Disruption of large-scale brain networks is associated with autism spectrum disorders (ASD). Recently, we found that directed functional connectivity alterations of social brain networks are a core component of atypical brain development at early developmental stages in ASD (Sperdin et al., 2018). Here, we investigated the spatio-temporal dynamics of whole-brain neuronal networks at a subsecond scale in 90 toddlers and preschoolers (47 with ASD) using an EEG microstate approach. Results revealed the presence of five microstate classes that best described the entire dataset (labeled as microstate classes A-E). Microstate class C related to the Default Mode Network (DMN) occurred less in children with ASD. Analysis of brain-behavioural relationships within the ASD group suggested that a compensatory mechanism from microstate C was associated with less severe symptoms and better adaptive skills. These results demonstrate that the temporal properties of some specific EEG microstates are altered in ASD at early developmental stages.

Autism spectrum disorders (ASD) are associated with disruption of large-scale brain network. Recently, we found that directed functional connectivity alterations of social brain networks are a core component of atypical brain development at early developmental stages in ASD. Here, we investigated the spatio-temporal dynamics of whole-brain neuronal networks at a subsecond scale in 113 toddlers and preschoolers (66 with ASD) using an EEG microstate approach. We first determined the predominant microstates using established clustering methods. We identified five predominant microstate (labeled as microstate classes A–E) with significant differences in the temporal dynamics of microstate class B between the groups in terms of increased appearance and prolonged duration. Using Markov chains, we found differences in the dynamic syntax between several maps in toddlers and preschoolers with ASD compared to their TD peers. Finally, exploratory analysis of brain–behavioral relationships within the ASD group suggested that the temporal dynamics of some maps were related to conditions comorbid to ASD during early developmental stages.

Diminished orienting to social stimuli, and particularly to faces, is a core feature of autism spectrum disorders (ASDs). Impaired face processing has been linked to atypical attention processes that trigger a cascade of pathological development contributing to impaired social communication. The aim of the present study is to explore the processing of emotional and neutral faces using an eye-tracking paradigm (the emotional faces task) with a group of 24 children with ASD aged 6 and under and a group of 22 age-matched typically developing (TD) children. We also measure habituation to faces in both groups based on the presentation of repeated facial expressions. Specifically, the task consists of 32 pairs of faces, a neutral face and an emotional face from the same identity, shown side by side on the screen. We observe differential exploration of emotional faces in preschoolers with ASD compared with TD. Participants with ASD make fewer fixations to emotional faces than their TD peers, and the duration of their first fixation on emotional faces is equivalent to their first fixation on neutral faces. These results suggest that emotional faces may be less interesting for children with ASD. We also observe a habituation process to neutral faces in both children with ASD and TD, who looked less at neutral faces during the last quarter of the task compared with the first quarter. By contrast, TD children show increased interest in emotional faces throughout the task, looking slightly more at emotional faces during the last quarter of the task than during the first quarter. Children with ASD demonstrate neither habituation nor increased interest in the changing emotional expressions over the course of the task, looking at the stimuli for equivalent time throughout the task. A lack of increased interest in emotional faces may suggest a lack of sensitivity to changes in expression in young children with ASD.

Background Early preferential attention to biological motion is a fundamental mechanism priming the development of sophisticated skills to detect and react to social stimuli. Children diagnosed with autism spectrum disorders (ASD) demonstrate reduced visual orientation towards biological motion, however, the underlying neurobiological mechanisms are unknown. Methods We measured the neural oscillations in children with ASD (n=34, mean age 3.43 years) and age and gender matched typically developing children (TD, n=27) while watching videos of social biological (BM) and geometrical motion (GM). Their visual interest in BM stimuli was measured with eye-tracking techniques. Neural oscillations were measured as amplitude modulation of the frequency bands with the electroencephalogram and calculated as the power ratio between BM and GM conditions using scalp and brain source reconstruction analyses. Results We observed a reduced visual exploration of the BM stimuli along with (1) unchanged sensorimotor mu rhythm and (2) altered cortical alpha and beta power ratio in widespread right prefrontal areas associated with default mode and fronto-parietal networks in young children with ASD as compared to their TD peers. Furthermore, we measured significant correlations between prefrontal and posterior cingulate regions of the default mode network with the developmental quotient in both the ASD and TD groups. Conclusion We observed abnormal alpha and beta modulation of the fronto-parietal and default mode networks along with altered visual exploration of the social biological motion. These deficits represent core impairments of the disorder and may be informative in developing future behavioural and neuroregulation interventions, such as neurofeedback.