Abstract
BackgroundWhile autism spectrum disorder (ASD) is characterized by both social communication deficits and restricted and repetitive patterns of behavior and interest, literature examining possible neural bases of the latter class of symptoms is limited. The fusiform face area (FFA) is a region in the ventral temporal cortex that not only shows preferential responsiveness to faces but also responds to non-face objects of visual expertise. Because restricted interests in ASD are accompanied by high levels of visual expertise, the objective of this study was to determine the extent to which this region responds to images related to restricted interests in individuals with ASD, compared to individuals without ASD who have a strong hobby or interest.MethodsChildren and adolescents with and without ASD with hobbies or interests that consumed a pre-determined minimum amount of time were identified, and the intensity, frequency, and degree of interference of these interests were quantified. Each participant underwent functional magnetic resonance imaging (fMRI) while viewing images related to their personal restricted interests (in the ASD group) or strong interest or hobby (in the comparison group). A generalized linear model was used to compare the intensity and spatial extent of fusiform gyrus response between groups, controlling for the appearance of faces in the stimuli.ResultsImages related to interests and expertise elicited response in FFA in both ASD and typically developing individuals, but this response was more robust in ASD.ConclusionsThese findings add neurobiological support to behavioral observations that restricted interests are associated with enhanced visual expertise in ASD, above and beyond what would be expected for simply a strong interest. Further, the results suggest that brain regions associated with social functioning may not be inherently less responsive in ASD, but rather may be recruited by different environmental stimuli. This study contributes to our understanding of the neural basis of restricted interests in ASD and may provide clues toward developing novel interventions.Electronic supplementary materialThe online version of this article (doi:10.1186/s11689-016-9149-6) contains supplementary material, which is available to authorized users.
Highlights
While autism spectrum disorder (ASD) is characterized by both social communication deficits and restricted and repetitive patterns of behavior and interest, literature examining possible neural bases of the latter class of symptoms is limited
Within-group contrasts In both groups, viewing images of one’s own interest elicited significantly higher BOLD signal relative to viewing images of other children’s interest in discrete clusters within the fusiform face area (FFA) masks. These findings held both within the broad AALdefined fusiform gyrus mask (Table 2, Fig. 2a, b) as well as within the more precise bilateral FFA1 and FFA2 masks (Table 3, Fig. 2c–f )
We have previously shown that both the amygdala and the orbital frontal cortex (OFC) are engaged by individuals with ASD when viewing images of their restricted interest, with the OFC being selective for images of one’s own interest versus novel pictures of others’ interest [4]
Summary
While autism spectrum disorder (ASD) is characterized by both social communication deficits and restricted and repetitive patterns of behavior and interest, literature examining possible neural bases of the latter class of symptoms is limited. Functional abnormalities have been identified in several brain structures, including the amygdala, superior temporal sulcus (STS), and a functionally-defined, face-selective area of the fusiform gyrus commonly referred to as the fusiform face area (FFA; [25, 26]) While these studies have explored the role of the social brain in ASD symptoms, the literature examining possible neural bases of increased levels of repetitive behaviors and circumscribed interests is far more limited. Klin and colleagues [29, 30] have suggested that individuals with autism find objects, rather than social stimuli, to be most salient This atypical attentional bias may lead to increased interaction with and preference for the non-social environment at the expense of social development. Topics of circumscribed interest elicit greater positive affect and arousal than do social stimuli in older individuals with ASD [48]
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