Faculty Collaboration Database

Atypical lexicosemantic function of extrastriate cortex in autism spectrum disorder: evidence from functional and effective connectivity. Neuroimage 2012 Sep;62(3):1780-91

Date

06/16/2012

Pubmed ID

22699044

Pubmed Central ID

PMC3857700

DOI

10.1016/j.neuroimage.2012.06.008

Scopus ID

2-s2.0-84863513441 (requires institutional sign-in at Scopus site)   37 Citations

Abstract

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.

Author List

Shen MD, Shih P, Öttl B, Keehn B, Leyden KM, Gaffrey MS, Müller RA

Author

Michael S. Gaffrey PhD Associate Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adolescent
Adult
Brain
Brain Mapping
Child
Child Development Disorders, Pervasive
Humans
Image Interpretation, Computer-Assisted
Language
Magnetic Resonance Imaging
Male
Neural Pathways
Semantics