Electrophysiological Assessment of Visual Pathways in Children with Autism Spectrum Disorder and their Unaffected Siblings: In Search of an Endophenotype

Abstract

The current study utilized a battery of short-duration visual evoked potentials (VEPs) administered to children with autism spectrum disorder (ASD) (n = 23), unaffected siblings of children with ASD ( n = 17) , and typically developing children (n = 19). VEPs were administered to examine specific neural mechanisms and potential group differences. Steady-state VEPs were elicited from contrast-sweep conditions (bright- and dark-isolated checks) to examine the integrity of the visual pathways in each group. Amplitude, neural noise (amplitude error), and signal-to-noise ratio (SNR), were examined under each condition for each group. Clustered bar graphs indicate that although not all of the predicted group differences were found, the expected pattern was evident for the outcome measures, with the sibling group's responses falling at an intermediate level compared to the ASD and control groups. Multivariate analysis and multilevel linear modeling were used to examine group differences. For SNR, there were significant differences across groups for the dark-check condition (F(12, 100) = 2.005,p = .031, ,ηp2 = .194), but not the bright-check condition (F(12, 102) = 1.106,p = .364,ηp2 = .117). Children with ASD displayed significantly weaker SNRs than those of the typically developing group; however the unaffected sibling group did not differ significantly from either group. Group differences in amplitude were not significant. For neural noise, although there were not significant differences among groupsthe overall between-group differences in the final multilevel linear model trended towards significance (F(2, 58.782) = 2.508,p = .090) trended towards significance. These findings indicate that isolated-check VEP measures may be used as an endophenotype of ASD. Key words: autism spectrum disorder, visual evoked potential, endophenotype, unaffected siblings