"While autism is generally considered a developmental brain disorder, research has not identified a consistent or causative lesion," said Thomas Insel, director of National Institute for Mental Health, which funded the study.
"If this new report of disorganized architecture in the brains of some children with autism is replicated, we can presume this reflects a process occurring long before birth."
The same research team had previously found that the brains of children with autism were heavier than other children's, and that they had more neurons in the prefrontal cortex.
The brains sampled for this study "represented nearly the entirety of tissue suitable for study at the Brain and Tissue Bank for Developmental Disorders at the National Institute of Child Health and Human Development and the Harvard Brain Tissue Resource Center," said the article.
Still, the fact that only 11 were studied means that more research is necessary, said Andrew Adesman, chief of developmental and behavioral pediatrics at Steven & Alexandra Cohen Children's Medical Center of New York.
"This study would have been stronger if they had a larger sample and included a group of children who had neurologic deficits but not autism," said Adesman, who was not involved with the research.
He nevertheless described the team's techniques for identifying microscopic brain abnormalities as "extremely sophisticated."
While some of the physical brain changes in autism were already known to science, the latest research provides a more detailed look at how this happens.
"This study is particularly important as it points to the potential role of several genes involved in the specification of distinct cortical layers during early brain development," said Patrick Hof, vice-chair of the Fishberg Department of Neuroscience, Friedman Brain Institute, and Seaver Autism Center at the Icahn School of Medicine at Mount Sinai.
Research like this "can provide us with crucial clues to develop novel therapeutic strategies toward a cure," he said.