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Noisy Brain Signals (video)
February 25, 2003

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Interviewees: Dian Bolling, Mother; William Greenough, University of Illinois.

Video is 1 min 41 sec long. Please be patient while it loads enough to start playing.

Produced by Sanjanthi Velu

Copyright © ScienCentral, Inc., with additional footage shot for FRAXA by Debbie Stevenson, and images from Bill Greenough and Aaron Grossman, University of Illinois.

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Elsewhere on the web

The National Fragile X Foundation

Conquer Fragile X Foundation

Fragile X Syndrome - GeneReviews

Fragile X syndrome is a type of mental retardation that affects children. Neuroscientists studying the brains of adult patients have found that there are extra connections in the Fragile X brain.

And as this ScienCentral News video reports, more is not a good thing.

Noisy Brains

Fragile X Syndrome is a type of mental retardation that seems to affect boys more than girls.

“Patients with Fragile X Syndrome show a broad spectrum of cognitive impairment,” says William T. Greenough. “The effects are manifested in everything from language, to motor skills. They are retarded; they are typically well behind in school; and they are physically often very, very clumsy. There is also often a tendency towards autistic behavior.” Greenough is a professor of psychology, psychiatry, and cell and structural biology at the Beckman Institute and the University of Illinois.

Since 1991, the scientific community has known that the malfunctioning of a gene called FMR1 blocks the production of the Fragile X protein, and that this is somehow related to Fragile X Syndrome. But according to Michael Tranfaglia, Medical Director of FRAXA (a non-profit, family-run, Fragile X research foundation) it is still unclear how the loss of this protein actually causes the specific symptoms of this syndrome.

To see what is going on in the Fragile X brain, Greenough and his team studied brain samples from deceased adult Fragile X sufferers and compared them to brains from deceased normal adults. They found something abnormal about the synapses in the Fragile X brains. “Synapses are the points at which nerve cells, or neurons, communicate with one another.” Greenough explains. “Any time one nerve cell sends a signal to another nerve cell, it does so through a synapse.”

Researchers were surprised to find that Fragile X patients had more synapses than the unaffected individuals. Greenough says they also found that the synapses were “misshapen, elongated, thin and abnormal.” He believes that these extra, abnormal connections could be creating more “noise” than normal signals in the brain.

Greenough explains that typically they would have expected more synapses or connections to lead to “a more intelligent brain.” But in this case, more is not better. They wondered why Fragile X patients had more synapses.

normal neuron vs. fragile X neuron - larger
A normal vs. a Fragile X neuron
image: Bill Greenough, Aaron Grossman

Greenough says that it’s important to understand that normal brains produce extra synapses to start with. That is, in early childhood the brain is programmed to produce more synapses than it typically needs. But during development the synapses that are used and have specific purposes are kept, while those that aren't are pruned away, “so that you have fewer synapses in adulthood than you had in childhood.”. The pruning process eliminates the extra synapses or connections that are not serving any purpose, and thereby keeps the brain efficient.

He and his team confirmed that the pruning process was defective in the case of Fragile X patients. So synapses that should have been pruned were not. Greenough also points out that the over-abundance of synapses actually distinguishes Fragile X from other types of mental retardation in that, “almost all other mental retardations actually involve brains that have fewer synapses. In Fragile X, by contrast—by surprising contrast—there actually are more synapses.”

There is currently no effective treatment for Fragile X Syndrome. Researchers are hopeful that studies like Greenough’s may help them come closer to testing drugs to treat, reverse or rehabilitate such abnormalities in the brain.

The findings were part of a study presented at the 2003 American Academy for the Advancement of Science meeting held in Denver. The study was funded by grants from the National Institute Of Child Health And Human Development, National Institute Of Mental Health, FRAXA Research Foundation, and the National Alliance For Research On Schizophrenia And Depression (NARSAD).

by Sanjanthi Velu

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