Many children with autism have an incredible ability to pick up on minute details within their environment, such as being able to identify dozens of brands of vacuum cleaners from their sound alone or to detect a single book out of place on a bookshelf.
This superior ability to observe details can often come at the expense of being able to integrate those details into a bigger picture. New research suggests that this tendency may be rooted in increased symmetry between the left and right sides of the brain.
In most people, the brain is highly asymmetrical and tasks like these are divided up between the two hemispheres. This specialization is a way for the brain to process different types of information more efficiently.
The two sides exhibit different processing styles. The brain’s left hemisphere is involved in things like analyzing the details of a situation, while the right hemisphere is responsible for integrating this information to create a coherent picture.
“[I]n a very loose and simplified analogy: The left sees the trees, the right sees the forest,” Dr. Ralph-Axel Mueller, the study’s lead author, told The Huffington Post.
In a study that sheds light on the way brain development gives rise to autism symptoms, neuropsychologists at San Diego State University found that the autistic brain is less likely to specialize between brain hemispheres. In other words, while most people rely more heavily on the right side of their brains, in the case of autism, the right hemisphere is less well-developed. Instead, the autistic brain is more symmetrical ― this means a person with autism is more likely to use both sides of the brain evenly, resulting in an impaired ability to put together information into an integrated picture.
Using MRI scans, scientists investigated how brain connections develop in children with Autism Spectrum Disorder, compared to children who develop in a typical fashion. The brain scans of the 44 typically developing children and adults who participated showed greater asymmetry and more densely developed connections in the brain’s right hemisphere. Integrative information processing probably requires more dense interconnectivity in the right side of the brain, Mueller explained.
Asymmetries were significantly reduced, however, in the test group of 41 young adults with autism.
“[Reduced asymmetry] can be interpreted as reduced specialization of the hemispheres, and more specifically reduced integrative abilities of the right hemisphere,” Mueller explained.
These findings align with the theory of weak central coherence, a behavioral hypothesis which suggests that people with autism are often good at perceiving small details but have a limited ability to see the bigger picture. Indeed, in the fourth edition of The Diagnostic and Statistical Manual, “persistent preoccupation with parts of objects” is listed as one of the diagnostic criteria for autism.
For people with autism, this can play out in a struggle to derive meaning from their environment and experiences. To go back to Mueller’s analogy, they see a whole lot of trees, but miss the forest. Reduced asymmetry may also contribute to other cognitive signatures of the disorder, including challenges with language and motor control.
Better understanding these kinds of brain differences can only help us to better understand not only the challenges of autism, but also how to help those with the disorder to develop their unique strengths.