The Continuing Story of Connections in Autism: Truly A Distributed Neural Network Disorder

As a result of imaging technology, tremendous progress has been made in understanding the mind and brain in autism. The first major contribution was the evidence of increased total brain volume that led to the beginning acceptance of autism as a neural systems disorder. Over the course of a decade, functional magnetic resonance imaging (fMRI) studies generated evidence of functional underconnectivity across neural systems and of increased local connectivity in high functioning individuals with autism. In the last 3-5 years, diffusion tensor imaging studies have provided evidence of both micro- and macro-structural abnormalities in white matter pathways. Recently, fMRI studies have further characterized the cognitive and neural mechanisms underlying language and visual processing deficits in autism with clear implications for intervention. A converging theme across these studies is the lack of the innate specialization of circuitry in autism that is associated with neuronal organizational events. This section will review key findings that advance the definition of the neural basis of autism.