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Vanessa Troiani, Robert Schultz; Stimulus-driven visual attention engages subcortical visual areas in typical development but not autism. Journal of Vision 2013;13(9):849. doi: 10.1167/13.9.849.
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© ARVO (1962-2015); The Authors (2016-present)
Relevant stimuli efficiently engage attention, potentially due to engagement of the amygdala and enhanced processing in regions involved in visual salience. Based on the differential motivational-relevance of fearful faces, we hypothesized that a stimulus-driven motivational signal in the amygdala may increase connectivity with regions involved in processing visual salience. Furthermore, we examined whether a failure to engage this system contributes to impaired amygdala-guided attention in autism. To test this, we used a novel fMRI paradigm combining continuous flash suppression and an orthogonal letter-detection task to suppress fearful face and house stimuli from conscious awareness for the duration of an fMRI session. In a whole-brain analysis with 29 typically developing children, we find activation of the superior colliculus, thalamus, amygdala, and hippocampus in response to suppressed images (both faces and houses) compared to a no-stimulus control. Activations in these subcortical regions were not accompanied by changes in higher-level visual regions associated with processing faces and houses in conscious vision: We found no differentiation of the stimulus categories in the fusiform face area and parahippocampal place area using either mean responses or multi-voxel patterns, indicating that object-level information was successfully suppressed from higher-level visual cortices. In a connectivity analysis using regions of interest from our previous work, we find a category-specific (fearful faces > houses) increase in amygdala connectivity with the right pulvinar and left inferior parietal cortex, regions involved in processing visual salience. In conclusion, typical development is associated with activation of the amygdala in response to objects presented outside of conscious awareness and differentiation between objects based on an amygdala connectivity profile. We find no activation of the amygdala or other subcortical regions in response to suppressed stimuli in 32 children with autism, which indicates impaired stimulus-driven attention and a disturbance of adaptive processing of visual categories even prior to awareness.
Meeting abstract presented at VSS 2013
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