Researchers Use Stereo Investigator to Identify Abnormalities in Autistic Brains

A baby makes eye contact with a passing stranger and his social development begins. Unable to resist the infant’s smile, the stranger smiles back and the baby starts to learn about human emotion through facial expression. But some babies, especially those on the autism spectrum, don’t make eye contact. What compels these tiny humans to avoid the eyes of people around them? Scientists specializing in developmental disabilities say the flocculus, a brain region in the cerebellum integral to eye movement control, may play a role in atypical gaze.

In their study of the postmortem brains of 12 autistic subjects and 10 control subjects, the research team, led by Dr. Jerzy Wegiel of the New York State Institute for Basic Research in Developmental Disabilities, in Staten Island, saw abnormally large flocculi in eight autistic subjects. According to the study, published last month in Brain Research, seven of these subjects exhibited “poor, very poor, or no eye contact” during the course of their lives.

Using an MBF Bioscience system consisting of Stereo Investigator controlling a Zeiss Axiophot microscope and an automatic stage, the researchers performed a stereology study to assess regional and cell volume changes in the flocculi of both groups, using Cavalieri’s method of point counting and the Nucleator probe.

In different subregions of the cerebellum, namely the molecular and granule layers, they saw profound changes in volume and organization in autistic patients as compared to control subjects. For example, instead of forming a neat layer, granule cells formed loosely arranged islands. They also saw fewer Purkinje cells, defective axons, and weak dendritic arborizations in the autistic brains.

The abnormalities, they say, are the result of altered mechanisms controlling the healthy development of these regions, particularly “cortical folding, neuronal migration, spatial arrangement, and connectivity.” According to the paper, these abnormalities cause the oculomotor system to develop in unusual ways, resulting in eye movement control defects in autistic subjects, including poor eye contact.

Together these findings expand the understanding of developmental defects that may underlie oculomotor dysfunction in autistic subjects.

{Wegiel, J., Kuchna, I., Nowicki, K., Imaki, H., Wegiel, J., Yong Ma, S., … & Wisniewski, T. (2013). Contribution of olivo-floccular circuitry developmental defects to atypical gaze in autism. Brain research.}