Objectives: The aim of this investigation was to determine whether patterns of functional connectivity with the medial prefrontal cortex (mPFC) are related to verbal ability (verbal IQ and receptive language) across children with and without an ASD.
Methods: We conducted task-independent functional connectivity analysis on functional magnetic resonance imaging (fMRI) scans collected from sixteen typically-developing (TD) boys (12.3 ± 1.76; FSIQ: 119.0 ± 8.41) and 16 age- and IQ-matched high-functioning boys with ASD (12.4 ± 2.14; FISQ: 112.3 ± 13.6). Briefly, a nuisance model including prewhitening with task as an explanatory variable, white matter average timeseries, cerebrospinal fluid average timeseries and motion included as covariates was run and residuals computed. The average timeseries from the seed ROI (mPFC) was extracted from the residual image. Both the extracted timeseries and residual image were normalized and entered into subject-wise correlations to create mPFC functional connectivity maps for each subject. Whole-brain regressions on the functional connectivity maps using verbal IQ (VIQ) and receptive language scores from the Peabody Picture Vocabulary Test (PPVT-III) were conducted.
Results: A whole-brain regression on mPFC functional connectivity with verbal IQ scores revealed a positive correlation in posterior cingulate cortex (MNIx,y,z= -10, 41, 48; Z = 4.23), bilateral angular gyri (Right MNIx,y,z= 52, -54, 30; Z = 4.34; Left MNIx,y,z= -52, -56, 24; Z= 3.13), and right superior cerebellum (MNIx,y,z = 40, 076, -34; Z=4.52). An additional whole-brain regression on mPFC functional connectivity with receptive language scores from the PPVT demonstrated a positive correlation with right angular gyrus (MNIx,y,z = 46, -66, 40; Z = 3.81) and right superior cerebellum (MNIx,y,z = 44, -70, -34; Z = 4.18).
Conclusions: These results indicate that children with higher verbal IQ scores had increased anterior-posterior functional connectivity between medial prefrontal cortex and posterior heteromodal speech, language and attention areas. Similar to the positive correlation observed with VIQ, which taps expressive language ability, we found that children with better receptive language abilities, as measured by the PPVT, also demonstrate stronger long-range connectivity between the mPFC and parietal cortices. These findings support the contribution of long-range frontoparietal networks to verbal abilities and reflect the importance of these connections for language development and autism pathogenesis.