it out for survival. Only a small percentage of the connections can make it, but it's nature's way of making sure that those [that] do survive are healthy and robust and strong."

Studying MRI scans of children and teenagers over a ten-year period, Giedd found that nerve cells in young brains undergo two waves of intense branching, the first in the womb and up to the first two years of life, and the other peaking at about age eleven or twelve, followed by a self-pruning period during the teen years.

Both Firestein and Giedd point out that our brains continue to develop throughout our lives, just not at the same rate as in children. And both say understanding how the brain develops could lead to new therapies for the diseases that affect it, like autism and Alzheimer's.

This research appeared in the May 25, 2004 issue of Proceedings of the National Academy of Sciences and the February, 2004 issue of Nature Neuroscience. It was funded by the National Institutes of Health; Busch Biomedical Grants; New Jersey Commission on Spinal Cord Research Grant and the National Science Foundation.

       email to a friend by Karen Lurie

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