New York, Mar 08 00 (Reuters Health) -- Secrets of brain development and growth continue to emerge, thanks to the possibilities generated by new technologies. The latest advance comes from a joint US-Canadian group of researchers who used sophisticated imaging techniques to visualize changes in brain structure during childhood.

Led by Dr. Arthur W. Toga of the University of California, Los Angeles, School of Medicine, the team described their work as "the creation of spatially complex, four-dimensional quantitative maps of growth patterns in the developing human brain." Their report is published in the March 9th issue of the journal Nature.

Using magnetic resonance imaging (MRI), the researchers were able to perform a never-before-accomplished feat -- that of mapping, in detail, the changes occurring in children's brains over a period of years. Among the group's observations was the notable growth of the corpus callosum, a structure that serves to connect the two hemispheres of the brain and which contains hundreds of millions of nerve fibers.

According to Toga and his colleagues, a particular area of the callosum called the isthmus was found to be a "focus of extreme growth... (which) was detected consistently in all subjects tracked between 6 and 15 years (of age)."

This callosal area, associated with language and certain thinking skills, "grew more rapidly than surrounding regions across time spans before and during puberty (6-13 years), with growth attenuated shortly afterwards (11-15 years)," the team writes.

This growth pattern supports what is known about language acquisition, the researchers point out. "The ability to learn new languages declines rapidly over the age of 12 years, as does the ability to recover language function if linguistic areas in one brain hemisphere are surgically (removed)," Toga and colleagues explain.

Another possible application of this MRI technique is being suggested by the researchers, who "recently found that (a particular group of nerve fibers) crossing at the callosal isthmus, degenerates fastest in early Alzheimer's disease." They believe that their form of dynamic mapping "may... offer advantages in tracking fine-scale effects of therapeutic interventions in dementia (and other diseases)."

SOURCE: Nature 2000;404:190-193.