Examinations of social and non-social factors in the neurodevelopment of autism

Autism is a pervasive developmental disorder characterized by deficits in social and communication skills, as well as restricted interests and repetitive behaviors, with symptom onset by 3 years of age. Recent studies have documented structural and functional abnormalities in a variety of brain regions associated with social processing and perception in this population. As a result, there is a growing belief that autism can be explained by impairment in social brain systems, and several neurodevelopmental models have been proposed to explain the social and communicative impairments of individuals with autism. The current research explores the role social and non-social factors play in the neurodevelopmental basis of autism in three studies of functional brain development. Study 1 examines social and non-social semantic integration in young children with autism by analyzing event-related potentials recorded during the processing of word and environmental sound meaning within a picture context. Results suggest that the neural integration of word, but not environmental sound, meaning is impaired in these children, providing support for a social/non-social distinction in this area of functioning. Experiments 2 and 3 explore the early functional development of brain systems involved in face and object processing in the first year of life in autism by studying neurodevelopmental risk in infant siblings of children diagnosed with autism. Specifically, experiment 2 employs event-related potentials to examine the neural correlates of early stages of face and object processing in 10-month old infants, and experiment 3 employs visual psychophysical measures to assess the integrity of the magnocellular and parvocellular visual pathways in 6-month old infants. The results of experiment 2 suggest that familial risk for autism is associated with abnormalities in face and object processing in the first year of life. The results of experiment 3 suggest that familial risk for autism is also associated with abnormalities in the subcortical magnocellular visual pathway, which is believed to provide critical input for face processing in the first several months of life. Together, these results provide new insight into the roles social and non-social factors may play in the neurodevelopment bases of autis