Relationships between Auditory ERP Responses and Caregiver-Reported Sensory Behaviours in Young Children with Autism Spectrum Development

Background: Sensory processing differences in Autism Spectrum Development (ASD) are related to quality of life (Lin & Huang, 2017). These sensory processing differences are heterogeneous, and there have been calls to explore this heterogeneity multimodally (Uljarević et al., 2017). Previous multimodal investigations of sensory processing in ASD using both questionnaires and ERPs have generally included broad age ranges or used smaller sample sizes.

Objectives: The present study aims to explore relationships between auditory ERP responses and caregiver-reported sensory behaviours in a large sample. To allow exploration of loudness-dependency in ERP responses, stimuli were delivered at multiple loudness levels.

Methods: ERPs to auditory stimuli were investigated in 108 young participants with ASD (90 male, M_Age = 38.80mos, SD_Age = 6.17mos). While watching a quiet video, participants heard, via headphones, brief tones randomly varying in loudness of 50, 60, 70 or 80 dB SPL (200-300 trials/intensity) at an ISI randomly varying between 1-2s. 61-channel EEG was sampled at 1000 Hz. The global field power (GFP) was used as an index of neural response strength. Participants’ caregivers completed all seven Short Sensory Profile (SSP) subscales. Time-wise one-way ANCOVAs were conducted on ERP global field power with loudness as a factor and (separately) SSP total and subscale scores as covariates. Only effects with a p-value ≤ 0.01 sustained for ≥20ms are reported; main effects of loudness are not reported. Correlations between SSP scores and GFP in different loudness conditions were used to probe significant effects. Scores on items from subscales on which effects were found were then run as covariates.

Results: An interaction emerged between SSP total scores and loudness (105 – 133ms); less typical sensory behaviours were associated with higher GFP amplitudes in the 70 dB condition (r = -.28, p = .005). In a partially overlapping window, an interaction emerged between the SSP Auditory Filtering subscale and loudness (76 – 131ms); auditory filtering problems were associated with higher GFP amplitudes in the 80 dB (r = -.24, p = .01) condition. Interactions also emerged between loudness and scores on two items on the subscale, specifically those relating to distraction and trouble functioning (72 – 135ms) and difficulty working (81 – 130ms) amid background noise. Correlations yielded similar results to those observed on the complete subscale. Finally, an interaction emerged between Visual/Auditory Sensitivity and loudness (298 – 336ms); greater sensory sensitivity was associated with lower GFP amplitudes in the 80 dB condition (r = .29, p = .003). No other time-wise ANCOVA effects survived outlier removal.

Conclusions: The presence of loudness x SSP interactions emphasizes the importance of considering how sensory response patterns may be affected by the loudness of sensory stimuli. Early in processing (~75-135ms), difficulty with background noise appeared to be related to a stronger response to louder sounds, which could reflect difficulty inhibiting responses to these sounds. Surprisingly, later in processing (~300ms), visual/auditory sensory sensitivity was associated with a weaker neural response to louder sounds.