By pinpointing specific sites in the brain associated with impaired mental functions, scientists hope to eventually help children retrain their brains to follow alternative pathways and work around their cognitive weaknesses.

"The study strengthens our hypothesis that abnormalities in the brain's parietal lobe are a critical factor in the visual-spatial and numerical processing difficulties that we see in children with the chromosome 22q11.2 deletion syndrome,” said Simon.

In the study, the team compared 12 children with the syndrome to 15 healthy children. They found children with the chromosome deletion performed more poorly on experiments designed to test visual attention orienting, enumerating, and judging numerical magnitudes. All three tasks relate to how the children mentally represent objects and the spatial relationships among them.

Another study compared 18 children with the deletion to 18 healthy children. Using MRI techniques, the research team used newer methods to confirm previous findings of reductions in posterior brain volume and in grey and white matter. The researchers found changes in the shape, size and position of the corpus callosum, a structure that connects the brain's two hemispheres.

"It may be that the basic problem lies in how parts of the brain are connected,” said Simon. "It's like having a fuzzy signal on your cell phone - the phone is working, but the connections are defective.”

"Chromosome 22q11.2 deletion syndrome is one of a number of conditions with a similar pattern of visual-spatial and numerical impairments, grouped as nonverbal learning disabilities,” said Simon. "It may turn out that all these conditions have common changes to critical pathways in the brain.”

MEDICA.de; Source: Children's Hospital of Philadelphia