Autism Spectrum Disorders (ASD) are characterized by social communication difficulties, restricted and repetitive behaviors (RRBs), and sensory atypicalities. The pathophysiology of autism remains poorly understood, and no diagnostic biomarker is currently available. High-resolution electroencephalography (HR-EEG) is a non-invasive method offering good spatial resolution (128 electrodes) and excellent temporal resolution (high sampling rate), enabling the recording of various brain wave types (delta, theta, alpha, beta, and gamma) associated with different states of consciousness and cognitive processes. One pathophysiological hypothesis regarding autism centers on the concept of an imbalance in neuronal excitation/inhibition (E/I). Existing literature describes beta and gamma oscillation power as indirect markers that may reflect this imbalance, thereby allowing EEG to be used in a clinical setting to investigate this hypothesis.

In this study, the authors adopted a dimensional approach to determine whether alterations in these rhythms correlated with the severity of autistic symptoms. A total of 127 subjects with ASD, aged 5 to 17 years, including a subgroup of 57 participants who had undergone a sensory assessment, underwent HR-EEG recordings whilst at rest with their eyes closed. Absolute power (total signal intensity without normalization) was extracted from the beta and gamma frequency bands for six regions of interest. Multiple linear regression models were used to examine the relationships between beta and gamma power and clinical dimensions of ASD, while controlling for the effects of age and sex. The results reveal a significant correlation between resting-state beta-wave power and the sensory hypersensitivity and hyposensitivity scores of the study subjects. An exploratory finding also suggests that increased gamma power in the right temporal region might be associated with the severity of restricted and repetitive behaviors.

These groundbreaking findings, the first obtained at a clinical level to demonstrate a significant link between beta power and atypical sensory processing, warrant further investigation, in particular through the study of other electrophysiological markers that can be used to establish indirect profiles of the E/I balance. Nevertheless, they open up new avenues for a better understanding of neurobiological processes and the early diagnosis of ASD.

 Contacts : Julie Chaudet (julie.chaudet@universite-paris-saclay.fr) ; Aline Lefebvre (aline.lefebvre@universite-paris-saclay.fr)