A group of investigators from San Diego State University's Brain Development Imaging Laboratory say they can see the effects of autism on the brain. They conclude that connectivity between the thalamus, a deep brain structure crucial for sensory and motor functions, and the cerebral cortex, the brain's outer layer, is impaired in children with autism spectrum disorders (ASD).

The thalamus is a crucial brain structure for many functions, such as vision, hearing, movement control and attention. They examined more than 50 children, with autism and without, according to their paper in BRAIN, and using  functional and anatomical magnetic resonance imaging (fMRI) techniques and diffusion tensor imaging (DTI) to examine connections between the cerebral cortex and the thalamus, determined that the pathways connecting the cerebral cortex and thalamus were found to be affected, indicating that these two parts of the brain do not communicate well with each other. 

"This impaired connectivity suggests that autism is not simply a disorder of social and communicative abilities, but also affects a broad range of sensory and motor systems," Dr. Ralph-Axel Müller, an SDSU professor of psychology who was senior investigator of the study. 

Disturbances in the development of both the structure and function of the thalamus may play a role in the emergence of social and communicative impairments, which are among the most prominent and distressing symptoms of autism.

They say the findings are consistent with growing evidence on sensory and motor abnormalities in autism. They suggest that the diagnostic criteria for autism, which emphasize social and communicative impairment, may fail to consider the broad spectrum of problems children with autism experience.

Aarti Nair, a student in the San Diego State University/University of California, San Diego Joint Doctoral Program in Clinical Psychology, reviews MRI scans of children with autism. Credit: SDSU Newscenter.