Abstract
Most children with Autism Spectrum Disorder (ASD) have co-occurring language impairment, but its neural mechanisms are not well known. Excitation (E) / inhibition (I) imbalance is considered as a key neurobiological mechanism of ASD, and several electroencephalography (EEG)-based E/I balance metrics have been proposed in the previous studies. The goal of the present research was to focus on these metrics abstracted from the speech perception task to investigate their relation to language/communication in autistic youths. We used a high-density 128-channel EEG to register neural responses during speech perception task in the sex- and age-matched groups of youths with ASD (N = 162) and typically developing (TD) controls (N = 144), aged 7-18 years old. The results revealed alterations in the E/I measures in the ASD group, pointing to a higher level of excitation or neural 'noise' in the cortex as well as broadband reduction of spectral power during speech perception. A greater neural 'noise' reflected in the reduction of aperiodic exponent and offset was associated with lower verbal communication skills in youths with ASD. The findings suggested that the higher 'noisiness' in the cortical systems may be a relevant marker to monitor in relation to language/communication in ASD.