title: Larger extrastriate population receptive fields in autism spectrum disorders.
abstract: Previous behavioral research suggests enhanced local visual processing in individuals with autism spectrum disorders (ASDs). Here we used functional MRI and population receptive field (pRF) analysis to test whether the response selectivity of human visual cortex is atypical in individuals with high-functioning ASDs compared with neurotypical, demographically matched controls. For each voxel, we fitted a pRF model to fMRI signals measured while participants viewed flickering bar stimuli traversing the visual field. In most extrastriate regions, perifoveal pRFs were larger in the ASD group than in controls. We observed no differences in V1 or V3A. Differences in the hemodynamic response function, eye movements, or increased measurement noise could not account for these results; individuals with ASDs showed stronger, more reliable responses to visual stimulation. Interestingly, pRF sizes also correlated with individual differences in autistic traits but there were no correlations with behavioral measures of visual processing. Our findings thus suggest that visual cortex in ASDs is not characterized by sharper spatial selectivity. Instead, we speculate that visual cortical function in ASDs may be characterized by extrastriate cortical hyperexcitability or differential attentional deployment.
authors: Wellcome Trust Centre for Neuroimaging, Institute of Cognitive Neuroscience, Cognitive Perceptual and Brain Sciences, and Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom.
authors: D Samuel
authors: DS
authors: Schwarzkopf
authors: Elaine J
authors: EJ
authors: Anderson
authors: Benjamin
authors: B
authors: de Haas
authors: Sarah J
authors: SJ
authors: White
authors: Geraint
authors: G
authors: Rees
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002659:Child Development Disorders, Pervasive / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D014793:Visual Cortex / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult
keywords: autism; perceptual function; population receptive fields; retinotopy; tuning; vision