MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism

TLDR

Auditory and speech deficits in ASD motivate investigation of frequency‑dependent STG M50 and M100 neuromagnetic responses, with M100 latency delay indicating disrupted encoding of simple sensory information. To evaluate the frequency dependence of STG M50 and M100 neuromagnetic auditory evoked field responses in children with ASD versus typically developing controls. Whole‑cortex MEG was recorded from 17 typically developing children and 25 children with ASD while they listened to tones at 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 activity was examined. Children with ASD showed no M50 differences but had an 11‑ms delayed right‑hemisphere M100 latency, a delay that remained significant after adjusting for age, IQ, and language, and yielded 75 % sensitivity, 81 % specificity, and 86 % PPV at a 116‑ms threshold, suggesting a right‑hemisphere M100 latency delay is an electrophysiological endophenotype for autism.

Abstract

Abstract Motivated by auditory and speech deficits in autism spectrum disorders (ASD), the frequency dependence of superior temporal gyrus (STG) 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in children with ASD and typically developing controls were evaluated. Whole‐cortex magnetoencephalography (MEG) was obtained from 17 typically developing children and 25 children with ASD. Subjects were presented tones with frequencies of 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 STG activity was examined. No M50 latency or amplitude Group differences were observed. In the right hemisphere, a Group×Frequency ANOVA on M100 latency produced a main effect for Group ( P =0.01), with an average M100 latency delay of 11 msec in children with ASD. In addition, only in the control group was the expected association of earlier M100 latencies in older than younger children observed. Group latency differences remained significant when hierarchical regression analyses partialed out M100 variance associated with age, IQ, and language ability (all P ‐values <0.05). Examining the right‐hemisphere 500 Hz condition (where the largest latency differences were observed), a sensitivity of 75%, a specificity of 81%, and a positive predictive value (PPV) of 86% was obtained at a threshold of 116 msec. The M100 latency delay indicates disruption of encoding simple sensory information. Given similar findings in language impaired and nonlanguage impaired ASD subjects, a right‐hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism.