Examination of stained post-mortem brain slices of children with autism suggest that the condition starts in the second and third trimesters of pregnancy during brain development.
The outermost layers of cells in the brain that give it its characteristic wrinkled appearance, is known as the cortex. The cortex is itself composed of six layers, which are each built out of different neuronal cell types such as pyramidal cells.
During normal in utero brain development, neurons develop and migrate throughout the cortex to their respective intended placements. In children with autism, however, dense patches of abnormally developed neurons were discovered in incorrect layers.
The five to seven millimeter patches that were located in the frontal and temporal cortices suggest a major failure in genetic expression during development.
The study, detailing evidence found in 22 donated brain samples, half of which were donated by children with autism, was published yesterday in The New England Journal of Medicine.
Researchers are hoping the results shed light some on the mysterious condition.
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