Using Electroencephalography to Measure the Effects of Sensory Features upon Functional and Effective Connectivity in Children and Adolescents with Autism Spectrum Disorder

Abstract

<p>Autism Spectrum Disorder (ASD) is a neurodevelopmental condition, characterised by impairments in social communication and the presence of restricted and repetitive behaviours, activities, or interests. ‘Sensory Features’ (SF) are a key symptom of ASD, and affect 90-95% of individuals with ASD, manifesting as atypical behavioural, neurological, and self-regulatory responses to sensory stimuli in the environment. Although the overt behavioural characteristics of SF in people with ASD have been extensively investigated, internal neurophysiological processes of SF in the ASD population have been minimally explored. One method of identifying these internal neurophysiological processes associated with SF is by using electroencephalography (EEG) to measure the brain’s electrical activity, and the ways that regions of the brain communicate or ‘connect’ with each other. There is a paucity of research investigating the direct relationship between SF and brain neural connectivity in children and adolescents with ASD, and this issue was made the focus of this research. Therefore, the current study aimed to investigate the relationship between SF in the ASD population and neural connectivity via (i) analyses of five different types of EEG connectivity measurements based on resting EEG data during eyes-closed and eyes-opened conditions, and (ii) analysis of Granger Causality on naturalistic audiovisual low-, medium-, and high-intensity stimulus conditions. The current study also aimed to investigate whether there was a relationship between age and Granger Causality connectivity indices in the ASD sample.</p> <p>Forty-one male participants aged between 6 and 17 years, with an IQ of at least 70 and who were diagnosed with ASD took part in the current study. Connectivity analysis (using five methods: Coherence, Weighted Phase Lag Index-Debiased, Phase Locking Value, Granger Causality, and Phase Slope Index) and subsequent statistical analyses (using Pearson product moment and Spearman correlations, MANOVA, and paired samples t-tests) were conducted on EEG data from these participants.</p> <p>Results indicated (i) minimal agreement between functional and effective connectivity for eyes-closed and eyes-opened conditions, (ii) significant (<i>p</i> < .05) deficits in connectivity between right hemisphere frontal and temporal brain regions, and a lack of significant correlations between this connectivity and Sensory Quadrant data collected on the Child Sensory Profile ( 2^nded.) for audiovisual stimuli, (iii) no significant differences in connectivity between frontal and occipital regions for all resting and stimulus conditions, and (iv) no significant correlations between age and neural connectivity in frontal, temporal, and occipital regions in response to audiovisual stimuli. </p> <p>The results from this research add to the current literature and provide more evidence of atypical neuronal communication, especially between frontal and temporal regions, in regards to SF in male children and adolescents with ASD. Further research using a consistent connectivity method to analyse the associations between EEG connectivity and naturalistic experimental stimuli may provide more meaningful insights and suggestions for neurophysiological interventions to reduce the adverse effects of SF in individuals with ASD.</p>