Attention Networks and Sociocommunicative Abilities in ASD: Functional Connectivity and Behavioral Performance
Attentional abnormalities, as documented in numerous studies of Autism Spectrum Disorders (ASD), are potential contributors to the emergence of socio-communicative deficits. According to Posner and colleagues (2004), attention is organized into three functionally separate but interrelated networks: alerting, orienting, and executive. Atypical attention function in ASD has been shown for specific attention networks using electroencephalography, functional magnetic resonance imaging, and functional connectivity MRI (fcMRI).
We used resting-state fcMRI and the modified Attention Network Test (mANT) to characterize the organization and efficiency of attention networks and their relationship to socio-communicative deficits in ASD. We predicted that in adolescents with ASD: functional-connectivity would be reduced within each attentional network, but atypically increased between networks (reflecting reduced independence of attention networks); attention modulation would be inefficient; and atypical connectivity and network modulation would be associated with socio-communication symptom severity.
The imaging study included 20 adolescents with ASD and 20 matched typically developing (TD) individuals. Imaging analyses explored seed-based connectivity within and between attention network regions, as well as between each network and the whole brain. The mANT was used in a subsample (n=14 ASD; 18 TD) to examine network efficiency and modulation. Main effects and interactions between conditions were assessed using the median response times of all correct trials entered into a 2(Group)x2(Alerting Tone)x2(Orienting Cue)x2(Congruency)x2(Stimulus-Onset-Asynchrony) mixed-model ANOVA. T-tests were conducted to test the interaction between network scores. Network and region specific fc-indices and mANT scores for individual networks were correlated with measures of socio-communicative functioning, including the Autism Diagnostic Observation Schedule (ADOS).
While no group difference was found for within and between network connectivity (ps>.05), significant differences were detected for whole-brain connectivity of each network, i.e., for connectivity with regions outside attentional networks (ps<.05). These differences were characterized by underconnectivity in the ASD group between the alerting network and cerebellum and somatosensory cortex, between the orienting network and parietal and somatosensory cortex, and between the executive network and superior parietal regions. Overconnectivity in the ASD group was detected between the alerting network and parietal regions, as well as the orienting network and frontal, superior parietal, temporal, and cerebellar regions.
MANT results showed a significant two-way interaction for orienting cue by group (F(2,50)=3.813, p=.029), and a significant three-way interaction for orienting cue by executive congruency by group (F(2,50)=3.280, p=.046). As a whole, the ASD group showed less efficient patterns of attention network function and interaction.
Correlations between network scores on the mANT and between network fc-indices showed reduced independence of attention networks in the ASD compared to TD group. There were significant correlations in ASD between alerting and orienting network scores and the ADOS Social and Total scores. Also, executive network fc-indices showed correlations with ADOS Communication scores. Greater ASD symptom severity is associated with reduced attention network efficiency.
Our findings support inefficient attentional function at the neural and behavioral levels in ASD. Atypical attentional function and organization were related to socio-communicative abilities suggesting a role in autism symptomatology.