Fig. 4.

Cortical sources of visual crowding in TD and ASD groups. (A) Source estimates (z-scored values) of neural activity for each task condition (strong crowding, mid crowding and baseline) in the time-window corresponding to the N1 (250–350 ms) ERP. In the TD group, the pattern of activation recruits an increasing bilateral portion of the occipital, temporal and (superior) parietal cortex. Such modulation in the ASD group seems to be absent, especially when contrasting the mid and strong crowding levels. (B) Contrast maps between ASD and TD obtained after subtracting the neural response in the baseline condition. The cortical regions differently activated between the two groups spanned across the frontal and anterior-temporal portions of the left hemisphere, and the right occipital lobe (as listed in detail in Table 2: minimum size of 5 vertices, p < .05 uncorrected). In all these areas, the neural activation was significantly reduced in ASD as compared to the TD group.