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Caroline Robertson, Dwight Kravitz, Freyberg Jan, Simon Baron-Cohen, Chris Baker; Atypical Lateral Interactions in Autism. Journal of Vision 2013;13(9):836. doi: 10.1167/13.9.836.
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© ARVO (1962-2015); The Authors (2016-present)
Atypical perception is regarded as a hallmark characteristic of Autism Spectrum Conditions (ASC), but its neural underpinnings are unknown. Building on our previous results deficits in coherent motion processing in ASC, we conducted two psychophysical studies probing the nature of lateral interactions in ASC. First, we investigated the sharpness of the spatial and temporal gradients of attention. In 42 adult participants (21 ASC) we varied the spatial (2.46-6.56°) and temporal (67-210 ms) offset of an exogenous cue relative to a subsequent target stimulus. In both groups, performance decreased with increasing target distance from the cue, reflecting the spatial gradient of attention (p<0.001). Critically, this gradient was steeper in individuals with ASC (p<0.009) and tended to evolve more rapidly in time. Further, the slope of the spatial gradient predicted autistic symptoms/traits in both ASC and control groups (p<0.017). This sharper gradient may reflect increased lateral interactions in early visual processing in ASC. Second, we investigated binocular rivalry, which reflects competitive interactions in visual cortex. In 39 adult participants (21 ASC) two images were presented on the horizontal meridian of a screen, each within a tinted square (red/green, width: 1.75°). A mirror stereoscope reflected the images into the participants' left/right eyes. Participants were instructed to continuously report their perceived image (red, green, or ambiguous). Individuals with ASC displayed a slower rate of binocular rivalry (p<0.016), longer ambiguous percepts (p<0.014), and a stronger tendency to revert to a previously perceived percept (p<0.022). Both rivalry rate and ambiguous percept durations strongly predicted autistic symptomatology (p<0.016). This reduction in binocular rivalry may reflect disrupted excitatory/inhibitory balance in ASC. Together, the sharper gradient of spatial attention and slower dynamics of binocular rivalry provide potential insight into the perturbations of neural circuitry that may underlie both perceptual and cognitive levels of autistic symptomatology.
Meeting abstract presented at VSS 2013
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