Neural Specialization for Faces and Letters in Autism

Background: Individuals with autism have been shown to exhibit behavioral and neural anomalies in face perception. These have been hypothesized to reflect a lack of expertise resulting from reduced social motivation and consequent inattention to faces during development. Previously presented data collected from a small sample of children with autism reflected preserved neural specialization for non-social information, i.e. letters of the alphabet.  The current study investigates perceptual expertise for social and non-social information in a large sample of children with autism and typical counterparts. 

Objectives: To compare electrophysiological indices of perceptual expertise for social and non-social visual information in individuals with autism. 

Methods: Event-related potentials (ERPs; 256 channel Geodesic Sensor Net) were recorded from high-functioning children with autism and typically-developing peers. Participants viewed social and non-social “expert” versus “non-expert” stimuli (human faces vs. houses, Roman letters versus pseudoletters). Peak amplitude and latency were extracted for a negative component at 170 milliseconds over lateral posterior scalp (N170). Behavioral assessments measured proficiency at letter and face recognition.

Results: Typical individuals displayed expertise effects for the N170 in response to both faces and letters.  In contrast, those with autism displayed expertise effects for letters only.  ERP parameters and behavioral measures of letter and face perception revealed correlations among processing speed and proficiency.  Analyses in progress will localize neural sources of activity using individual-specific 3D head models created with the Geodesic Photogrammetry System. 

Conclusions: Results add to the body of literature indicating social brain dysfunction in autism. Despite atypical brain response to faces, children with autism demonstrate intact neural specialization for non-social visual information, letters of the alphabet. Findings suggest preserved capacity for neural specialization when individuals with autism obtain sufficient exposure to and engagement with a visual stimulus class.