The proposed research will examine cortical sources of ERP components associated with face processing in infancy with a group of typically developing (TD) infants and a group of infants at high-risk for developing ASD (ASIBS). Deficits in face processing are a common impairment associated with ASD. Adults with ASD demonstrate patterns of neural response distinct from typical adults when viewing faces, as evidenced by longer N170 latencies to faces. However, relatively little is known about how early differences in brain development contribute to these differences in face processing. The proposed study will investigate potential differences between ASIBS and TD infants at a time when specialization for faces is developing, from 6 to 12 months. Two ERP components have been identified as pre-cursors to the face-sensitive adult N170, the infant N290 and P400. Evidence of face specialization can be detected from differences in the amplitude and latency of these face-sensitive components when viewing faces as opposed to objects. Additionally, these components are sensitive to inversion (which indicates specialized processing of faces) by 12 months of age in TD infants. No study has examined whether ASIBS show a face inversion effect at this age, but ERP studies with adults have shown that the N170 is not sensitive to face inversion in adults with ASD. The proposed research will identify the cortical generators of face-sensitive ERP components in infancy. Cortical source localization will be performed using head models based upon individual infants'MRIs. This method allows for more accurate classification of tissue within the head's interior, which is of particular significance when studying populations (such as infants) where there is a great deal of variability in head size and shape, even within a specific age group. Using realistic models to calculate current density within the head will allow for more accurate estimation of cortical sources of activation, which may allow for more fine-grained distinctions to be made between groups. Ultimately, this will allow us to identify brain regions active during face processing in TD infants and ASIBS, as well as document any differences emerging during this critical time period for face specialization.
The prevalence of autism spectrum disorders (ASD) is increasing annually, making it a public health concern. However, it is still unclear how differences in neural function in infancy lead to the widespread social impairments associated with these disorders. Recent research has found that by 10 months of age, infant siblings of children with ASD exhibit atypical neural processing of faces, but the present study would examine differences in the neural processing of faces during a critical time period (from 6 - 12 months) when specialization for faces is developing in typical infants.
