Scientists have devised a technique to watch, in real time, the dynamic ebb and flow of brain connections in young mouse models of fragile X syndrome. The findings appeared in June in the Journal of Neuroscience.

Postmortem tissue from people with the syndrome and static images of the brains of young mouse models³ have both shown that fragile X brains look much less mature than do the brains of control animals. For example, they have abnormally long and dense dendritic spines — the slender neuronal projections that receive electrical messages from other cells and that are heavily pruned during development.

The new work shows, however, that dendrites in the fragile X brain appear more normal than those studies suggested.

“This is a big deal,” notes Anis Contractor, assistant professor of physiology at Northwestern University, who was not involved in the study. “It contradicts the dogma in the field that in all parts of the cortex [in fragile X] there’s this immature, delayed development.”

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SFARI, July 2010.

Brains of children with fragile X syndrome go through an abnormal trajectory of development in the first few years of life, according to the first study to track how the disease unfolds in the brain. The findings were published in May in the Proceedings of the National Academy of Sciences.

Fragile X syndrome — a genetic disease that causes mental retardation and often autism — results from the complete loss of fragile X mental retardation protein, or FMRP, which is important for many brain processes. By comparing children with the syndrome and healthy controls, the new findings present a picture of when and where FMRP is expressed during early development.

“This is beautiful work,” says April Benasich, director of the Infancy Studies Laboratory at Rutgers University, who was not involved in the study. “The ability to link individual differences in the structure of the brain to some genetic precursor is extremely powerful.”

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SFARI, July 2010.