Visual Evoked Potentials to Checkerboards in Adults with ASD

Background: In autism, higher level visual processing abnormalities have long been found; it is unclear what role lower-level “bottom up” visual processing plays in these deficits. In 8 adults with autism, Hadjikhani et al. (2004) found (via fMRI) that early stage visual processing areas were normally organized. Using visual evoked potentials (VEPs), early abnormalities in the visual processing stream have been found in a number of other neurological disorders (e.g., depression, schizophrenia, ADHD). As well, preliminary evidence from our lab suggests alterations in P1 amplitude and latency in children with ASD when viewing faces (Webb et al., 2007).
Objectives: The goal of this study was to examine the early time course of VEPs in individuals with autism to basic checkerboard stimuli.
Methods: In our study, 27 adults with high functioning autism spectrum disorder and 21 age and IQ matched controls were presented with a unilateral flashing checkerboard stimulus while high density VEPs were recorded. The N75, P100, N145 components were analyzed.
Results: Preliminary analyses suggest a high degree of similarity between control and ASD groups in early visual processing; both morphology and topography of the waveforms were similar. 
Conclusions: Lack of differences between groups would suggest that abnormalities in higher order visual processing in individuals with autism are not the result of earlier irregularities as assessed by ERPs.
Funding source: NIMH (U54MH066399)