Atypical lateral connectivity: a neural basis for altered visuospatial processing in autism.

BACKGROUND: Autistic perception encompasses both inferior and superior performance on different types of visuospatial tasks. Influential neurocognitive models relevant to atypical perception (i.e., weak central coherence, enhanced perceptual functioning) can, to differing degrees, account for these findings. However, the neural underpinnings mediating atypical visuospatial autistic perception have yet to be elucidated.
METHODS: In the present study, we used a lateral masking paradigm to assess the functional integrity of lateral interactions mediating visuospatial information processing within early visual areas of autistic (n = 18) and nonautistic (n = 15) observers. Detection thresholds were measured for centrally presented Gabor targets flanked collinearly at different distances (experiment 1) and flanked orthogonally at different contrasts (experiment 2).
RESULTS: Autistic and nonautistic groups showed increased target sensitivity when the distance between collinear targets and flankers was small (3 lambda) but not large (6 lambda). However, the effect of small-distance facilitation was significantly greater for the autistic group. In addition, we observed a group-specific effect of contrast: in the autistic group, target sensitivity was enhanced by low flanker contrasts of both 5% and 10% luminance difference, whereas for the nonautistic group, this effect occurred at 10% contrast only.
CONCLUSIONS: These findings support the idea that atypical visuospatial perception in autism may originate from altered lateral connectivity within primary visual areas, differentially affecting perception at the earliest levels of feature extraction.