Brain Connectivity and Neuroimaging of Social Networks in Autism

Abstract

Impairments in social communication (SC) predominate among the core diagnostic features of autism spectrum disorders (ASDs). Neuroimaging has revealed numerous findings of atypical activity and connectivity of 'social brain' networks, yet no consensus view on crucial developmental causes of SC deficits has emerged. Aside from methodological challenges, the deeper problem concerns the clinical label of ASD. While genetic studies have not comprehensively explained the causes of nonsyndromic ASDs, they highlight that the clinical label encompasses many etiologically different disorders. The question of how potential causes and etiologies converge onto a comparatively narrow set of SC deficits remains. Only neuroimaging designs searching for subtypes within ASD cohorts (rather than conventional group level designs) can provide translationally informative answers.

Keywords: autism; heterogeneity; network connectivity; neuroimaging; social brain.

Figure 1.

Social Brain Networks. Core networks known to be involved in social cognition. Only main network regions, simplified as spheres, are shown with approximate location (excluding subcortical structures). Abbreviations: ACC, anterior cingulate cortex; Amy, amygdala; dMPFC, dorsomedial prefrontal cortex; FFA, fusiform face area; Ins, insula; IOG, inferior occipital gyrus; IPS, intraparietal sulcus; MNS, mirror neuron system; PCC, posterior cingulate cortex; PMC, premotor cortex; pSTS, posterior superior temporal sulcus; ToM, theory of mind; TPJ, temporoparietal junction; vMPFC, ventromedial prefrontal cortex.

Figure 2.

Convergence Scenarios. Cartoon of three convergence scenarios described in main text. Colored dots represent social network nodes diagrammatically. For anatomical locations see Figure 1. Abbreviation: SC, social communication.

Figure 3.

Two Distinct Pathways towards Translational Application of Neuroimaging in Autism Spectrum Disorders (ASDs). Left: Since brain features contain information about developmental history, imaging can contribute to the search for distal (epi)genetic causes by providing a catalog of brain phenotypes, each of which may be linked to a specific etiology with specific targets for precision medicine. Right: Neuroimaging can reveal a catalog of proximal causes of ASD symptoms that require intervention. Specific links between brain features and symptoms at the level of the individual can inform targets for precision intervention. While causal neuroimaging may contribute to precision medicine that may prevent the onset of the disorder, it is also possible that such intervention would reverse critical neurobiological conditions after onset and diagnosis. Conversely, intervention targets developed from symptomatic neuroimaging may be developed for earliest signs before the onset of full symptomatology. Therefore, the timing implications of the two imaging pathways are not absolute.