Scientists have spent years trying to decode the intricate maze that is the human brain. But one facet of this field of study we may not have been paying enough attention to is the way the tissues of the brain fold together to create the trademark ridges that visibly set this organ apart from the others. While some of us have assumed that these folds are the same for all people—or that we each have our own unique folding pattern that has nothing to do with our intellectual abilities—there may be a pattern lurking in these mysterious creases that could unlock new information about autism and other neurological differences between people.
In a recent study of school-aged children (7-19), half of whom had autism spectrum disorder and half of whom were neurotypical, children with ASD were found to have a larger amount of brain folding, also known as gyrification. This gyrification was particularly evident in the left parietal and temporal and right frontal and temporal regions of the brain, areas known for their connection to sound, spatial awareness, decision-making, and motor skills.
Early disruption of fetal development is believed to be responsible for the excess folds, because these specific areas of the brain are some of the first to develop during gestation. Some researchers also believe the increased folding in the brains of young children with autism may be an “overgrowth” of the brain that results in the sensory overload that causes many people with autism to retreat from loud noises and crowded places.
Children with ASD did appear to have slightly less folding on one part of the occipital lobe, where the brain processes vision. There were no differences in the brain volume or surface area between the two groups of children.
As the children aged, the folding of their brains slowly lessened, but the brain “unfolded” most quickly in the left precentral, right lateral occipital, and middle frontal areas of the brains of people with autism.
“It seems like [brain folding] is actually a rather sensitive anatomical metric,” says study leader Ralph-Axel Müller, professor of psychology at San Diego State University.
Interestingly, though, in a second study of 3-year-old boys (who were studied again at age 5—still younger than all the participants in the first study), a slightly different result was found. Boys with ASD showed less gyrification in certain areas of the brain than neurotypical boys did at age 3 (namely in an area associated with facial recognition), but their brain folding was otherwise very similar to that of neurotypical boys. (The only exception seemed to be those boys with ASD who had enlarged brains due to megalencephaly; these individuals had increased gyrification at both ages, and researchers believe they have a different subtype of autism.) As the boys aged, however, neurotypical brain gyrification stayed roughly the same while the gyrification of ASD brains increased.
Both teams hope more research will turn up more concrete results in the future, but for now, there seems to be an emerging pattern of slightly less gyrification in the brains of young children with ASD, followed by a period of rapid brain growth that leads to excess gyrification in autistic school-aged children. These physical differences balance themselves out over time, but autism, the behavioral marker of these neural changes, remains in most individuals long after the visible brain changes have vanished.
It would appear that the folding patterns of the human brain mean a lot more than we currently understand. While the latest research hasn’t unlocked any new treatments, there’s hope that it will help with earlier diagnosis of the disorder so that intervention can take place sooner.Whizzco