Atypical lexicosemantic function of extrastriate cortex in autism spectrum disorder: evidence from functional and effective connectivity.
Journal Article (Journal Article)
Previous studies have suggested atypically enhanced activity of visual cortex during language processing in autism spectrum disorder (ASD). However, it remains unclear whether visual cortical participation reflects isolated processing within posterior regions or functional cooperation with distal brain regions, such as left inferior frontal gyrus (LIFG). We addressed this question using functional connectivity MRI (fcMRI) and structural equation modeling in 14 adolescents and adults with ASD and 14 matched typically developing (TD) participants. Data were analyzed to isolate low-frequency intrinsic fluctuations, by regressing out effects of a semantic decision task. For a right extrastriate seed derived from the strongest cluster of atypical activation in the ASD group, widespread effects of increased connectivity in prefrontal and medial frontal lobes bilaterally were observed for the ASD group, compared to the TD group. A second analysis for a seed in LIFG, derived from pooled activation effects in both groups, also yielded widespread effects of overconnectivity in the ASD group, especially in temporal lobes. Structural equation modeling showed that whereas right extrastriate cortex did not impact function of language regions (left and right IFG, left middle temporal gyrus) in the TD model, it was an integral part of a language circuit in the ASD group. These results suggest that atypical extrastriate activation during language processing in ASD reflects integrative (not isolated) processing. Furthermore, our findings are inconsistent with previous reports of functional underconnectivity in ASD, probably related to removal of task effects required to isolate intrinsic low-frequency fluctuations.
Full Text
Duke Authors
Cited Authors
- Shen, MD; Shih, P; Öttl, B; Keehn, B; Leyden, KM; Gaffrey, MS; Müller, R-A
Published Date
- September 2012
Published In
Volume / Issue
- 62 / 3
Start / End Page
- 1780 - 1791
PubMed ID
- 22699044
Pubmed Central ID
- PMC3857700
Electronic International Standard Serial Number (EISSN)
- 1095-9572
International Standard Serial Number (ISSN)
- 1053-8119
Digital Object Identifier (DOI)
- 10.1016/j.neuroimage.2012.06.008
Language
- eng