Objects were presented that did differ in perceptual organization. It was investigated if ASD participants would show diminished top-down modulation.
The results show that at the behavioral level both participant groups were comparable at identifying shapes that were embedded in random oriented Gabor pieces. Accuracy and reaction time were not affected whether the shapes were shown by only contour, only texture, or both contour and texture. Furthermore, whether the objects were recognizable or not did also not differ between the two groups.
Brain activation patterns were not very different among the groups and detection of the shapes was found to be associated with involvement of brain regions from low-level to high-level regions at the ventral visual stream. Stimuli that were meaningful, that is, objects that were recognizable, were found to be associated with larger activation in the LOC as well as in the middle occipital gyri in the participants with ASD.
Top-down modulation and functional connections among areas of the ventral visual stream was present at higher cortical hierarchy but not the lower in ASD participants as compared to healthy control participants.
Accordingly, ASD participants might get less top-down signs from brain areas at the higher level as compared to healthy control participants. The result might be that there will be diminished facilitation as well as more difficulties for the identification of objects in ASD. Global processing was found to be normal in ASD (Sapey-Triomphe et al., 2020).
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