The advantage in analyzing brain anatomy using CT and VBM is the complementary nature of the two methods, which in combination provide a direct measure of cortical grey matter, regions of the brain that consist primarily of nerve cell bodies. The combined method also provides a measure of subcortical grey matter as well as white matter, regions of the brain composed mainly of nerve cell fibres which have myelin sheaths, the protective covering that insulates and supports nerve cells. "The converging results found from CT and VBM analysis, allows us to make more confident interpretations about the structural brain differences found in autism," adds Dr. Hyde.
Regional differences in grey matter were found in socially-relevant and communication-related brain areas, as well as in areas implicated in repetitive behaviours and those found to play a role in empathic behavior. The study also identifies grey matter increases in autism in the visual cortex and for the first time, in the primary auditory cortex. "We believe that the visual and auditory cortical thickness increases may be related to enhanced visual and auditory perception in autism."
"These new results are extremely important because they offer a more accurate picture of the autistic brain, helping researchers improve early autism treatment strategies," says Dr. Anthony Phillips, Scientific Director of the Canadian Institutes of Health Research (CIHR) Institute of Neurosciences, Mental Health and Addiction. "Autism rates have been rising steadily in Canada, so CIHR is proud to support researchers who devote their time to look into this neurological condition."
The study's findings provide vital insight into autism by identifying structural differences in functionally relevant areas of the brain in a group of individuals with autism using a dual analytic approach for the first time.
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