Despite the vast amount of behavioral data showing a pronounced tendency in individuals with autism spectrum disorder (ASD) to process fine visual details, much less is known about the neurophysiological characteristics of spatial vision in ASD. Here, we address this issue by assessing the contrast sensitivity response properties of the early visual-evoked potentials (VEPs) to sine-wave gratings of low, medium and high spatial frequencies in adults with ASD and in an age- and IQ-matched control group. Our results show that while VEP contrast responses to low and high spatial frequency gratings did not differ between ASD and controls, early VEPs to mid spatial frequency gratings exhibited similar response characteristics as those to high spatial frequency gratings in ASD. Our findings show evidence for an altered functional segregation of early visual channels, especially those responsible for processing mid- and high-frequency spatial scales.

In this paper, we address the question whether the early cortical visual processes of spatial channels tuned to low, mid, and high spatial frequency inputs in autism show some modified functional properties with respect to typical adults. VEPs recorded to sinusoidal contrast reversal gratings revealed similar response contrast functions for ASD and controls to low and high spatial frequency gratings. Moreover, contrary to the controls' results, VEP contrast sensitivity to mid spatial frequency gratings in ASD was not different from that obtained for high spatial frequency gratings. Our present findings provide evidence for an altered functional segregation of early visual channels, especially those responsible for processing mid-frequency spatial scale. It is thus possible that their tendency to process visual details stems from the fact that a wide range of visual stimuli that fall within the mid-frequency range may be processed using the same mechanisms as those devoted to process high spatial frequency information.