Abstract
BackgroundVisuospatial processing has been found to be mediated primarily by two cortical routes, one of which is unique to recognizing objects (occipital-temporal, ventral or “what” pathway) and the other to detecting the location of objects in space (parietal-occipital, dorsal or “where” pathway). Considering previous findings of relative advantage in people with autism in visuospatial processing, this functional MRI study examined the connectivity in the dorsal and ventral pathways in high-functioning children with autism.MethodsSeventeen high-functioning children and adolescents with autism spectrum disorders (ASD) and 19 age-and-IQ-matched typically developing (TD) participants took part in this study. A simple visual task involving object recognition and location detection was used. In the MRI scanner, participants were shown grey scale pictures of objects (e.g., toys, household items, etc.) and were asked to identify the objects presented or to specify the location of objects relative to a cross at the center of the screen.ResultsChildren with ASD, relative to TD children, displayed significantly greater activation in the left inferior parietal lobule (especially the angular gyrus) while detecting the location of objects. However, there were no group differences in brain activity during object recognition. There were also differences in functional connectivity, with the ASD participants showing decreased connectivity of the inferior temporal area with parietal and occipital areas during location detection.ConclusionsThe results of this study underscore previous findings of an increased reliance on visuospatial processing (increased parietal activation) for information processing in ASD individuals. In addition, such processing may be more local, focal, and detailed in ASD as evidenced from the weaker functional connectivity.Electronic supplementary materialThe online version of this article (doi:10.1186/1866-1955-6-37) contains supplementary material, which is available to authorized users.
Highlights
Visuospatial processing has been found to be mediated primarily by two cortical routes, one of which is unique to recognizing objects and the other to detecting the location of objects in space
For within-group effects, paired sample t-tests revealed a significant effect of condition in typically developing (TD) participants for reaction time (location detection: mean = 2590.16 ms; object recognition: mean = 3135.25 ms; t(17) = 6.51; p < 0.001), with more time needed for object recognition relative to location detection task
There was no significant effect of condition on accuracy of trials with responses in TD participants (location detection: mean = 70.8%; object recognition: 79.2%; t(17) = −1.39; p = 0.183)
Summary
Visuospatial processing has been found to be mediated primarily by two cortical routes, one of which is unique to recognizing objects (occipital-temporal, ventral or “what” pathway) and the other to detecting the location of objects in space (parietal-occipital, dorsal or “where” pathway). Investigations on the behavior of these networks in neurodevelopmental disorders, such as autism spectrum disorders (ASD) are sparse This is especially interesting considering the relatively intact or superior visuospatial processing abilities reported widely in autism [9,10,11,12]. FMRI studies have found greater activation within visuospatial areas and less activation in frontal areas in the ASD brain during such tasks [10,21] Evidence from these studies point to enhanced “lower level” (increased reliance on parietal/occipital areas) processing skills for objects in ASD individuals compared to typical control individuals. While this hypothesis has been frequently applied to face processing and feature detection within ASD, to our knowledge, there are no functional imaging studies specific to detecting objects and location in space in the ASD literature
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