- Diffusion MRI shows that autistic children have increased brain gray matter
The inability to relate to people and life situations in an ordinary way, a characteristic of autistic children, may be the result of an abnormally functioning mirror neuron system, according to a recent study led by Manzar Ashtari of Children’s Hospital of Philadelphia.
Results of the study were presented at the 93rd annual meeting of the Radiological Society of North America on Nov. 28. The researchers found that children with autism have increased gray matter in regions of the brain linked to the mirror neuron system, which facilitates learning by seeing as well as doing, by experiencing emotions or sensations, and by empathizing with and understanding the intentions of others.
A recent study indicates that children with autism have increased gray matter in regions of the brain associated with social processing, as highlighted on images acquired using diffusion tensor imaging.
The study showed that larger amounts of gray matter are associated with higher IQs in the normal brain but not in the autistic brain, indicating that the gray matter in the latter may not be functioning properly. The autistic children also had decreased gray matter in another region of the brain, which correlated with the severity of social impairment.
Thirteen male patients with high-functioning autism and Asperger’s syndrome and 12 control subjects, all with an average age of about 11 years, underwent diffusion tensor imaging, a technique that tracks the movement of water molecules in the brain and that traditionally is used to study the brain’s white matter.
However, the research team used the technique to assess gray matter by employing apparent diffusion coefficient-based morphometry, an indirect method that highlights brain regions with potential changes in gray matter volume. Unlike previous morphometric studies, the method is not dependent on tissue segmentation, so the risk of brain tissue misclassification is reduced.
The technique and findings of the study may aid in exploring and understanding brain abnormalities in autism, one of the fastest growing developmental disabilities in the US, as well as in related disorders.
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