Description
Autism spectrum disorder (ASD) is a set of developmental disorders characterized by impacted social and communicative abilities, restricted interests, and repetitive behaviors. Recent ASD research has shown that network-level communication within the brain may play a large role in the manifestation of these symptoms. Specifically, recent studies have suggested domain-specific patterns of increased connectivity for sensorimotor connections and decreased connectivity for supramodal or associative connections for both thalamocortical and cerebrocerebellar circuits in ASD. The current study aimed to test whether functional connectivity between cerebellar lobules and the neocortex was related to functional connectivity between thalamic nuclei and the neocortex. We further sought to determine how these deep brain functional connectivity patterns correlated with ASD symptom severity as measured by clinical assessments. Archival resting state fMRI data from 49 ASD and 49 typically developing (TD) participants (aged 7 to 17 years) were used for this study. ASD and TD participants were matched at the group level on age, nonverbal IQ, and in-scanner head motion. A standard fMRI preprocessing pipeline was utilized, including motion, slice-time, and field map correction, spatial smoothing and bandpass filtering, and removal of nuisance regressors (i.e., 6 rigid-body motion parameters, and signal from white matter and ventricles). Regions of interest (ROIs) for cerebral cortex, thalamic regions, and cerebellar lobules were obtained from the Jülich histological and Harvard-Oxford atlases. Total correlation analyses between the mean time series of each cortical ROI and deep brain parcel showed widespread overconnectivity in the ASD group compared to the TD group. This was the case for both thalamocortical and cerebrocerebellar iFC circuits, stemming from both sensorimotor and supramodal cortical seeds. These circuits also showed far less specificity in ASD, with generally higher correlations between the iFC pairings themselves. Finally, it was shown that for participants with ASD, as iFC patterns deviated from those of the TD group, symptom severity based on clinical assessments also worsened across several domains. These findings suggest that thalamocortical and cerebrocerebellar iFC may be guided by similar neural dynamics, which may have many implications for developmental hypotheses of ASD that focus on network formation.
