Abnormal functional connectivity of default mode sub-networks in autism spectrum disorder patients

Abstract

Autism spectrum disorders (ASDs) are characterized by deficits in social and communication processes. Recent data suggest that altered functional connectivity (FC), i.e. synchronous brain activity, might contribute to these deficits. Of specific interest is the FC integrity of the default mode network (DMN), a network active during passive resting states and cognitive processes related to social deficits seen in ASD, e.g. Theory of Mind. We investigated the role of altered FC of default mode sub-networks (DM-SNs) in 16 patients with high-functioning ASD compared to 16 matched healthy controls of short resting fMRI scans using independent component analysis (ICA). ICA is a multivariate data-driven approach that identifies temporally coherent networks, providing a natural measure of FC. Results show that compared to controls, patients showed decreased FC between the precuneus and medial prefrontal cortex/anterior cingulate cortex, DMN core areas, and other DM-SNs areas. FC magnitude in these regions inversely correlated with the severity of patients' social and communication deficits as measured by the Autism Diagnostic Observational Schedule and the Social Responsiveness Scale. Importantly, supplemental analyses suggest that these results were independent of treatment status. These results support the hypothesis that DM-SNs under-connectivity contributes to the core deficits seen in ASD. Moreover, these data provide further support for the use of data-driven analysis with resting-state data for illuminating neural systems that differ between groups. This approach seems especially well suited for populations where compliance with and performance of active tasks might be a challenge, as it requires minimal cooperation.

Functional connectivity-based subtypes of individuals with and without autism spectrum disorder

“…Assaf et al, 2010). Many studies have reported decreased FC between DMN regions in those with ASD (Assaf et al, 2010;Kennedy & Courchesne, 2008;Monk et al, 2009;Weng et al, 2010), although hyperconnectivity within this network has also been reported (Monk et al, 2009;Uddin et al, 2013a). One study found that hypo-or hyperconnectivity of the DMN may be region-specific (Doyle-Thomas et al, 2015).…”

“…The DMN has been a focus of many FC studies in those with ASD, particularly because it has been hypothesized that abnormal DMN functioning relates to decreased self-referential processing, a decreased ability to redirect attention from external to internal processing, and difficulties with theory of mind in ASD (e.g. Assaf et al, 2010). Many studies have reported decreased FC between DMN regions in those with ASD (Assaf et al, 2010;Kennedy & Courchesne, 2008;Monk et al, 2009;Weng et al, 2010), although hyperconnectivity within this network has also been reported (Monk et al, 2009;Uddin et al, 2013a).…”

Reduced Default Mode Connectivity in Adolescents With Conduct Disorder

“…For example, schizophrenia appears to be associated with reduced DMN connectivity in all subsystems of the network 27 , and this has been correlated with subsystem-specific deficits in cognitive processes 28 . Likewise, in MDD 64 , OCD, 65 and autistic spectrum disorders 66 , respectively, there is emerging evidence of disorder-specific abnormalities that may be tied to individual subcomponents of the DMN. To our knowledge, no empirical study has directly compared DMN connectivity across a range of clinical groups to test the specificity (or otherwise) of DMN disturbances.…”

Resting-state networks in adolescents with 22q11.2 deletion syndrome: Associations with prodromal symptoms and executive functions

“…No study to our knowledge has yet to examine the baseline neural processes that characterize the architecture of functional connectivity in youths with 22q11DS. Such studies may indeed be important, especially because recent investigations in other pediatric populations show that atypical functional connectivity contributes to the emergence of neurodevelopmental psychiatric disorders (Assaf et al, 2010;Fair et al, 2010).…”