Several lines of research suggest that autism is a neurological phenomenon, but the precise associations between neurological activity and the key diagnostic symptoms of autism are yet to be completely clarified. This study examined EEG connectivity and Sensory Features (SF) in a sample of young autistic males by examining bi-directional neural connectivity between separate brain regions as the key potential correlate of SF. Forty male autistic participants aged between 6 and 17 years, with an IQ of at least 70, underwent EEG measurements of their Frontal, Occipital and Temporal region responses to low-, medium-, and high-intensity audiovisual stimulus conditions. EEG connectivity data were analysed via Granger Causality. SF was measured via parent responses about their sons on the Child Sensory Profile (2^nd ed.) (CSP-2). There were significant (p < .05) correlations between right hemisphere Frontal and Temporal connectivity and CSP-2 dominant scores, largely due to lower Temporal-to-Frontal than Frontal-to-Temporal connectivity. There were no significant correlations between general CSP-2 scores and EEG connectivity data collected during audiovisual stimuli. These results confirm and extend previous findings by adding bi-directional connectivity as an index of brain activity to other studies that used only uni-directional connectivity data when measuring SF. Although there may be a discrepancy between the kinds of information collected via instruments such as the CSP-2 and actual brain electrical connectivity across major regions, these results hold implications for the use of brain-training interventions with autistic boys.

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.

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.

Results indicated (i) minimal agreement between functional and effective connectivity for eyes-closed and eyes-opened conditions, (ii) significant (p < .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.

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.

Investigation of the neurological underpinnings of the diagnostic symptoms for Autism Spectrum Disorder (ASD) represents a potential pathway towards a biomarker for this disorder. One of the key symptoms of ASD is Sensory Features (SF), which refers to the difficulties that autistic people experience with particular kinds of environmental stimuli. Studies using eeg measures of neural connectivity across various regions of the brain hold promise in identifying how the autistic brain reacts to its environment. This commentary identifies several 'participant' and 'measurement' methodological issues that need to be adequately addressed in SF-eeg connectivity studies, and applies these comments to a sample of five previous studies. Recommendations are made for future research procedures.