Feb. 13, 2002 ST. PAUL, MN – Withdrawing from social interaction and communication is a hallmark of autism. Now, researchers have identified structural differences in the brains of autism patients that might explain the behavor.
Using computerized imaging, researchers have observed minicolumnar abnormalities in the frontal and temporal lobes of autistic patients. The study by scientists at the Medical College of Georgia, the University of South Carolina, and the Downtown VA Medical Center in Augusta, Georgia, is reported in the current issue of Neurology, the scientific journal of the American Academy of Neurology.
Autism is a severe and pervasive developmental disturbance of childhood. The disorder is characterized by disturbances in social interactions and communication, as well as stereotyped patterns of interests, activities and behaviors.
A minicolumn is a basic organizational unit of brain cells and connective wiring allowing an individual to take in information, process it, and respond. Thus, any changes in size, shape or location of the minicolumn will have an effect on the processing capacity of the brain. For the study, scientists examined the brain tissue of nine autistic patients and nine controls using five measures: columnar width, peripheral neuropil space, mean interneuronal distance, compactness, and gray level index.
According to study author Manuel F. Casanova, MD, a neurologist and neuropathologist at the Downtown VA Medical Center in Augusta, Georgia, the examinations revealed that the cell minicolumns of autistic patients are significantly smaller, but there are many more of them.
Evolution of the brain has kept minicolumn size essentially constant while increasing total cortical surface area, which in larger brains has resulted in more columns per brain and thus more processing units and increased complexity, Casanova said.
This would be consistent with an existing theory that autistic individuals suffer a chronic state of overarousal, and portray abnormal behaviors to diminish the arousal. The lack of lateral inhibitors, contained in the cortex, would affect an individual's ability to discriminate between competing sensory information, said Casanova. Researchers do not yet know whether the difference in the number and size of the minicolumns is attributable to a gene mutation or some other factor.
The study was funded by grants from the Theodore and Vada Stanley Foundation and the VA Merit Review Board. Families donated the brain tissue used n the study.
The American Academy of Neurology, an association of 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its web site at http://www.aan.com.
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