Scientists continue to study and learn about the autism spectrum disorder, and researchers at Boston Children’s Hospital are using a hot new method known as “network analysis” to look at connections in the brain. Autistic children have brain networks that favor lots of short-range connections, a new study has determined, possibly giving rise to autistic children’s ability to memorize simple facts, while sacrificing long-range connections to other regions in the brain.
It’s possible this difference explains in part why autistic children can have difficulty integrating information that requires several regions of the brain. An example might be determining when a facial expression is showing anger. This type of focus on what are usually unimportant details without integrating various pieces of information is typical of autism, and the evidence for why that happens may be in the networks of the brain’s neurons.
Press Release
A look at how the brain processes information finds a distinct pattern in children with autism spectrum disorders. Using electroencephalograms (EEGs) to track the brain’s electrical cross-talk, researchers from Boston Children’s Hospital have found a structural difference in brain connections. Compared with children who don’t have autism, those with autism have multiple redundant connections between neighboring brain areas at the expense of long-distance links.
The study, using a “network analysis” like that used to study airlines or electrical grids, may help in understanding some classic behaviors in autism. It was published February 27 in BioMed Central’s open access journal BMC Medicine, accompanied by a commentary.
“We examined brain networks as a whole in terms of their capacity to transfer and process information,” says Jurriaan Peters, MD, of the Department of Neurology at Boston Children’s Hospital, who is a lead author of the paper, as is PhD student Maxime Taquet of Boston Children’s Computational Radiology Laboratory. “What we found may well change the way we look at the brains of autistic children.”
Peters, Taquet and senior authors Simon Warfield, PhD, of the Computational Radiology Laboratory and Mustafa Sahin, MD, PhD, of Neurology, analyzed EEG recordings from two groups of autistic children: 16 children with classic autism, and 14 children whose autism is part of a genetic syndrome known as tuberous sclerosis complex (TSC). They compared these readings with EEGs from two control groups—46 healthy neurotypical children and 29 children with TSC but not autism.
In both groups with autism, there were more short-range connections within different brain region, but fewer connections linking far-flung areas.
A brain network that favors short-range over long-range connections seems to be consistent with autism’s classic cognitive profile—a child who excels at specific, focused tasks like memorizing streets, but who cannot integrate information across different brain areas into higher-order concepts.
“For example, a child with autism may not understand why a face looks really angry, because his visual brain centers and emotional brain centers have less cross-talk,” Peters says. “The brain cannot integrate these areas. It’s doing a lot with the information locally, but it’s not sending it out to the rest of the brain.”
Network analysis—a hot emerging branch of cognitive neuroscience—showed a quality called “resilience” in the children with autism—the ability to find multiple ways to get from point A to point B through redundant pathways.
“Much like you can still travel from Boston to Brussels even if London Heathrow is shut down, by going through New York’s JFK airport for example, information can continue to be transferred between two regions of the brain of children with autism,” says Taquet. “In such a network, no hub plays a specific role, and traffic may flow along many redundant routes.”
This quality of redundancy is consistent with cellular and molecular evidence for decreased “pruning” of brain connections in autism. While it may be good for an airline, it may indicate a brain that responds in the same way to many different kinds of situations and is less able to focus on the stimuli that are most important.
“It’s a simpler, less specialized network that’s more rigid, less able to respond to stimulation from the environment,” says Peters.