Objectives: We examined (1) functional connectivity among regions of the resting state network [i.e. precuneus (central hub) with anterior cingulate cortex, and middle temporal gyrus] and (2) functional connectivity between the precuneus and neighbouring regions [i.e. posterior cingulate cortex, calcarine, cuneal, lingual gyri and the primary visual cortex].
Methods: We report here on data from 65 participants between the ages of 9-15 years (ASD: n=31, and typically developing controls: n=34). A significant between-group difference was found in IQ (ASD: 93.14 ± 18.2 and TD: 116.61 ± 9.07, p<0.05). Functional Magnetic Resonance Imaging data were pre-processed using a combination of AFNI, FSL and locally developed software tools. Each participant’s functional scan was coregistered to their anatomical scan, and ROIs were drawn using the Harvard-Oxford cortical atlas. ROIs were iteratively eroded until the mean intravoxel cross-correlation within an ROI reached a threshold of 0.8 (based on the methods of Golestani and Goodyear, 2011). For each participant, we calculated the coefficient of determination (R^2, or the square of the correlation coefficient) among all regions, bilaterally. We tested for significant mean differences between control and ASD subjects using a two-tailed t-test.
Results: Significantly higher correlations were found between the precuneus and neighbouring regions in ASD compared to controls (all p< 0.05) and higher connectivity in the resting state network was observed in controls compared to individuals with ASD (all p<0.05).
Conclusions: These preliminary results suggest short range over-connectivity in children and adolescents with ASD, in the context of a under-connected resting state network. These findings extent our current knowledge of atypical functional connectivity in ASD into a younger population.
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