Current Studies

Nancy Lurie Marks Foundation

Diffusion Tensor Tracking of Connectivity Abnormalities in Autism
PI's: Nancy Minshew, MD; Thomas Conturo, PhD/MD; Susan Levy, MD

Autism is defined by symptoms in three domains: social interactions, language and communication, and restricted and repetitive behavior. Within each domain, there are many abilities that contribute to function. In the social area, theory of mind skills, face identity and face emotion recognition contribute to social dysfunction in autism. In the language area, verbal (left hemisphere) and nonverbal (right hemisphere) language contribute to the disability in communication. The cognitive basis of restricted and repetitive behavior in high functioning individuals with autism appears largely related to abnormalities in executive function and problem solving.

The neural basis of the cognitive and behavioral abnormalities is only beginning to be understood. Recent functional imaging studies (fMRI) in autism have revealed a reduction in functional connectivity across cortical brain regions involved in language, problem solving and social cognition; simple tasks showed normal connectivity. Structural brain studies have shown an increase in brain volume attributable largely to an increase in the outer white matter zone. This white matter connects immediately adjacent areas of cortex and makes longer distant connections between cortical regions within the same hemisphere. The corpus callosum, the major white matter pathway connecting the two hemispheres, is smaller in autism. Hence, connectivity has emerged as a key issue in the neurobiology of autism.

This study will investigate white matter connections using a new method called diffusion tensor fiber tracking to map white matter pathways related to each of the major symptom areas of autism. The size, shape, and density of these pathways in high functioning autistic teens and adults will be compared to matched normal controls and behavioral indices. This study will advance the understanding of connectivity in autism, pave the way for comparisons with functional connectivity, guide developmental neurobiologic studies, and provide an index for future cognitive rehabilitation strategies designed to enhance connectivity.