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Cognition and behavior: Corpus callosum disrupted in autism

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Jessica Wright
27 November 2012

Two halves: Children with autism have a smaller corpus callosum, a structure that connects the left and right sides of the brain, than do controls.

Nearly half of children with malformation of the corpus callosum, which links the two hemispheres of the brain, have symptoms of autism, according to a study published 5 October in the Journal of Autism and Developmental Disorders1.

The malformed structure may limit connectivity through a brain region involved in language and social behavior, leading to autism symptoms, the researchers suggest.

The corpus callosum sits near the center of the brain and is made up of neuronal projections linking one hemisphere to the other. People lacking part or all of the corpus callosum — a rare birth defect called agenesis of the corpus callosum — may show mostly typical development, but have some social deficits, such as problems with self-awareness and emotion recognition.

In the new study, researchers analyzed performance on the Autism Spectrum Quotient (AQ), a diagnostic questionnaire, of 106 individuals with agenesis of the corpus callosum. Parents filled out the questionnaire for the 47 children and 20 teenagers in the study.

Based on cutoffs on the AQ, 45 percent of the children, 35 percent of the adolescents and 18 percent of the adults have autism, the study found.

The researchers also used magnetoencephalography, or MEG, to examine connections between brain regions as participants lay passively in the scanner. Defects in long-range connections have been found in individuals with autism, although discovery of the artifacts resulting from head motion has called some of these data into question.

Individuals who score as being less imaginative have weaker connectivity in the superior temporal gyrus than do those with more imagination. This brain region is involved in language and social behavior, and studies have shown abnormal connectivity in this region in individuals with autism.

Some children with autism have a small corpus callosum. This study suggests that children with autism should be screened for defects in this brain region, the researchers say.

References:

1: Lau Y.C. et al. J. Autism Dev. Disord. Epub ahead of print (2012) PubMed

Comments

Name: Mervyn Chappell
22 May 2014 - 9:30AM

Sorry for my ignorance, but is this piece of research showing that the inner development of the brain is either "the cause", or a contributing cause to the diagnosis/onset of autism??

Name: Elysa Marco
30 May 2014 - 10:09PM

This is a great question. The link between the corpus callosum and challenges with language and social skills has been long recognized. We are only now beginning to understand the link and individuals who are missing the corpus callosum are providing a special vantage for understanding the role of cross talk between the hemispheres. This article was the first to assess autism symptoms using an established screening tool, the AQ. There is a wonderful study just published that goes even further using more in-depth screening of lifetime symptoms and a current observed examination. So there does seem to be evidence that corpus callosum abnormalities contribute to challenges which constitute a clinical autism diagnosis.

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