Combining hospital MRIs with the mathematical tool known as network analysis, a group of researchers at UC San Francisco and UC Berkeley have mapped the three-dimensional global connections within the brains of seven adults who have genetic malformations that leave them without the corpus callosum, which connects the left and right sides of the brain.
These "structural connectome" maps, described in the upcoming April 15, 2013 issue of the journal Neuroimage, reveal new details about the condition known as agenesis of the corpus callosum, which is one of the top genetic causes of autism and was part of the mysterious brain physiology of Laurence Kim Peek, the remarkable savant portrayed by Dustin Hoffman in the 1987 movie "Rain Man."
While some people born with agenesis of the corpus callosum are of normal intelligence and do not have any obvious signs of neurologic disease, approximately 40 percent of people with the condition are at high risk for autism. Given this, the work is a step toward finding better ways to image the brains of people with the condition, said Pratik Mukherjee, MD, PhD, a professor of radiology and biomedical imaging at UCSF who was the co-senior author of the research.
Understanding how brain connectivity varies from person to person may help researchers identify imaging biomarkers for autism to help diagnose it and manage care for individuals. Currently autism is diagnosed and assessed based on cognitive tests, such as those involving stacking blocks and looking at pictures on flip cards.
While the new work falls short of a quantitative measure doctors could use instead of cognitive testing, it does offer a proof-of-principle that this novel technique may shed light on neurodevelopment disorders.
"Because you are looking at the whole brain at the network level, you can do new types of analysis to find what's abnormal," Mukherjee said.
The Connection between the Brain Hemispheres and Autism Agenesis of the corpus callosum can arise if individuals are born missing DNA from chromosome 16 and often leads to autism.
Scientists have long puzzled over what the link is between this disorder and the autistic brain, said co-senior author of the paper Elliott Sherr, MD, PhD, professor of neurology and genetics especially since not all people with this malformation develop autism.