The Surprising Symmetry of Brains on the Autism Spectrum

MRI study finds brains of ASD subjects are more symmetrical than typical brains, which makes sense.


Though neurologists have debunked the old conventional wisdom that the human brain is cleanly divided into a right side for creativity and left for analytical thinking, it’s still the case that the two sides have their specialties. In most people the right hemisphere is denser with connections, but a new study of children and adolescents on the autism spectrum (ASD) suggests that the connections in their brains are more evenly distributed across the hemispheres than in others’.

(WALLYBIRD)

Language processing and speech are primarily handled in the left hemisphere of the brain, which also concerns itself with the processing of fine details. The right, on the other hand, works to integrate these details with other factors, including sensory input, and it’s also where auditory and visual sensory stimuli are processed. It’s assumed that the right hemisphere’s task of processing information from both hemispheres is the reason it has more connections than the left in the typical brain.

Neuropsychologists at San Diego State University’s Brain Development Imaging Lab used magnetic resonance imaging (MRI) diffusion tensor imaging to study the brains of 85 participants: 41 with ASD and 44 without. The were interested in seeing the density of brain connections throughout the brain’s white matter. The results were published in the Journal of the American Academy of Child & Adolescent Psychiatry December issue.

In typical developing brains, the scans did show that the right hemisphere had more densely-packed connections. “This fits with the idea that the right hemisphere has a more integrative function, bringing together many kinds of information,” the study notes.

The study’s MRI scans (RALPH-AXEL MÜLLER)

On the other hand, connections were more evenly distributed across the hemispheres of ASD brains. According to Ralph-Axel Müller, one of the study’s authors, “The idea behind asymmetry in the brain is that there is a division of labor between the two hemispheres. It appears this division of labor is reduced in people with autism spectrum disorder.” The study’s other authors are Ruth Carper and Jeffrey Treiber.

In people with ASD, it may be that the hemispheres are less specialized. While more study is needed, it seems like this fits with autistic people's enhanced skill with details and trouble with integrating these details into a larger picture, referred to as “weak central coherence” in the study.

One of the unresolved questions that will require further study is this: Is the symmetricality of ASD brains the cause of being on the spectrum or the result of autism?

Big Think Edge
  • The meaning of the word 'confidence' seems obvious. But it's not the same as self-esteem.
  • Confidence isn't just a feeling on your inside. It comes from taking action in the world.
  • Join Big Think Edge today and learn how to achieve more confidence when and where it really matters.
Sponsored by the Institute for Humane Studies
  • There are 2 different approaches to governing free speech on college campuses.
  • One is a morality/order approach. The other is a bottom-up approach.
  • Emily Chamlee-Wright says there are many benefits to having no one central authority on what is appropriate speech.

Active ingredient in Roundup found in 95% of studied beers and wines

The controversial herbicide is everywhere, apparently.

(MsMaria/Shutterstock)
Surprising Science
  • U.S. PIRG tested 20 beers and wines, including organics, and found Roundup's active ingredient in almost all of them.
  • A jury on August 2018 awarded a non-Hodgkin's lymphoma victim $289 million in Roundup damages.
  • Bayer/Monsanto says Roundup is totally safe. Others disagree.
Keep reading Show less
Big Think Edge
  • Economist Sylvia Ann Hewlett breaks down what qualities will inspire others to believe in you.
  • Here's how 300 leaders and 4,000 mid-level managers described someone with executive presence.
  • Get more deep insights like these to power your career forward. Join Big Think Edge.