Altered auditory processing likely contributes to core social and attentional impairments in autism spectrum disorder (ASD). The auditory steady-state response (ASSR), a neural measure of auditory processing and cortical excitatory-inhibitory balance, has yielded mixed results in ASD. This study uses electroencephalography (EEG) to evaluate ASSR in ASD and unaffected siblings to clarify neural mechanisms underlying auditory deficits in autism. High-density 70-channel EEG was recorded in children (8-12 years, IQ > 80) with ASD (n = 53), typically developing (TD) peers (n = 35), and unaffected biological siblings (n = 26) during 500-ms binaural click trains (27- and 40-Hz) in an active oddball task. The ASSR was evaluated using data from frontocentral sensors, where the grand averaged response was greatest. No group differences were observed in frequency-following responses (FFR) to 27- or 40-Hz stimuli, although higher 40-Hz power and ITPC were associated with older age and better behavioral performance in ASD. The broad-band response from 180 to 250 ms was reduced in ASD for both stimulation frequencies-particularly in the low-frequency (< 8 Hz) range-and significantly correlated with IQ and age. Siblings showed intermediate broad-band responses. While FFRs appeared intact in ASD, we observed reduced broad-band response in the transition period to the steady state FFR, which was specific to low (< 8-Hz) frequencies. Intermediate responses in first-degree relatives suggest that this is related to genetic vulnerability for ASD and highlights its clinical relevance. These findings suggest intact sensory processing in ASD alongside possible top-down auditory feedback deficits, which may serve as a heritable neurophysiological marker.
Darrell et al. (Tue,) studied this question.